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Activity for Olin Lathrop‭

Type On... Excerpt Status Date
Edit Post #284637 Initial revision about 5 hours ago
Answer A: Low-frequency PWM-controlled Mosfet heater circuit
Your main complaint seems to be that the 24 V power rail sags 800 mV when the heater is on. Three responses pop to mind: So what? It probably isn't anyway. What did you expect? #1: So what? I don't see any harm in the 24 V supply actually being 23.2 V when the heater is on. Unless ...
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about 5 hours ago
Edit Post #284626 Post edited:
about 6 hours ago
Edit Post #284626 Post edited:
1 day ago
Edit Post #284626 Initial revision 1 day ago
Answer A: MOSFET not turning completely off
To protect against future changes and to provide something slightly more readable, here is your schematic: There is no immediately obvious reason the FET should blow, but there are a number of issues here: If "VIN17V" is to be believed, and the voltage really is 17 V, then that is way too m...
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1 day ago
Comment Post #284543 I don't think "outdated" should be used for "we would do this differently today", but rather "this won't work anymore today".
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8 days ago
Comment Post #284538 You can think of it that way. With the base voltage held constant, the transistor itself produces more emitter current when the emitter voltage drops.
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8 days ago
Edit Post #284545 Question closed 9 days ago
Comment Post #284545 Just like your other question, I'm closing this one too until you fix the sloppiness around some of the punctuation. Again, others have fixed this for you in the past, but you haven't learned from that. This seems to be the only way to get your attention. No fixes, no answers. If something isn't...
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9 days ago
Edit Post #284562 Question closed 9 days ago
Comment Post #284562 You've done this a bunch of times now, where you don't put a space after the period or question mark at the end of the sentence. Several times others have fixed it for you. We're not going to keep doing that. It's rude to continue throwing slop at us like that, especially after it has been pointed...
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9 days ago
Edit Post #284543 Initial revision 11 days ago
Answer A: React feature guidelines?
"Outdated" should be reserved for when an answer is wrong or misleading because something has changed since the answer was written, and it's not obvious that the answer applies to the older situation. Using this for editorial reasons, like marking anything with an 8 bit microcontroller as outdated w...
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11 days ago
Edit Post #284542 Initial revision 11 days ago
Answer A: React feature guidelines?
I think "dangerous" is pretty clear. It's when doing as recommended can cause significant damage to property or health. For example, recommending to a hobbyist to make a direct line-connected capacitor charge pump power supply for powering his breadboard would qualify. Dangerous does not mean ...
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11 days ago
Edit Post #284541 Post edited:
11 days ago
Edit Post #284541 Initial revision 11 days ago
Answer A: Most correct term for radio switching noise?
I don't think there is a formal term that means exactly what you describe. Switching transients generally means short term glitches that might cause noise, usually resulting from power being switched on or off. Note that this refers to the transients that cause the noise, not the noise itself. ...
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11 days ago
Edit Post #284538 Initial revision 11 days ago
Answer A: Find feedback of circuit
You are asking about feedback in this circuit, and how R3 fits into that: First, note that the circuit is an emitter follower, and has a voltage gain less than 1. Second, R3 bypasses the transistor for most input voltages. The block diagram you show is usually meant to be used when the for...
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11 days ago
Edit Post #284514 Question reopened 11 days ago
Comment Post #284514 Explain how you think how the circuit works. In particular, I want to know what you think R3 does, and why it has the value it does. Remember, we don't just answer homework questions here. We can help you thru the process or understanding a circuit, but that requires you to actively participate....
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12 days ago
Comment Post #284514 You ask about feedback and gain. These make no sense without an input and output. Gain can only be from one specific place to another specific place. Don't be so sloppy. Also, tell us how you tried to solve this problem and where exactly you are stuck.
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12 days ago
Edit Post #284514 Question closed 12 days ago
Edit Post #284395 Post edited:
20 days ago
Edit Post #284395 Post edited:
20 days ago
Edit Post #284395 Initial revision 20 days ago
Answer A: PTC resettable fuse leakage current
That's a marketing blurb. Look at the real datasheet. I just checked a polyfuse datasheet, and see that there is usually only about a 2.5 to 3.0 ratio of trip current to hold current. That should be enough to keep the motor from overheating. Polyfuses work on heat. When cold, they have low r...
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20 days ago
Edit Post #284344 Initial revision 24 days ago
Answer A: CAN "split" pin, bus termination and common mode stabilization
Can anyone explain the theory behind this pin You have already done so yourself: used to give a common mode stabilization and thereby reduce radiated emissions As far as I know, that is exactly the reason. Since the CANH/CANL lines are supposed to be a twisted pair, radiation comes from the...
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24 days ago
Edit Post #284304 Post edited:
26 days ago
Edit Post #284304 Initial revision 27 days ago
Answer A: Driving PMSM machine as an AC induction machine
A motor with stator winding and permanent magnets on the rotor, is very different from an AC induction motor. As a result, they require very different drive. You can just apply an AC signal to an induction motor, and there will be a net startup torque. The actual torque is a somewhat complicated...
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27 days ago
Comment Post #284282 This site has a wide audience, so you should define, or at the very least spell out PMSM and VFD. I know what they stand for, but if you spelled them out, particularly PMSM, you might notice yourself that PMSM and AC induction motor don't make sense together. Step back and explain in more detail ...
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27 days ago
Comment Post #284253 @Joel: "parallel plate inductor" doesn't make much sense.
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29 days ago
Comment Post #283936 While you are technically correct, I think you're also being pedantic in this case. Given that there is no such thing as an ideal current source in reality, it seems clear enough that the switch and current source together are meant to be an open when the switch is open, and producing a fixed curren...
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29 days ago
Comment Post #284253 I read this twice and still don't know what your setup is and what exactly you are asking. You start out talking about a parallel plate capacitor. OK so far. But in the next paragraph there is something about an inductor, but that was not previously defined or introduced. We can't know the assu...
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about 1 month ago
Edit Post #284253 Question closed about 1 month ago
Edit Post #284238 Initial revision about 1 month ago
Answer A: Change of pins in monostable multivibrator
The circuit you show doesn't make any sense: Start by examining the steady state condition. In steady state, C1 is effectively an open, so you ignore it. R4 keeps Q1 on. That means the collector of Q1 will be low, which keeps the base of Q2 low, which means Q2 is off. The diode doesn't d...
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about 1 month ago
Edit Post #284219 Question reopened about 1 month ago
Comment Post #284219 That's much better, and I wouldn't have closed it in its current state. However, since we're here, fix it the rest of the way. The junction dot to the right of C1 and below R4 is missing, V1 could be centered better, etc. Show me an example of neatness and attention to detail! Actually *try* to m...
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about 1 month ago
Edit Post #284225 Initial revision about 1 month ago
Answer A: Quality control of the site
There are four things we can do with bad or poorly written questions. In order of seriousness, these are: Leave a comment. Downvote. Close. Delete. The questions you mention have mostly been addressed with #1 and #2. Do you really think more severe measures are appropriate for th...
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about 1 month ago
Edit Post #284219 Question closed about 1 month ago
Comment Post #284219 That schematic is too much of a mess to look at. There are too many unnecessary zig-zags, gratuitous "loopy" corners, and rails that are not straight. Asking others to look at this mess is downright rude. It is like writing two paragraphs in text-speek. You've had plenty of warnings about slopp...
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about 1 month ago
Comment Post #284199 @Kran: Some questions *are* stupid. The OP isn't going to change without some reaction to that. In any case, if you think a question isn't answered well, write your own answer. We could use more good answers here, in addition to more questions. This site won't go anywhere if one person does most ...
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about 1 month ago
Comment Post #284199 @Kran: Yeah, these questions have been pretty lazy. I haven't been upvoting the lazy ones, and sometimes downvoting. We want to help students, but we also aren't here to read the datasheet to people. At this point in the life of this site, I'm being more tolerant and using these questions as a way...
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about 1 month ago
Comment Post #284207 There were two flags to close this question. I'm not going to close it, but don't be so lazy. This is almost certainly why you are getting downvotes. Look at a few datasheets yourself. If you don't understand what the datasheets are saying, then ask about that.
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about 1 month ago
Edit Post #284199 Post edited:
about 1 month ago
Edit Post #284199 Initial revision about 1 month ago
Answer A: Capacitance of inductor
What is a typical value for capacitance of a real inductor? "Typical" capacitance is a useless to design circuits with. It will also vary considerably by inductor size, geometry, and materials used. The only real answer is in the datasheet of whatever inductor you are considering using. There...
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about 1 month ago
Comment Post #284076 @Carl: Self-answered questions are allowed here. Of course a self-answered question should be the kind that someone else might reasonably run into, and both the question and answer must be well written, well presented, and correct.
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about 1 month ago
Comment Post #284074 Asking for the voltage of a "circuit" is meaningless. It's obviously 0 around any closed loop. It would make sense to ask about the voltage between two specific points, or across a specific component.
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about 1 month ago
Edit Post #284046 Post edited:
about 1 month ago
Edit Post #284046 Post edited:
about 1 month ago
Edit Post #284046 Initial revision about 1 month ago
Answer A: Inductance vs frequency
No. An inductance is an inductance. One way to look at an inductance is as an impedance that is a function of frequency:     Zind = ωL = 2πfL Where Zind is the impedance magnitude of an inductance, ω and f the applied frequencies, and L the inductance. When &omega...
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about 1 month ago
Comment Post #283958 OK, but don't tell me here, <i>fix the question</i>.
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about 1 month ago
Comment Post #283958 How coupling effects the series inductance is a good question, +1. However, it's ambiguous to talk about the inductance "of this circuit". Do you really mean the two inductors in series? Do you mean the inductors and resistor as view from the voltage source?
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about 2 months ago
Comment Post #283956 No, 2(4/9) <b>is</b> dimensionless. That's what you wrote.
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about 2 months ago
Comment Post #283956 Seriously!? Just read the whole post looking for errors. Obviously you haven't done this yet.
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about 2 months ago
Comment Post #283956 Whether one can guess the units is not the point. It's still <b>just plain wrong</b> to equate a value of Volts to a dimensionless quantity.
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about 2 months ago
Comment Post #283956 I've said this before, so this time you get a -1 right away. We do engineering here, where units are important. Every numeric value that is not dimensionless <i>must</i> be shown with its unit. Units must match on opposite sides of every equals sign. If not, the equation is wrong, just like if th...
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about 2 months ago
Comment Post #283955 Much better schematic, +1.
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about 2 months ago
Comment Post #283956 There several errors because it seems you copied and pasted this answer from your answer to a similar question about an inductor. You should carefully read over the whole post before posting, then sometimes again a while after posting. That will catch a lot of this sloppiness.
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about 2 months ago
Edit Post #283936 Post edited:
about 2 months ago
Edit Post #283936 Post edited:
about 2 months ago
Comment Post #283936 Why would I want to do that? As far as I can tell, it answers the question correctly. What do you think is wrong?
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about 2 months ago
Edit Post #283909 Post edited:
about 2 months ago
Edit Post #283936 Initial revision about 2 months ago
Answer A: Current and voltage of inductor
For reference, here is your circuit properly drawn with component designators: The question is what happens when the inductor current starts at 0, then the switch is closed. The first observation should be that the current source and the two resistors can be reduced to the equivalent Norton...
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about 2 months ago
Comment Post #283926 I told you before, always include component designators on your schematic. -1 for ignoring this requirement. Ping me when you fix it, and I'll undo the downvote.
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about 2 months ago
Comment Post #283906 Oops. Yes, I meant to say "minimum".
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about 2 months ago
Edit Post #283909 Initial revision about 2 months ago
Answer A: Select resistor for a diode
What the "appropriate" value of R1 is depends on what you are trying to achieve, which you haven't told us. Will this device be used in bright light, like outdoors, and the LED therefore needs to be as bright as possible? Is it an illumination source? Is it just an indicator, and it only needs to ...
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about 2 months ago
Comment Post #283904 The equation you use that implies the LED current as a function of the voltage across it is stated nowhere in the datasheet. You should only go by what it says in the datasheet. Also 5 digits is absurd in this case, especially due to the high temperature dependence of LEDs in general. "295.05 &Ome...
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about 2 months ago
Comment Post #283906 The general form of this answer is correct, +1. However, you shouldn't be using the typical forward voltage drop, but the worst case (highest) for the current you want. The resulting calculation that you show than results in the <i>minimum</i> resistance to not exceed the maximum current rating of ...
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about 2 months ago
Edit Post #283901 Initial revision about 2 months ago
Answer A: Diode like a frequency mixer
A diode mixer exploits the fact that the voltage across a diode is the log of the current thru it, to a good enough approximation for many uses. Now note that multiplication can be performed by taking the log of two values, adding the logs, then doing the un-log (take the exponential) of the result....
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about 2 months ago
Edit Post #283693 Initial revision about 2 months ago
Answer A: Thermal relief for through-hole on multi-layer PCB
That's a rather strange thermal relief pattern. It's also not clear where the hole is supposed to be. A proper thermal pattern has a plated hole and annular ring around the hole as usual. Then there is a gap with only a few narrow bridges connecting the annular ring with the surrounding plane. ...
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about 2 months ago
Edit Post #283663 Post edited:
about 2 months ago
Edit Post #283663 Initial revision about 2 months ago
Answer A: What is the difference between emitter and collector of a transistor?
I see you already have an answer based on the device physics. I'll answer that this means in a circuit. BJT (bipolar junction transistors) do work in reverse, at least somewhat. Generally, the characteristics aren't as good, particularly the gain. However, in most cases you still get some gain ...
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about 2 months ago
Edit Post #283659 Initial revision about 2 months ago
Answer A: SPI modes difference
"Stream" and "memory mapped" should be defined in the documentation for whatever microcontroller you are using. "Memory mapped" can mean different things. It might be just a different way of saying DMA, meaning the peripheral gets and puts data directly to memory buffers without code intervention...
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about 2 months ago
Edit Post #283587 Post edited:
2 months ago
Edit Post #283587 Initial revision 2 months ago
Answer A: $Q$ and $\overline{Q}$ in bistable multivibrator
Whichever you choose. I notice that you deliberately made the gain of one transistor a little higher than the other. That is irrelevant. The positive and negative outputs don't depend on the power-up state. They depend on which way the outputs go in response to inputs, like SET and CLEAR. Yo...
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2 months ago
Edit Post #283453 Initial revision 2 months ago
Answer A: A signal with one mode or with three or more modes
with just one mode Others have already explained that "discrete" means a finite set of values, not just two. This is to point out that having just one "mode" (it seems you mean symbol) doesn't make any sense. A signal that can only ever be in one value is no signal at all since it can't carry ...
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2 months ago
Comment Post #283361 I don't know. I thought it was a reasonable question and upvoted it. It is unfortunate that users can downvote something anonymously and without explanation.
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2 months ago
Edit Post #283365 Initial revision 2 months ago
Answer A: Motor Controller - What might be the purpose of these resistors?
Reasons this is sometimes done: To get higher power dissipation. To get higher voltage capability. To get lower parasitic capacitance. For 1 and 2 the "normal" answer is to use a resistor rated for the required power or voltage in the first place. However, there are some advantages t...
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2 months ago
Edit Post #283331 Post edited:
2 months ago
Edit Post #283331 Post edited:
2 months ago
Edit Post #283331 Initial revision 2 months ago
Answer A: Adding resistance to varactor circuit
in my schematic we must add R1 correct? No. Ultimately you are adjusting the varactor with a DC voltage that has a certain impedance. You can think of it as a Thevenin source. In your case, the DC voltage is created by the divider of Rs and Rv, then the impedance increased by R1. However, yo...
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2 months ago
Edit Post #283242 Initial revision 2 months ago
Answer A: Is English translation of technical terms on-topic?
I think such questions are OK as long as they are EE-specific. General purpose dictionaries often do a poor job with specialized technical terms, especially when they are the same or similar as regular words in either language. There can also be nuances how EE-specific terms are used in different c...
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2 months ago
Edit Post #283213 Post edited:
2 months ago
Edit Post #283213 Initial revision 2 months ago
Answer A: Division of binary numbers logic circuit
I dont understand how to make a logic circuit which does that job:check if the divisors is greater and equal or less than the most left digits of the divident So think about it. Break it down into small chunks. Let's ignore the reason behind your question and try to make a digital block that com...
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2 months ago
Edit Post #283172 Post edited:
2 months ago
Edit Post #283172 Post edited:
2 months ago
Edit Post #283172 Post edited:
2 months ago
Edit Post #283172 Initial revision 2 months ago
Answer A: 2 bit subtractor using full subtractor
We don't just give direct answers to homework (or homework-like) questions here, but can help you work thru the problem on your own. You might consider trying to synthesize a subtractor from scratch, just like you would an adder. The fundamental building block of an adder is the half-adder. It t...
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2 months ago
Edit Post #283099 Initial revision 3 months ago
Question What is this metal panel under power lines?
I was hiking around the Berkshires in western Massachusetts yesterday, and came across this metal panel where some power lines were crossing a ridge: Image alt text Image alt text Image alt text The panel is a few meters wide, and appears to have no electrical connection to it. It cost...
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3 months ago
Comment Post #282848 Please don't include the disclaimers that you show. It's your personal content, so you can use it here too without it being plagiarism. As for stating that the answer is made up, that just adds noise. Someone with that problem looking for the answer isn't going to care. Everyone can see that the ...
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3 months ago
Edit Post #282850 Post edited:
3 months ago
Edit Post #282850 Initial revision 3 months ago
Answer A: Can a paper be a tutorial or textbook-like?
This is a good question. I wasn't originally envisioning introductions to known concepts, but that might work if well written. If so, the Paper should at least be clearly labeled as such. We don't have a lot of Papers, and I wouldn't want to see introductory material drowning out new concepts. I ...
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3 months ago
Edit Post #282849 Post edited:
3 months ago
Edit Post #282849 Initial revision 3 months ago
Answer A: What are the guidelines for porting one's answers from ElectricalEngineering.SE, if any?
Sorry I didn't notice this earlier. We definitely don't just want to import questions and answers directly from SE. This has been discussed several times on various Codidact sites. Some of the first few Codidact sites did mass-import from SE, and that didn't go very well. Those sites are doing ...
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3 months ago
Edit Post #282575 Post edited:
3 months ago
Edit Post #282746 Post edited:
3 months ago
Edit Post #282746 Post undeleted 3 months ago
Edit Post #282746 Post deleted 3 months ago
Edit Post #282746 Question closed 3 months ago
Edit Post #282742 Post edited:
3 months ago
Edit Post #282745 Initial revision 3 months ago
Answer A: Input offset voltage/bias current noise contribution in operational amplifiers
While input offset voltage is technically noise in the sense that it is something unwanted added to the signal, it is not included in opamp noise specs as far as I have seen. Think of the "noise" spec as the AC part of the noise, with the offset voltage and current telling you about the DC part of...
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3 months ago
Edit Post #282738 Post edited:
3 months ago
Edit Post #282738 Post edited:
3 months ago
Edit Post #282742 Post edited:
3 months ago
Edit Post #282738 Post edited:
3 months ago
Edit Post #282738 Post edited:
Fixed image.
3 months ago
Edit Post #282742 Initial revision 3 months ago
Answer A: Electric circuit with antenna
Antennas are not lumped-parameter systems. They may be open circuits or shorts at DC, but this changes as the frequency goes up. They aren't just a bunch of wires anymore at the intended operating frequency. Take a simple dipole as example. It's just two disconnected wires at DC, but that doesn...
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3 months ago
Edit Post #282729 Question closed 3 months ago
Edit Post #282724 Initial revision 3 months ago
Answer A: Diodes used in mixers
Take a look at the circuit and try to see what function it will perform on the input signals to yield the output signal. For simplicity, let's consider the diode ideal, R1 and R2 the same, and R3 much larger. R1 and R2 will average the two input signals onto the anode of the diode. The diode wil...
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3 months ago
Edit Post #282711 Question reopened 3 months ago
Edit Post #282721 Initial revision 3 months ago
Answer A: Trouble understanding how to use adjustable LDO regulator
I just happened to re-read this question, and I now think I see better what Microchip was trying to say here: On closer examination, I think this is actually correct but badly worded. I believe it should be interpreted as: Dropout voltage is defined as the input-to-output differential when...
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3 months ago
Comment Post #282672 @Kranulis: While we do give some extra slack, ultimately we don't tolerate lazy students or sloppy engineering just because this site is still young. If this site had high traffic, this question (and probably a few others with the same crayon schematics) would have simply been closed and forgotten. ...
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3 months ago
Edit Post #282711 Question closed 3 months ago
Comment Post #282711 This question is too broad in its current form. Show a circuit of what you call a "unbalanced frequency mixer", and we can probably explain how it works. Or, give a proper spec for what this circuit is supposed to do, and we might be able to show how diodes could be used to advantage.
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3 months ago
Edit Post #282696 Initial revision 3 months ago
Answer A: MOSFET differential to single ended converter intuition
To be clear and protect against possible future edits, here is the circuit being discussed: As you say, this is a differential to single ended converter. In this case, the MOSFETs have likely been optimized so that they act as voltage-controlled current sources over most of their range. They...
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3 months ago
Edit Post #282672 Post edited:
3 months ago
Edit Post #282672 Initial revision 3 months ago
Answer A: Voltage of tank circuit is invalid
You need to be more careful. First, you should have been able to see for yourself that the first equation isn't written right. I'll assume the whole "-0.5t" is the exponent of e. You were too sloppy to notice, or too lazy to fix it. Either way, it's really rude to the volunteers here. That's w...
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3 months ago
Edit Post #282627 Post edited:
3 months ago
Edit Post #282627 Initial revision 3 months ago
Answer A: Capacitor in 2nd stage of opamp
That looks like the internal compenstation capacitor. It creates a single dominant pole over most of the opamp's intended operating range. Opamps with dominant pole compensation can be characterized by a fixed gain bandwidth product from a bit past the dominant pole frequency and higher. This ch...
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3 months ago
Edit Post #282585 Question reopened 3 months ago
Comment Post #282585 Hmm. It's still pretty hard to read. What's that thing in the top middle of the schematic, for example? Also, the equations in your text are unreadable. We have MathJax here for that. I'll reopen it this one time, but in the future this won't be good enough. You wouldn't hand in homework this i...
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3 months ago
Comment Post #282585 This question is closed because the diagrams are unreadable. You should have been able to see that for yourself. Each circuit should probably be a separate image, and any text between should be normal text in the question. Text in images doesn't work for indexing and searching. While you're at it...
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3 months ago
Edit Post #282585 Question closed 3 months ago
Edit Post #282575 Post edited:
3 months ago
Edit Post #282575 Post edited:
3 months ago
Edit Post #282575 Initial revision 4 months ago
Answer A: Battery voltage: to boost or to connect in series.
To summarize the problem, you have 12 V battery packs that you don't want to change due to certifications, but you need to power a 48 V 4 A load. The battery system also needs to be compatible with an existing charger that is meant to charge each of the 12 V packs with the negative ends tied togethe...
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4 months ago
Comment Post #282572 You say the electronics needs 4 A at 12 V, and that it has been redesigned to use "up to" 48 V. Can it still run from 12 V? You say one option is to increase the 12 V to "48V and 4A". Does the new redesigned circuit now require 4x the power? Why not 48 V and 1 A?
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4 months ago
Edit Post #282545 Post edited:
4 months ago
Edit Post #282545 Post edited:
4 months ago
Edit Post #282545 Initial revision 4 months ago
Answer A: Trouble understanding how to use adjustable LDO regulator
Your question is quite long, so it's not clear what exactly you are asking. It seems the main point is what Microchip means by Note 5 on page 7 of the datasheet: You are right, that makes no sense. Fortunately it's so clearly inconsistent with itself that you know it's wrong. Not all datash...
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4 months ago
Edit Post #282363 Post edited:
4 months ago
Edit Post #282363 Post edited:
4 months ago
Edit Post #282363 Post edited:
4 months ago
Edit Post #282363 Post edited:
4 months ago
Edit Post #282363 Initial revision 4 months ago
Answer A: Help with differential to single ended voltage converter
First, let's draw the schematic properly so that it's not so annoying to look at: Yes, it's a differential amplifier. Q1 sinks current as a function of VIN+. Q3 and Q4 are a current mirror that takes the current sunk by Q1 and dumps a current of the same magnitude onto Q2. When VIN- is a li...
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4 months ago
Comment Post #282265 @Carloc: If you feel something is wrong and downvote, the author really deserves an explanation unless it's just a crackpost post (which I think we can agree is not the case here). That way the author knows what to address and who to ping in case the error is fixed (so that the downvoter can undo th...
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4 months ago
Comment Post #282288 Why was this downvoted? The author has clearly put some effort into this answer. If he got something wrong, then he should at least be given the courtesy of being told what that is. Sorry I can't help here. These battery details are beyond my expertise, so I'm not voting either way.
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4 months ago
Comment Post #282265 Why did this get downvoted?
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4 months ago
Edit Post #282266 Initial revision 4 months ago
Answer A: Unexpected phase shift in results
I get a phase shift of 90 degrees between voltage of the capacitor and current through the capacitor which doesn't make sense it should be 45 degrees You don't need a whole circuit to see that the phase shift should be 90&deg;. You can see that from a capacitor in isolation. The current thru a...
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4 months ago
Comment Post #282194 @Dave: Good point. You should write an answer with that. Another way of looking at this is that the equation of capacitor voltage as a function of driving voltage will have a state variable. That state variable represents the charge on the capacitor.
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4 months ago
Edit Post #282194 Initial revision 4 months ago
Answer A: Current and voltage in AC circuits without impedance
Since this is homework, I'm not just going to give you the answer. When all else fails, go back to first principles. That's what handy shortcuts, like using impedance, were derived from. In this case, you'll end up with a system of differential equations. You have already written the equation...
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4 months ago
Comment Post #282160 @leventov: There are so many opinions out there, it's way beyond us to judge which are best. We leave the presentation to the authors. The help only tries to give guidance on what the content and level of detail of a paper should be.
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4 months ago
Comment Post #282160 @manass: I agree that a writeup about driving LEDs would make a good paper, as long as the detail is sufficient, and the underlying theory is explained. The equivalent of two printed pages would probably be a good minimum length.
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4 months ago
Edit Post #282160 Initial revision 4 months ago
Answer A: Questions about the style of "Papers"
say that materials should be small and focused There are many many theories of how to best present information. Any one or two particular opinions aren't really relevant, especially since there is a such a broad range available. The point of what you quote was mostly to set the expectation tha...
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4 months ago
Comment Post #282154 I don't know what you mean by "kinetic" in this context. Surely you don't mean the inertia of ions travelling thru the electrolyte. There is a significant voltage step from charging a cell at 1C, to immediately after disconnecting the cell. In other words, the cell exhibits some effective series r...
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4 months ago
Comment Post #282154 @coquelicot: The inner workings of electrical components is on-topic here. I don't know how many people that visit here have the expertise to answer this question, though. Most of it is over my head. It would be good to have some electro-chemical experts here.
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4 months ago
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4 months ago
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4 months ago
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Answer A: Meaning of some components around voltage reference in SMPS
At first glance, R22, C22, and C23 look like a compensation network around the TL431. However, this doesn't make much sense because the TL431 is being run open loop. Rfbt and Rfbb divide down the output voltage. The TL431 is turned on when that reaches 2.5 V. The TL431 is therefore used to compar...
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4 months ago
Edit Post #282139 Initial revision 4 months ago
Answer A: Contactor control - Higher voltage PWM
Your basic idea is fine, but your implementation is not. C1 makes the whole thing not work, as it will block DC. C2 puts a burden on the switch. D1 would preferably be Schottky. I'll write a more detailed answer when I have time, probably tomorrow. I'm back now and have more time to answ...
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4 months ago
Comment Post #282053 @Lundin: Actually the right kind of box doesn't need to be large. The walls can be in the near field as long as they appear as more space to the antenna. There are actually RF boxes built on this principle. You need just the right ferrite tiles so that the walls have the same 377 &Omega; impedance...
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4 months ago
Comment Post #282053 @Lundin: No, a "metal box" around an antenna would have a major effect on the antenna if in the near field, and would reflect the signal from the antenna back on itself if in the far field. If that metal box were lined with ferrite tiles, then it can work at some frequencies. You have to carefully ...
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4 months ago
Edit Post #281974 Initial revision 5 months ago
Answer A: Is there a way to reliably measure antenna return loss outside a lab?
It sounds like you are doing the measurements right. However, I expect the problem is in the space around the antenna. At 434 MHz, the wavelength is 690 mm or 27 inches. Everything out to about a meter or 1&frac12; m should be considered near field, and can effect the antenna directly. This inc...
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5 months ago
Edit Post #281970 Initial revision 5 months ago
Answer A: What is the popular 12 V DC jack connector?
There is no "standard" 12 V DC jack. Asking end users to buy a separate power supply is asking for trouble. Don't expect users to know about center-positive versus center-negative, and inner and outer barrel diameter. If this is an OEM product, then you can provide binding posts or even just lab...
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5 months ago
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5 months ago
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Answer A: What is the purpose of paralleling capacitors on the input/output of a power converter?
Lower ESR can sometimes be a reason, as you say. However, most of the time the advantage is a wider frequency range over which the combined capacitor has low impedance or low dissipation. The frequency capability of a capacitor depends on its type, and generally reduces with higher capacitance. ...
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5 months ago
Comment Post #281549 @coq: It is not evident at all how pins are connected when not shown. To show an unconnected pin, show it with nothing connected. The quality of a question is *always* relevant. When volunteering, it is totally the volunteer's call as to what constitutes wasting of time.
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6 months ago
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6 months ago
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Answer A: Is this AD8307 fake?
I am not familiar with that chip, and only took a very quick look at the datasheet. Here is the block diagram of the part from the top of the first page: A few things pop out from this: This chip has a differential input on pins 8 and 1. You tied the negative input to ground via a cap, bu...
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6 months ago
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6 months ago
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Answer A: Estimating the input capacitance of an BLDC motor controller
What is seems you really want to know is how to size a power supply filter capacitor, not what the input capacitance of something is. The objective is to keep the ripple voltage below some value. To determine ripple voltage, you need to know the characteristics of what charges the capacitor, and ...
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6 months ago
Comment Post #281478 The title asks about input capacitance, but then the body seems to be asking about a power filter capacitor. What are you really asking, and what is a "BLDC inverter"? BLDC is common for "brushless DC" motor. Do you mean a controller or driver for such a motor? What is "inverter" supposed to tell...
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6 months ago
Comment Post #281444 @Kran: My point is that it doesn't matter either way if the design was tweaked experimentally until it produced the desired result. Square versus curved is then just an implementation detail.
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6 months ago
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Answer A: Why are antenna PCB traces square instead of rounded?
PCB antennas are not designed by electrical engineers, but guys with pointy hats and wands They use trial and error after starting with the result of some mystic ritual including lots of mumbling and waving of the afore-mentioned wand. OK, that's not completely fair, but there is still a high com...
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6 months ago
Comment Post #281364 @Mu3: Remember that the FET likely has a body diode.
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6 months ago
Comment Post #281353 @Curious: You'd have to see what the manufacturer says. As for the 50 &Omega; to power, that is probably for impedance control, assuming 1:1 transformer ratio.
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6 months ago
Edit Post #281364 Initial revision 6 months ago
Answer A: Design considerations for a synchronous DC/DC converter
First, let's clarify something: replacing a diode with a MOSFET switch I have never seen the diode actually replaced. The intent is to have the FET on only when the diode would conduct, but no such timing is perfect. Having an actual diode there allows falling back to the classic case when th...
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6 months ago
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Answer A: How could you model a 10M/100M Ethernet PHY architecture?
I'm not going to get into how to model the PHY interface, but will try to explain why there are differences. The type of Ethernet you are talking about is transformer-coupled. The line itself is a differential pair with 50 &Omega; impedance. However, since a transformer is supposed to be between...
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6 months ago
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6 months ago
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Answer A: Why is the resistance of water so high?
Pure water does indeed have very high resistivity (different from "resistance"). Reasons water is dangerous around electricity include: Even small amounts of impurities greatly increase the conductivity of water. The water that you worry about that might contribute to a shock hazard is especia...
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6 months ago
Comment Post #281323 You need to check your math. 110 V across 500 k&Omega; causes much much less than 200 mA.
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6 months ago
Edit Post #281307 Initial revision 7 months ago
Answer A: Can you call an IC pin 'N.C' if it has hidden functionality?
Manufacturers can call their IC pins whatever they like. NC stands for "No connection", as the datasheet even says. There is nothing wrong with that. The only questionable part is "Must be connected to ground" for a pin that is not connected to anything. Without further explanation from the m...
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7 months ago
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Answer A: Max V/Hz value for motor
Here is a copy of your specs to make them easier to discuss here: None of those specs really tell you what the V/Hz of the generator inside that motor is. We could take a reasonable guess at if we knew that all the "Rated …" specs were at the same operating point, but that's not clear. What ...
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7 months ago
Comment Post #281289 What do you plan to do about it even if you do find datasheets?
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7 months ago
Comment Post #281274 Nice answer, +1. However, there were ICs well before the 1990s. You may be surprised to find that even back in the 1960s we had sliced bread, flush toilets, and integrated circuits.
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7 months ago
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7 months ago
Comment Post #281083 You originally said this was a radio. Now you say it's a transmitter. Which is it?
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7 months ago
Edit Post #281096 Initial revision 7 months ago
Answer A: Why is it is always power consumption or power delivered more in usage?
Power makes sense for steady state conditions. A certain energy will be used over one second. Then the same energy will be used the next second. And the next second. If I told you that such a circuit used 3 J, the first thing you'd ask is "When?", "Over what time?". Only knowing that is used 3 J...
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7 months ago
Comment Post #281083 Something doesn't make sense. Why do you care about harmonics at the antenna level? Surely your tuner will filter those out anyway. As long as the antenna resonates well and has the right impedance at the desired frequency, why do you care how much it picks up harmonics too? The first tank circui...
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7 months ago
Edit Post #281066 Initial revision 7 months ago
Answer A: Is there a particular type of lead-free solder that does not degrade soldering tips?
A different type of solder, other than using lead-based solder, is probably not going to help. There are two causes to your problem: Crappy tips. Higher temperature required due to lead-free solder. You can fix the first by getting a good soldering tool. Leaded solder will help with ...
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7 months ago
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7 months ago
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Answer A: How building a follower satisfying rather extreme requirements.
I don't have a real answer. This is just a suggestion for how to proceed. Look for amplifiers intended to drive 50 &Omega; cable. Sometimes the term line driver is used, even though that also means other things. If you only needed a few 100 MHz, a video line driver might work, but finding somet...
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7 months ago
Comment Post #281021 It really should be obvious that discussion of *"temporarily not be able to use something"* (like digital currency) has nothing to do with electrical engineering, and is therefore off topic here.
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7 months ago
Comment Post #281021 It is rambling in the sense that its not related to EE. Asking about characteristics of EMP is reasonable. Theory of electricity can be applied to the answer. It might be reasonable to ask how specific devices are effected by EMP, like computers. We don't care what those computers are running, th...
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7 months ago
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Answer A: Can there be a global EMP disaster, whether totally natural or partially natural and partly artificial?
EMPs (electro-magnetic pulses) occur naturally often. Every lightning strike is one example. Larger EMPs have been created artificially with nuclear weapons. The Starfish Prime H-bomb test caused damage a long way away in Hawaii. There were cases of the wires in street lights getting fused by t...
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7 months ago
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7 months ago
Comment Post #281021 The first part of your question at least is an electrical and physics issue. The rambling about digital currency doesn't make much sense, doesn't actually ask a question, and isn't about electrical engineering. This is why I am going to delete it.
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7 months ago
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8 months ago
Comment Post #280927 @2kind: LEDs usually can't tolerate much reverse voltage either. D2 is not strictly needed according to your specs. If you're fine with the absolute minimum input voltage being whatever the maximum B-E reverse voltage is of the transistor, then you can leave out D2. However, stuff happens, and D2 ...
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8 months ago
Edit Post #280927 Initial revision 8 months ago
Answer A: Isolated Digital Input - Overvoltage protection
To summarize, it seems you want a circuit that will detect an input voltage high/low with a threshold somewhere between 0 and 3.3 V, must operate correctly with 0-3.3 V input, but must tolerate input up to 32 V. Snap action (hysteresis) is not required. An opto-isolator is to be turned on when the ...
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8 months ago
Comment Post #280893 *"When input is low, the opto should be off therefore “PIN_PROG_1” should be high"* This makes no sense. When the opto is off, PIN_PROG_1 will be low because it will be pulled down by R73. You can always flip polarity by how the opto output is connected. The opto should be off for the input polari...
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8 months ago
Comment Post #280893 What do you mean by "active low". Should the opto be on when the input is low? You need to specify the full input range (you seem to have only specified the maximum), and what the function of input to output is. What threshold voltage? What input impedance is required? Is a gray area allowed, or...
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8 months ago
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8 months ago
Edit Post #280873 Initial revision 8 months ago
Answer A: My grid dip: how does this electron tube technology work?
The video helped explain a few things, but it's still not clear what the overall purpose of this device is. You showed it clearly producing a signal, but the documentation you quote talks about an incoming signal. The meaning of the current shown on the meter is unclear, and so is the function of t...
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8 months ago
Comment Post #280870 Half that page has some foreign script, like Arabic or Hebrew. Besides, I don't want to read a whole manual. *You* should explain in a paragraph or so what this thing is supposed to do, what the user interface is, etc. I've never heard of a "grid dip" before, and certainly have no idea what you th...
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8 months ago
Comment Post #280870 The schematic is pretty hard to read. A better scan at higher resolution would help. It would also help to explain what this device is supposed to do, and what external connections have what properties. It looks like it has pluggable modules at right, some sort of oscillator, and a control to adju...
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8 months ago
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8 months ago
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Answer A: What is causing this massive discharge traveling down a power line?
It is hard to know from a single static low-res picture, but my guess is that something caused a short across the high voltage lines. That could be a falling tree limb, a squirrel making an unfortunate hop, a bird with outstretched wings in the wrong place, some conductive debris blown across the wi...
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8 months ago
Comment Post #280791 It's a number somebody picked from a whole set of tradeoffs. Note that 3.3 V is just about 2/3 of 5 V.
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8 months ago
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8 months ago
Edit Post #280714 Initial revision 8 months ago
Answer A: Is it always necessary to use the ground terminal of the oscilloscope probe?
Yes, you should connect the scope probe ground to the circuit ground near where you are probing. The unit under test (UUT) and the scope may have their grounds connected, but that is via a round-about path. This causes problems: The ground path can have significant impedance at high frequencie...
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8 months ago
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9 months ago
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Answer A: Name of this current limiting device
Your circuit It doesn't make sense that the yellow blob is a current sink: If it were a current sink, then there would be no point to the resistor in series with it. That only wastes power, reduces the compliance range, and doesn't change the current. You need to look at the whole circu...
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9 months ago
Comment Post #280626 What you say works well when there is virtually no startup torque, like with a propeller. For loads that require some torque to move at all, you need to slowly rotate the magnetic field so that the 90° condition of maximum torque is guaranteed to occur. After that you assume the rotor stays locked ...
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9 months ago
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Edit Post #280614 Initial revision 9 months ago
Answer A: Is a BJT 3-transistor Wilson mirror faster than a simple mirror?
First Circuit Let's start by looking at the conventional current mirror circuit: The base of Q1 (Not sure which one that is? Use component designators next time!) is driven to whatever it takes to pass the current dumped onto the collector. Q2 is assumed to have identical properties, so it...
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9 months ago
Edit Post #280609 Initial revision 9 months ago
Answer A: BLDC motor - initial rotor position
This is usually done by driving the motor very slowly open loop at startup. The idea is that the rotor will follow the magnetic field. Once you think the rotor is in sync with the drive, you speed up the drive and look for the back EMF. Since the magnitude of the back EMF is proportional to speed,...
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9 months ago
Comment Post #280600 We don't know what you think a "half-Wilson" mirror is. If you want to compare two circuits, show the schematics of both of them. Also the current would be a step, not "ramping" up and down. Do you mean the *voltage* ramps up and down to nearly both rails?
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9 months ago
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9 months ago
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Answer A: Why are two identical filters required for each signal, if the signals can be multiplexed into a single filter?
There are a number of things that are unclear. You talk about the red and IR phases of the light sensor signal being demultiplexed into separate red and IR signals, but there is no evidence of this in what you show. If this is happening at all, the crucial information of what each filter is driven ...
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9 months ago
Edit Post #280589 Initial revision 9 months ago
Answer A: Why does AC frequency affect my microwave's RPM?
The turntable is apparently run by a cheap synchronous motor. There is a type of motor that's easy to manufacture, that turns synchronously with the line frequency. You say the table used to rotate at 6 RPM with 60 Hz power, and now rotates at 5 RPM with 50 Hz power. That is exactly what you'd e...
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9 months ago
Comment Post #280582 What documentation you need is already dependent on individual posts. If this site was getting 10s of questions per day, I wouldn't mind a new category. However, with the current volume it will only highlight the fact that there is low activity here. Look at what too many categories did to the Pho...
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9 months ago
Comment Post #280582 I agree with what you said, but don't think a new category is necessary. These questions can already be asked in the main Q&A right now. The volume there is quite low now. If we ever get overrun, we can think about a new category then.
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9 months ago
Edit Post #280566 Initial revision 9 months ago
Answer A: How about a new section for code reviews?
Personally I wouldn't want another category (what you seem to mean by "section"). I also don't think this should be a code review site. However, asking for validation and advice on small and specific pieces of code is already on topic, if that code is somehow related to hardware. For example, ...
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9 months ago
Edit Post #280538 Initial revision 9 months ago
Answer A: MOV vs TVS diode
You really have to compare datasheets. There are some general differences, but you shouldn't go by those in specific instances. MOVs usually have softer knees, are available at higher voltages, and are available for dissipating higher powers. Usually. One drawback of MOVs that they get "used up...
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9 months ago
Edit Post #280532 Initial revision 9 months ago
Answer A: Why is the Linear Time-Invariant System (LTI) dominant in Signal processing?
Linear systems lend themselves to analysis since they follow certain rules. Because of this, much analysis has been done and theory developed, so there is now lots to keep undergrads busy with. Many simple passive systems are linear systems, or close enough so that they can be approximated as suc...
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9 months ago
Comment Post #280450 @Lundin: The catching fire part was probably the visual effect of arcing. When the worker jumped out of the truck, he was probably still nearly touching it when he also touched the ground. This greatly reduced the insulating clearance, due to the body being essentially a conductor. The 700 kV jump...
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9 months ago
Comment Post #280450 Why the downvotes? Somebody has to design these things, and the voltage they run at must be a consideration. Asking about the design tradeoffs is totally legitimate.
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9 months ago
Edit Post #280458 Initial revision 9 months ago
Answer A: recommendation for chip programming connection (pogo?)
I have also had this problem for production runs of 100s to 1000 where you don't want to spend too much on a full fancy jig. Put plain round pads on the bottom of the board. 50 mils is usually a good diameter. Those work well with simple 90&deg; pogo pins. Don't use holes. In my experience, a ...
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9 months ago
Comment Post #280395 @Chup: That's not how data sheets work.
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9 months ago
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9 months ago
Edit Post #280398 Initial revision 9 months ago
Answer A: What should be considered when picking a flyback diode?
Catching a flyback pulse is actually a rather easy application for a diode. Many of the diode parameters don't matter much. The basics are: Reverse voltage. This is simply the maximum voltage the coil will be driven with, which is 24 V in your example. There is nothing magic about the flyback ...
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9 months ago
Edit Post #280395 Initial revision 9 months ago
Answer A: PCT2075 temperature sensor accuracy
The text values in the specifications section are always the real specs. Unless otherwise stated (and that's quite rare), graphs are suggested values, typical ranges, variations due to a single variable, and the like. They are NOT specifications. The only accuracy you can count on is what it say...
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9 months ago
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9 months ago
Comment Post #280344 Done. See https://electrical.codidact.com/posts/280357.
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10 months ago
Edit Post #280357 Initial revision 10 months ago
Question What should rep gain/loss be on Papers?
The Codidact team has recently informed us that it is now possible to have different rep bumps on different post types. See this new answer by Monica to the old meta discussion that created the Papers category in the first place. Papers were always intended to be significantly more substantial wo...
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10 months ago
Comment Post #280344 What's the rep change for votes now? Let's set the gain from upvotes to 3x that, and the decrease from downvotes to the same value (3x whatever upvotes are now, not 3x the current downvote decrement).
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10 months ago
Comment Post #280344 Also, do what is most convenient with the existing rep. I don't care whether the rep bump from the existing papers stays what it is now, or gets re-calculated as it if happened on the new post type. Whatever works best for you. The rep from a few papers shouldn't be that much in the overall scheme...
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10 months ago
Comment Post #280344 Thanks, that clears up some of my confusion. If it's easy to do, how about convert all posts in the Paper category to a new Paper post type, with ±20 rep per vote? &plusmn;30? I don't want this to be burdensome on you folks. It's a nice to have, but we are getting along well enough without it. Pa...
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10 months ago
Comment Post #280327 @Andy: Maybe, but in the top picture you can clearly see that the loop has no effect on the other cable. It may be just a parallax thing in the second picture. I'll try to get back there and take more detailed pictures from better angles.
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10 months ago
Comment Post #280344 If I understand this right (I got a little confused), you can't set the rep value of votes per category, but can per post type? Sounds strange, but I'm not a web developer. The proposal is then to create a "Paper" post type, and convert all existing posts in the Papers category to the new post type...
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10 months ago
Edit Post #280327 Initial revision 10 months ago
Question Cable loops between utility poles?
Sometimes cables between utility poles make a loop and do a U-turn. What is the purpose of such loops? The loop I'm asking about is in the lower set of wires towards the left of the picture. These must be communication cables. The 3-phase power is clearly evident at the top of the pole. ...
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10 months ago
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10 months ago
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Answer A: is this too obvious for a post?
This sounds like it could be a Paper (https://electrical.codidact.com/categories/35) if written up nicely. It doesn't make sense as a question because you're telling, not asking. I haven't heard of this idea before, and I have definitely not used it. It sounds like rather a cute trick. You shou...
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10 months ago
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10 months ago
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Answer A: Confused about the amplitude and shape of output voltage pulse
Coquelicot's answer explains what is going on, so I won't duplicate that. However, one of the sources of confusion is that you are looking at the two waveforms in isolation. Your scope obviously has at least two channels, since we can see a unused blue line in each picture. Use both channels. ...
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10 months ago
Comment Post #280040 I just noticed that too this morning, +1. Hopefully someone can fix this.
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10 months ago
Edit Post #279988 Initial revision 10 months ago
Answer A: CAN Bus - Internal Oscillator
You are making this too complicated. The only thing that matters is the percentage mismatch between any two clocks on a CAN bus. You seem to imply that you are willing to guarantee the -10 &deg;C to +85 &deg;C temperature range, so the oscillator will be within -1.9% to +2.3%. Any two devices co...
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10 months ago
Comment Post #279969 Or just Shottky diodes to ground and the A/D supply. The Shottkys should kick in before the protection circuitry of the A/D. With a normal silicon junction drop, the internal protection circuitry might take most of the load.
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10 months ago
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10 months ago
Comment Post #279967 Your continual small edits are getter rather annoying, as they keep pushing old questions to the top of the active list. Give it a rest already!
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10 months ago
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Answer A: Transformer - Vsec or Current rating parameter
In addition to what Andy said (+1), the 350 mA AC figure is probably limited by power dissipation, and therefore temperature. It applies during normal forward operation where the secondary current "unloads" the core as fast as the primary current tries to load it. The 11 V&sdot;&micro;s figure is...
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10 months ago
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Answer A: Driving ADC with opamp with large rails
Is the risk too great? That depends on parameters you haven't told us. How cost-sensitive is this product? What is the reliability expectation of the users? How mission-critical is its usage? For example, if this were a toy, I'd say screw it and look for a way to not even buffer the signal i...
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10 months ago
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10 months ago
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Edit Post #279886 Initial revision 10 months ago
Answer A: ESD USB Shield Connection & Filtering
Your question is impossible to answer without carefully looking at the layout and schematic. However, from gut feel and experience, this smells like poor grounding design. Common mistakes: Not a single board-wide master ground plane. Too many large islands in the ground plane. The metric o...
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10 months ago
Comment Post #279860 *"can not upload pictures"* is too vague. You should describe exactly what you did, and what the response of the system was. Also, this probably belongs on main meta, where it will likely get more visibility.
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10 months ago
Comment Post #279819 @2kind: I'm not sure what you mean. There is little difference. Perhaps you are asking about them being stable. They are inherently stable in that they won't run away with oscillations of increasing amplitude. That doesn't mean they can't still be meta-stable with a lower frequency on the output ...
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10 months ago
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10 months ago
Comment Post #279816 @Andy: I took that to mean that the point of this circuit is to be an isolated power switch. POWER_IN would be the incoming supply, and POWER_OUT the line being the switched. Presumably the load would be connected between POWER_OUT and some "POWER_RETURN" that is not shown. Perhaps the OP can clar...
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10 months ago
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10 months ago
Edit Post #279819 Initial revision 10 months ago
Answer A: Flyback Converter - Output Ripple
Ripple doesn't need to be that high. I've done flyback supplies to power isolated sections quite a bit, using a pulse on demand scheme like yours. It's not hard to get the ripple down to &plusmn;50 mV. Usually the ripple is within &plusmn;100 mV even when you don't do anything special to minimize ...
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10 months ago
Comment Post #279803 @dust: Then you have a broken Roomba. Get a new one. This is not something you can fix.
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10 months ago
Edit Post #279803 Initial revision 10 months ago
Answer A: How can I debug, (and eventually fix) this Roomba PCB?
The charger is supposed to output 20V-24V when the roomba is plugged in. However it's only showing 1.6V. If this is really true, then there is no point going further. The charger isn't working, the Roomba got discharged, and now wont run because it can't be recharged. However, it's not clear w...
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10 months ago
Comment Post #279785 @Pac: Your second question doesn't make any sense, so I ignored it.
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10 months ago
Edit Post #279786 Initial revision 10 months ago
Answer A: Can I ask about debugging/fixing a broken product?
Repair questions can be on topic if it's about the underlying electronic principles. Just "How do I fix this?" is off topic. There is little wiggle room for trying to repair a consumer device that you don't even have the schematic for. That doesn't mean you can't, but that such questions are har...
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10 months ago
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Answer A: digital multimeter display count range
Digital voltmeters generally display decimal digits. The resolution implied by that is not necessarily the same as the underlying binary A/D. Since voltmeters for human display don't need to be fast, but high resolution is good, these usually use delta-sigma A/Ds inside. These can have 20 or mor...
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10 months ago
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Answer A: Cleaning flux out of USB connectors after soldering
Direct answer How to clean off flux depends on what type of flux was used. Most electronic parts can handle being washed in clean water. In fact, boards often go thru what amounts to an industrial dish washer after soldering. If water soluble flux was used, then this will probably work. Chec...
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11 months ago
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11 months ago
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Answer A: High Power Switch - High Side vs. Low Side Switching
It's still unclear what you are really asking, so I'll discuss the tradeoffs between low and high side switching of power to a load. Low side switching The main advantage of low side switching is that controlling the switch is easier. This is because the logic that decides whether the switch s...
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11 months ago
Comment Post #279728 That's a bit better, but brings up other questions. Why are there two different FETs back to back for the switch? Where is the load? You mention communications interfaces, but none are shown in the schematics. What's the point of the current sources (I1 and I2 in your schematics)? You also have ...
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11 months ago
Comment Post #279728 There is way too much hand waving here. Draw a block diagram, and define your terms. We don't know what you think a "LVD domain" and a "PMSM inverter" are. And what is "1.000,00 uF" supposed to mean? Is that really 1 uF to absurd precision, or some screwup with commas and points?
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11 months ago
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Sentences start with upper case letters.
11 months ago
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11 months ago
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Answer A: What is the role of the differential amplifier in a delta sigma converter?
Your question really comes down to how a delta-sigma A/D works. The A/D internally models the input voltage with a stream of bits. Each bit can only indicate the minimum or maximum voltage. The aim is to make a stream of bits that in the aggregate when averaged together accurately represent the ...
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11 months ago
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11 months ago
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Comment Post #279602 Various things are still missing. All the answers to https://electrical.codidact.com/questions/279585 is one obvious example. Note that the question list says "3 answers" (which seems correct from memory), but there are none in the question itself.
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11 months ago
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Answer A: What is the difference between differential amplifier and differentiator?
A differential amplifier and a differentiator are two completely different circuit blocks. Differential Amplifier A differential amplifier has two inputs and one output. It takes the difference between the two inputs, multiplies that by the gain, and makes it the output. &nbsp; &nbsp; Out =...
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11 months ago
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Removed fluff. To thank people, upvote answer if you think they are good.
11 months ago
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11 months ago
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Answer A: Are questions about proper cable repair on-topic?
Lundin's answer notes: I just realized that the on-topic page https://electrical.codidact.com/help/topics doesn't address electronics assembly. It does now. I just added: Physical construction of circuits or electrical products, within limits. This is generally on topic when there is some e...
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11 months ago
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11 months ago
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11 months ago
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Answer A: Bit-rate vs Baud-rate
Baud rate is about the speed of bit slots in the channel or symbols. Bit rate is the rate at which actual data is transmitted. Put another way, baud rate is what you see when you look at a scope trace of a communication signal. Bit rate is how fast data gets from one end to the other. The bit...
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11 months ago
Comment Post #279413 **Inappropriate comments deleted.** Comments are not for content, and certainly not for chatting between two users who didn't even write the answer the comments are under. **Knock it off already!** If you want to explain to someone what a "load line" is, or anything else for that matter, put that ...
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11 months ago
Comment Post #279431 Good circuit, +1. However, I'd break the pot up into a fixed resistor for the top part, and a pot to only allow up to a volt or so max for the bottom part. That reduces the settings that might cause damage, in addition to giving you higher adjustment resolution. With 100 kOhm fixed and a 10 kOhm p...
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11 months ago
Comment Post #279402 **Question cleaned up, and comments that became a discussion deleted**. tlfong01, don't get used to others cleaning up your questions for you. This site is for questions and answers, not long winded side stories or discussions. Let this be an example of how you should have asked. Others, if you ha...
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11 months ago
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11 months ago
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Answer A: How to plot the I-V curve of a tunnel diode?
Apparently you want to measure the current/voltage relationship of a tunnel diode. The tricky part is that the voltage isn't unique for currents over parts of the range. From your question: Image Note that the current is still unique as a function of voltage. One solution is therefore to swe...
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11 months ago
Edit Post #279285 Initial revision 11 months ago
Answer A: Creating an additional "user"
Personally I'd rather have everyone use their real name and affiliation. That basically puts their reputation out there on anything they say. If you really believe in something, have the guts to say so. If you don't, then I don't want to hear it. However, that's not the policy of the site. I w...
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11 months ago
Comment Post #279103 @Lundin: Feedback needs to be public so that everyone can see what the norms are, and that they are applied fairly. I certainly don't want to explain why 20 similar post are too broad, when doing it only a few times may head off the others. If you can't handle being publicly criticized, then you do...
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11 months ago
Comment Post #279250 What you call "confrontal" is bluntness, and somewhat deliberate. Experience elsewhere has shown that subtlety is merely an invitation to ignore the content.
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11 months ago
Comment Post #279103 One thing that helps to address this issue is to have reasonably good explanations of why the question was closed. In the particular case cited, I think the close text explains the situation reasonably well. If users genuinely want to understand what is wrong with their question, they will find sup...
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11 months ago
Edit Post #279104 Initial revision 11 months ago
Answer A: Please find other ways to hide inloved questions that prompt close
I have boycotted the SE and neither asked or answered any questions so am happy to have a new home here. I'm glad you're here. You might also want to mention this in your SE profile, and point people here. For example, see my profile on SE. Also I believe that my and many others who have call...
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11 months ago
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11 months ago
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12 months ago
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Answer A: Using FET based followers and design rules
FET source-followers are generally less predictable than BJT (bipolar junction transistor, like NPN or PNP) emitter-followers. An emitter follower output is one diode drop below the input. The voltage across a diode varies little as a function of the current, so this offset remains fairly constan...
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12 months ago
Comment Post #279010 @Circ: No, a little positive feedback doesn't make it a latch. It adds hysteresis. The more positive feedback you add, the larger the hysteresis interval.
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12 months ago
Comment Post #279016 All your schematics except Fig 7 are basically unreadable again. You seem to think all those lines "show" things, but they really clutter up the drawing and make it hard to see the circuit under all that mess.
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12 months ago
Comment Post #279010 @Circ: No, what he "invented" was just a comparator with a lot more parts than necessary.
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12 months ago
Edit Post #279010 Initial revision 12 months ago
Answer A: ESD Protection - Differential Amplifier
Not a diff amp Something doesn't make sense here. You want A1A to act as a differential amplifier, but that's not how you wired it: Image Here is a real diff amp: Image Note how the right side of R1 is tied to ground, not the opamp output. The diff amp above is really a 3-input cir...
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12 months ago
Comment Post #278989 What "TVS diode"? I don't see a TVS anywhere in that schematic.
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12 months ago
Comment Post #278984 @Lundin: How a question is worded and what exactly it is asking significantly influences whether answers will be opinions. A good question that someone answers with opinion isn't necessarily the fault of the question, but we want to avoid questions that basically solicit opinions and speculation.
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12 months ago
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Answer A: Are questions about electronics market trends on-topic?
It could be OK if you are asking about technology reasons why a class of products will be phased out. Asking about forces that cause similar things in the past should be OK too, as long as the reasons can really be known. For example, asking why transistors replaced tubes is fine since good techn...
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12 months ago
Comment Post #278933 It is hard to see the circuits from your schematics with all those lines in them. There is just too much clutter all around.
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12 months ago
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Answer A: Why is the ACK (acknowledge bit) in the CAN bus frames dominant? What could have been the rationale behind that design decision?
In addition to what Lundin said, making ACK dominant means that something out there is actively responding, and that response is affirmative. If ACK were recessive, then the transmitting node being totally cut off from everything else would appear like no error. Put another way, without an active...
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12 months ago
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12 months ago
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Answer A: Microwave oven interfering with WiFi on the 2.4GHz band
Microwave ovens work on the frequency they do because that's one of the main resonant frequencies of water molecules. The radiation excites water molecules, which then transfer some of their extra energy to other surrounding molecules. No, microwave ovens are not intentional radiators, at least n...
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12 months ago
Comment Post #278819 **Note to commenters:** This is not the place to discuss what kind of scopes you have and what they are good for. First, that doesn't belong in a comment at all. Second, the issue here is what might be on topic on the main site, not about scopes.
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12 months ago
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Answer A: Name of the OP in the list of questions
What you ask is not specific to the Electrical Engineering site. There is nothing we can do about it here. If you really think this is a good idea, then you should propose it on the main Codidact meta site.
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12 months ago
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Answer A: weak WiFi when microwave is running
The microwave oven uses frequencies near some types of WiFi. The very strong radiation created by the oven is meant to stay inside the oven. However, even if only a small fraction gets out, it could easily overwhelm the relatively tiny WiFi signals. This could actually be indicating a potentiall...
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12 months ago
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Answer A: Can recommended features questions be asked?
I think this could be on topic if done carefully. We don't want this to devolve into a popularity contest of everyone's favorite features. Answers also can't be about opinions of which features "everyone should have" in general. If you describe a particular application, it could be appropriate t...
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12 months ago
Comment Post #278793 This is meta, so downvotes only mean disagreement. No big deal. You also don't know who voted and which way they voted. In this case, the user with the obnoxious name with blanks and two dots (that should be disallowed) was being snarky (no real harm in that), but you can't assume he downvoted, or...
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12 months ago
Comment Post #278760 @LvW: You are asking about many different circuits, and mixing two different concepts into the same question: Whether people recognize the names you used above to know the circuits, and whether they know of real life uses for those circuits. That's too much for one question, and makes the composite ...
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12 months ago
Comment Post #278760 @LvW: I've already told you what to do if you want to know what common applications a particular device has.
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12 months ago
Comment Post #278760 @LvW: So you're really asking if anyone recognizes the names or abbreviations. They may have used a circuit like that, but be unaware of what you call it. However, that's not how your question reads. It's written implying we are all supposed to know what those names mean.
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12 months ago
Comment Post #278616 Extended discussions in comments deleted. If you want to argue technical points, put them in your answers.
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12 months ago
Edit Post #278760 Question closed 12 months ago
Comment Post #278760 This question is too broad, and the answers will be vague at best since "significance" is very subjective. In addition, the circuits you ask about need to be defined, preferably with schematic. These names aren't standard, or at least not in common use. It could be OK to have each circuit in a sep...
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12 months ago
Comment Post #278670 @Peter: Then I'd have to read and vet his articles first. I've done measurements too.
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12 months ago
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12 months ago
Comment Post #278718 @manas: Yes, the power dissipation of multiple resistors do add, assuming they are spaced far enough to not significantly heat each other. The voltage rating also adds when the resistors are in series. However, the question wasn't about either of these.
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12 months ago
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12 months ago
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Answer A: More accuracy from multiple resistors in series or parallel?
The worst case won't get any better, whether series, parallel, or some other combination. The result of two 1 k&Omega; &plusmn;5% resistors in series is a 2 k&Omega; &plusmn;5% resistor. The probability that the result is closer to the middle gets better with multiple resistors, but only if ea...
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12 months ago
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Question More accuracy from multiple resistors in series or parallel?
What happens to the overall accuracy of a resistor if I implement it as multiple resistors in series or parallel? For example, can I get better than 2 k&Omega; 5% by putting two 1 k&Omega; 5% resistors in series? Or are two 4 k&Omega; 5% resistors in parallel better? Is there some way to use mul...
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12 months ago
Comment Post #278707 Unfortunately all too often X can't really deliver 3-6 months faster. They are misleading the customer to get the job, figuring they'll get the extra later when the customer is already committed and can't easily go back to a more honest contractor.
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12 months ago
Comment Post #278707 I generally agree, except that how competitors are perceived to perform should NOT be part of any estimate. For estimates to be useful, they need to be honest assessments, and not based on wishful thinking. That causes much trouble later in the project.
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12 months ago
Comment Post #278703 I don't think it's worthy of a downvote, so have an upvote from me.
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12 months ago
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12 months ago
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Answer A: How to estimate time of completion while developing an electronic product?
There is no easy answer to time-estimation. Experience is essential, but even for experienced people it's never easy. For simple projects, like designing a DC-DC converter inside some larger product, it comes down to having done it before and using that as the starting point. After a while, you ...
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12 months ago
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Answer A: De-bouncing input signals?
Bouncing signals When a mechanical switch opens and closes, there is often vibration in the contacts so that they open and close several times rapidly until the new steady state is eventually reached. Bouncing is perhaps easier to visualize for a switch closure. Two conducting things (conta...
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12 months ago
Edit Post #278669 Initial revision 12 months ago
Question De-bouncing input signals?
I've heard that input signals to digital circuits should be "de-bounced", at least sometimes. What is de-bouncing? Why is it needed? When is it needed? What is bouncing around in the first place?
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12 months ago
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Answer A: Why Ib=const. for BJT output characteristics Ic=f(Vce)
Getting into wars about whether something is current controlled or voltage controlled is pointless. In most cases, there is some of both going on. Which "one" to call it then has more to do with personal biases than physics. However, the real answer is that we do electrical engineering here. Mo...
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about 1 year ago
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Comment Post #276137 @Circuit: The point is that what you wrote belonged in an answer, not comments. Papers don't ask questions, so answers don't make sense. Comments on papers can get a bit more into the paper content, but that has limits too. If you have something to say, you should be saying it in your own question...
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about 1 year ago
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Comment Post #278602 @manas: I was trying to be blunt in what someone's thought process would be. Some people need to hear that. Nobody is being called an asshole. Actually, in one place I had a bunch of characters (number sign, dollar sign, at sing, ampersand) like they show in cartoons sometimes, but something trigg...
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about 1 year ago
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Answer A: Rules and guidelines for drawing schematics?
A schematic is a visual representation of a circuit. As such, its purpose is to communicate a circuit to someone else. A schematic in a special computer program for that purpose is also a machine-readable description of the circuit. This use is easy to judge in absolute terms. Either the proper...
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about 1 year ago
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Question Rules and guidelines for drawing schematics?
We see schematics of varying quality and conventions. What is good and bad? What are the rules and conventions for drawing good schematics? What matters? What doesn't? This question is about schematics, not the circuits they represent.
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about 1 year ago
Comment Post #276137 @Circuit fantasist - Your comments were deleted. Content doesn't belong in comments. **Read the rules already!** If you have something to say that addresses the question, write it in an answer.
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about 1 year ago
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Answer A: Can I ask a question to which I have a possible answer?
Self-answered questions can be OK here. Those are best when they are canonical questions on topics likely to come up. Some examples where I have done this are: What is a bootloader, and how would I develop one? How to calculate pullup resistor value for pushbutton? In all such cases, t...
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about 1 year ago
Comment Post #278548 @Circuit: But that's not what you did. If you have an idea in mind that you want validated, *ask about it specifically*. What you really did was grandstanding masquerading as a question. This will **not be tolerated** in the future. Consider yourself on thin ice. Future questions that aren't spe...
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about 1 year ago
Comment Post #278548 @Circuit: If you already had a specific idea you weren't sure of, then why didn't you ask about that? If you already had an answer, then what was the point of asking the question in the first place? Either way, it seems you were just wasting other people's time.
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Answer A: Is it possible for one transistor to switch between two loads?
It's not clear what you are really asking, but here is something that might fit your requirements: Image First, R1 and R2 can be considered separate loads. The transistor therefore switches two loads. This circuit can also be used to produce two signals, one inverted from the other. This u...
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about 1 year ago
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Comment Post #278484 @2kind: The secondary already needs to put out a bit higher voltage than you actually want. You don't want to do every pulse in a pulse on demand system, since that means there is no margin for higher current demand. I have used a linear post-regulator a few times, usually not for reduced ripple, b...
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about 1 year ago
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Answer A: Control circuit for Power Converters
I'll assume by "PMIC" you mean a dedicated switching power supply chip. Such a chip contains the PWM generator and receives output voltage feedback at a minimum. They may also include a driver for an external FET as the switching element, include the switching element directly, include the diode wi...
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about 1 year ago
Comment Post #278478 Your original question asked "which is better". We don't do opinion-based answers here. I have edited your question to fit the site, else we would have to close it completely.
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about 1 year ago
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Fixed to make on-topic
about 1 year ago
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Answer A: Filtering the high frequency noise in switching PSU
A switching power supply already is inherently a filter. Current is coming thru an inductor, followed by a capacitor to ground. If you are asking what additional is usually done to filter out changes in the output voltage (not common mode, that's a totally different issue), then the typical answe...
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about 1 year ago
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Answer A: High Speed Design - Which grounding strategy to choose?
You are right in that at high speeds, like over 2 GHz, things are different than in "ordinary" circuits. The post of mine that you quoted was written in the context of such ordinary circuits. The lumped system approximation that is valid for ordinary boards fails at high frequencies. You have to...
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about 1 year ago
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Answer A: Why there is a body diode in mosfets?
in my engineering curriculum .. I never found a diode in a mosfet symbol Then you should ask for your tuition back, or perhaps the institution should want their diploma back. but in datasheets there is a diode called as body Right, because there is. It is possible to make such FETs without ...
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about 1 year ago
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Answer A: Filter Impedance Consideration
If I have a filter stage between an antenna and an LNA, wouldn't I want the load impedance(input to the LNA) to be large with respect to the source(antenna) in order to not attenuate the signal even further? Not necessarily. What you want is maximum power transfer, not maximum voltage. Power is...
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about 1 year ago
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Comment Post #278421 @coq: No need to edit the question. The note makes it clear enough what is going on.
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Answer A: I have to choose: Arduino or Raspberry pi.
This site isn't appropriate for telling you what to choose. We can, however, give you information on microprocessors versus microcontrollers. Microprocessors and microcontrollers are intended to different applications. As a result, they have different capabilities, and different tradeoffs of use...
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about 1 year ago
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Answer A: Mixers and Audio Extraction in a DCR Architecture
It seems your question comes down to how to demodulate a SSB (single sideband) signal. Note that the single sideband is already the signal you want, just shifted by some fixed frequency. One way to recover the original baseband signal is therefore to frequency shift it. This is usually done by m...
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about 1 year ago
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about 1 year ago
Comment Post #278354 The circuit you show has nothing to do with any "bootstrap" technique. Its a R-C low pass filter followed by a unity gain buffer. The rolloff frequency is 1/2πRC, which is 1.6 Hz for the 1 M&Omega; and 100 nF part values you cite.
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about 1 year ago
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Answer A: Is ESD overhyped?
Yes, damage due to ESD (electro-static discharge) is real. Just because you haven't seen it isn't much evidence of anything. Some obvious possibilities why you haven't observed the problem are: You failed to create a proper ESD event. You didn't measure the results properly. The built-in E...
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about 1 year ago
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Answer A: Purpose of emitter resistor in a common collector amplifier
First, let's nail down what circuit you are asking about. Your description is somewhat vague, so I picked this interpretation: Image Q2 is the emitter follower stage, driven by the previous common emitter stage of Q1. Your question seems to be why R2 exists. Some load is needed at DC to pu...
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about 1 year ago
Comment Post #277844 @Andy: Basically, using a PNP transistor around an LDO to detect input voltage high/low has been useful a few times, and I haven't seen it mentioned anywhere else. I may have generalized the problem too much so that it's not clear what the cute trick is. I should probably modify the *The Problem* s...
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about 1 year ago
Comment Post #278192 You really need to step back and look at the whole problem, not the details of one imagined solution to the higher level problem. You are apparently trying to measure electric fields. Ask about that directly in a separate question. In particular, explain what fields you are trying to measure, thei...
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about 1 year ago
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Answer A: How to define Vsat for MOSFET as a switch?
First, that's an archaic chip that requires a lot of circuitry around it to do anything useful. Why use this particular chip? Second, the datasheet gives you an example of how to use this part as a step-up converter with external switch. Why not follow that? Third, blindly following equations...
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about 1 year ago
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Answer A: High pass filter design
You are asking for a filter that passes 2% at 60 Hz and 99% at 90 Hz. That comes out to a transition of 97% of the amplitude within 0.6 of an octave, which is quite aggressive. The real answer My first reaction is that this smells like attempting to fix bad system-level design in the wrong pla...
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about 1 year ago
Comment Post #278161 @Lundin: Yes, I've been meaning to write up something about schematic drawing. I was originally going to add more to the SE post on that, but the mods turned it into community wiki and I lost control over it, so I gave up.
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about 1 year ago
Comment Post #278161 @Lundin: BOM optimizations are tricky because they can easily devolve to prices and vendors. That's probably why the question on SE was closed. I think our rules here are about the same as on SE. Maybe they just closed it quickly, or maybe it really did cross the line into prices and vendors. I s...
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about 1 year ago
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Answer A: Are BOM cost optimization questions on-topic?
Yes, some BOM optimization questions like you mentioned could be on topic. This would include the general techniques for optimizing BOM costs. Getting into specific prices and vendors would be off topic.
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about 1 year ago
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Answer A: Design considerations when using a wireless charging battery pack
There are various criteria that govern how well power is taken from a nearby changing magnetic field: Distance. The magnetic field diminishes rapidly with distance from the source. Shielding. Pickup ability. To get current from a changing magnetic field, there has to be a conducting loop w...
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about 1 year ago
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Answer A: What is the significance of push-pull and open drain controls in circuits?
A "normal" digital output actively drives both high and low. Open drain or open collector outputs only actively drive low, and go to high impedance when the signal is meant to be high. Some reasons the latter can be useful: Multiple outputs may be driving a bus. When devices only drive the bus ...
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about 1 year ago
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Comment Post #278066 @coq: I'm only looking at the circuit you posted as-is. I don't know what context or description might have come with it in any particular book, and that isn't relevant here anyway since you didn't specifically ask about that. Perhaps there is a flaw in my logic. If so, please point it out.
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about 1 year ago
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Answer A: Design rules for oamp bootstrap
That circuit doesn't do what you think it does. Here is the circuit in question: Image The impedance seen at IN is definitely higher at high frequencies, but that is only due to it being artificially low at DC. At DC, there is a load of 2R on IN, in parallel with the opamp input impedance. ...
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Answer A: Is there a mathematical process resembling the terms "digital"/"discrete" and "analog"/"continuous"?
I always had trouble understanding the terms "digital" and "analog" A digital signal is intended to indicate one of a finite set of discrete states. The number of discrete states is usually two for implementation simplicity. A two-valued digital signal is either high or low, on or off, etc. T...
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about 1 year ago
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Answer A: Antenna Feed Line Question
Any deviation from the example antenna could have significant and unintuitive consequences. Unless you have good antenna modeling software and good understanding of antenna physics (which you apparently don't since you're asking here), don't deviate from the suggested design. This includes the exac...
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about 1 year ago
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about 1 year ago
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Answer A: MAX809's Irregularity Depending on Load
Before we get into your problem, there are a few things to say about your descriptions. You need to step back and think about what we know and don't know, then learn to communicate specifications properly. That includes always making it clear what a number refers to, and using consistent names. ...
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about 1 year ago
Comment Post #277952 Too much unclear hand waving. Show a schematic. It is particularly confusing what all this buck converter is connected to, and how it relates to the MOSFET.
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about 1 year ago
Comment Post #277912 Seems reasonable, +1.
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Answer A: Doubt regarding loading.
A voltage source is "heavily loaded" when something is drawing a large amount of current from it. "Large" in this context is relative to what the voltage source can deliver, or perhaps relative to some normal or typical operation within a system. For example, it might be reasonable to say a 12 V ...
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about 1 year ago
Comment Post #277550 @aditya: C37 is not relevant to the question, and details about it would only distract and add confusion here. Ask a separate question if you want to get into that.
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about 1 year ago
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Comment Post #277845 *"on the output of a SMPS I recently bought because it was too high for the circuit I'm making"* What does it mean for an SMPS to be "too high"? Do you mean it's output voltage? Are you trying to lower the voltage with a filter? At first I thought you were trying to filter out ripple, but on clos...
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about 1 year ago
Comment Post #277845 Worked better than what? Show the other circuits, then it should be easy to explain why this one filters the ripple better. Also, tell us the ripple frequency you are trying to filter out.
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about 1 year ago
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Delete time wating fluff.
about 1 year ago
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about 1 year ago
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Answer A: Current Flow in the OFF Time of a Switching Power Supply
It's not clear whether you are asking about what the capacitor does in a buck converter, or how a capacitor works internally. I'll therefore go with: I am having a difficult time picturing the flow of current and the role of the capacitor during the OFF time of a buck converter. At this level,...
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about 1 year ago
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Article High/low indication of power supply with linear post-regulator
System description This concept provides a simple high/low indication for the output voltage of a power supply that is followed by an LDO (low drop-out) linear post-regulator. A basic diagram of the system is: Image The method presented here is particularly useful when the power supply is a...
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about 1 year ago
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Answer A: LED with a parallel resistor
You haven't provided any context, so there is little to say about this particular design. For all we know from what you told us, this could be homework from a student that just made a mistake. However, I have put resistors in parallel with LEDs in real professional designs. In all cases that I r...
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about 1 year ago
Comment Post #277547 What is the context? Where is this schematic from? How do you know it isn't just a bad design?
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about 1 year ago
Comment Post #277541 @Lundin: Right, but as I said, those are all in bank 15.
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about 1 year ago
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Answer A: How come the registers in a micro are application specific?
Calling those "registers" might be technically correct, but rather misleading in my opinion. These are really RAM locations. Probably for historical reasons, Microchip refers to RAM bytes in some of its microcontrollers as "registers" sometimes. Change "Complete Register List" to "Complete Varia...
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about 1 year ago
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Answer A: Why RC toys still operate in 27Mhz band?
Roughly around 27 MHz is the old "CB" (Citizen's Band, 11 meter) frequency block. The advantage of this band is that it is free to use with limited power. This is the band "walkie talkies" used to use. I remember back in the 1970s a bunch of us neighborhood kids had walkie talkies. You could si...
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about 1 year ago
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Answer A: 4-Layer PCB Routing Question
1 - Signal 2 - GND 3 - PWR 4 - Signal This seems to be common advice, especially on the 'net someplace, but that doesn't make it good. Stop and actually think about what problem you are trying to solve with each layer. What exactly do you think dedicating a whole plane to just power will do...
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about 1 year ago
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Deleted greeting. This isn't a kafeeklatsch.
about 1 year ago
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Answer A: Bypass Caps and High Frequency Current Return Path
First, let's be clear about something. All currents partially take all paths relative to the inverse of the path impedances. It's not an all or nothing function. This "Takes the path of least resistance" is often heard, but really not the best mental picture. For example, if a voltage is applie...
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about 1 year ago
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Answer A: Constant Current Load Circuit with Op Amp
Assuming nothing is broken or wired incorrectly, this is most likely the result of the opamp oscillating wildly. The average may still be about what it should be, so you might not notice with only a meter. Put a scope on G and S of Q1. Oscillation should be no surprise, since it's quite possible...
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about 1 year ago
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Answer A: Darlington or Sziklai configuration - why and when using complementary pairs?
Why do the Darlington or Sziklai configurations need complementary transistors? They don't. In fact, it's usually not even desirable. However, before we get too far, let's make it clear what we are talking about: Image In this example, both constructs result in overall NPN polarity. I'l...
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about 1 year ago
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Answer A: Complementary transistor pairs - what is the point ?
You generally want complementary NPN/PNP pairs when they are used as opposites of each other in the same circuit. One transistor is usually used with opposite polarity as a mirror image of the other. For example, consider this circuit: Image Q1 drives the output during the positive half of ...
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about 1 year ago
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Answer A: Amplifier compensation with added resistor across opamp input terminals
Here is the circuit in question, with the component designators changed to make them easier to write: Image To understand this circuit, try building it up in pieces. First, let's only include R1 and R2. The circuit is then a basic non-inverting amplifier with a gain of (R1 + R2)/R2. Now ...
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about 1 year ago
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Comment Post #276117 @tim: You should ask that as a real question.
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about 1 year ago
Comment Post #277048 @coq: I misunderstood your R2. I thought you were trying to model the leakage due to the broken insulation.
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Answer A: How could a damaged wire in split-phase power delivery create these voltages?
Here is a basic diagram of the power feed to your house, according to what the power company said they found: Image R1 represents the additional series resistance due to the cable being corroded. R2 represents the leakage current to ground due to the broken insulation. Both these can vary ove...
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about 1 year ago
Comment Post #277032 @coq: I'm an opamp kind of EE, not electrical power engineering. I do have an explanation that I think makes sense, but I was hoping one of the electrical power folks would jump in. I just got to a good break point in my day job work, so maybe I'll post my idea soon.
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about 1 year ago
Comment Post #277032 I think this is a good start, +1, but I disagree that the leakage is to L1, not ground. I think there is more to it than you show.
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Put image directly into question. Next time you do that.
about 1 year ago
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Answer A: Should I connect signal reference and chassis ground in a battery powered application?
It's not totally clear from just the verbal description, but it seems the real question is when/if signal and chassis ground should be connected. If the circuit is not intended to be truly isolated, then signal and chassis ground need to be connected at some point. The trick is to think about all...
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about 1 year ago
Comment Post #276952 Show a diagram. I got lost in some of the hand waving.
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about 1 year ago
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Answer A: Substituting multiple lower voltage resistors for a high voltage resistor.
Yes, this is safe, but you do have to consider the layout carefully. You have to make sure that nothing conductive gets between the pads of each resistor. For this high voltage safety purpose, you can't consider the solder mask as a reliable insulator. If a trace goes between the pads of a resis...
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about 1 year ago
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Answer A: Is it possible to use two zener diodes in series back to back to replace a diac?
It's not clear what you are really trying to do, but if you're trying to replace the left circuit with the right one, that's a bad idea: The left circuit switches to appear to pass partial voltage. That means it doesn't dissipate much power. Power into something is the voltage across it time...
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about 1 year ago
Comment Post #276809 @Andy: You should be a mod here anyway (even though this has nothing to do with this particular question). You are one of the original core group that proposed this site. I don't know how to make it happen. Perhaps the admins don't realize you were one of the original core.
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over 1 year ago
Comment Post #276809 I just checked, and there seems to be nothing in the mod tools to look at voting patterns at all. It would be nice if each of us could see recent rep changes, like there was on SE. I asked for that at https://meta.codidact.com/questions/276332, but was largely ignored, or it got used to malign rep ...
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over 1 year ago
Comment Post #276763 I added the short description for the Papers category to the end of my question. This may change if there is consensus to do so, but we have to start somewhere.
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Comment Post #276763 Thanks. Now I need to get busy adding some help pages. If only the day job would leave me alone for a while ...
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over 1 year ago
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Comment Post #276736 @mana: Collaboration on a paper makes sense, but we would need some new features from the system for that to work. We would need the concept of multiple authors, and a way to have drafts that only the authors can see until the paper is published. We don't want all the noise of multiple people event...
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over 1 year ago
Comment Post #276736 Nobody is going to get punished for writing a bad paper, unless it's clearly spam or the like. Well intentioned but bad papers will merely get downvoted to oblivion. If the author feels that is punishment, he can always just delete the paper and it never happened. That said, papers will be held to...
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Answer A: What is the added value - still unclear
This site grew out of frustration with how SE was managing their sites, seemed to value clicks over quality, and lost appreciation for those providing the content that the clicks came to get. This site is not run by a for-profit corporation. There is no danger that investors will get restless and...
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over 1 year ago
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Answer A: How do I calculate and manipulate the inductance and capacitance of outputs to a connector on a PCB?
It's not completely clear, but it seems you are asking about a circuit in a class 1 div 2 location that will drive another circuit in a class 1 div 1 location. The point of the IS barrier is to present a Thevenin source. In other words, the two important criteria are the open circuit voltage and ...
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over 1 year ago
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Comment Post #276602 Response added to question.
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Answer A: Digital circuit that squares a 4-bit input
No, I have not seen this circuit before, and don't know what source you may have gotten it from. However, I'm not sure that really matters. I don't know what exactly you are trying to teach, but most likely the derivation of the circuit is the real lesson. The actual circuit is of little use, an...
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over 1 year ago
Comment Post #276235 @Monica: Consider yourself pinged.
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over 1 year ago
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Comment Post #276570 @mana: I see you made a suggested edit, but I can't figure out what it is. I click on Review Changes, and I get two texts side by side that look the same as far as I can tell. If there is a change, the system should highlight it somehow. I don't want to approve something when I can't tell what I'm...
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over 1 year ago
Comment Post #276570 @mana: But that's a bad idea some sites. I realize some don't like rep. That's fine. But they also don't want anyone else to have it on other sites where it would help. That's not fine. There needs to be a single obvious "score" somehow that shows how much a user's contributions were appreciated...
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Question Let's have a "Papers" category.
Currently, we have two categories, Q&A and Meta. Those seem to be working well. New topic type available A category can now be created where there is a single post per topic, with only comments allowed on that post. The Meta site uses this for their Blog category, and the Cooking site for the...
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over 1 year ago
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over 1 year ago
Comment Post #276408 @Brok: Your schematic shows a normal diode. You need to take more care with your schematics. You are wasting the time of the volunteers that are trying to help you.
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Answer A: Humming noise from a boost converter's inductor
First, draw schematics properly when you ask others to look at them. Your right to left flow is rather annoying. There are two main possibilities for this circuit to cause noise, the inductor and the output capacitor. Inductor The inductor can make sound for two reasons: Every bit of wir...
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over 1 year ago
Comment Post #276378 What Lundin said, since we can't upvote comments here.
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over 1 year ago
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Answer A: Switch-off time of relay with flyback diode
It doesn't quite work that way. You are missing the fact that the current (which the magnetic field is proportional to) decays exponentially. You are also missing the resistance of the coil itself. First, let's analyze what happens with just a diode. You basically have this circuit: Image al...
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over 1 year ago
Comment Post #276117 @Chup: That depends on the relay. For some "fast" relays, it might make a difference. For relays that take 10s of ms to switch, it probably wouldn't matter anyway. You really have to check the datasheet or ask the manufacturer if switching speed is not specified.
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over 1 year ago
Comment Post #276294 @Lundin: The compiler can't make that assumption simply due to the variable being global.
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Answer A: When to use RTOS?
RTOS A RTOS (Real Time Operating System) is much more than a bunch of interrupts. Most true dedicated microcontroller applications don't need any RTOS or any other kind of operating system. General OS (operating system) An OS adds a layer of abstraction between your application and the hard...
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Answer A: What is a bootloader, and how would I develop one?
Bootloader definition A bootloader is a program that runs in the microcontroller to be programmed. It receives new program information externally via some communication means, like a serial port, and writes the information to the program memory of the processor. This means that bootloaders ca...
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over 1 year ago
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Question What is a bootloader, and how would I develop one?
I've heard that a bootloader is code that runs on a microcontroller, and is used to get your application code onto the micro. How does that work? Is there anything special that needs to be done to write a bootloader? If a bootloader is for getting code onto a micro, how do you get the bootloa...
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over 1 year ago
Comment Post #276294 Nice writeup with lots of detail, +1. However, all hardware registers don't need to be declared volatile, only the ones the hardware can change. For example, a UART baud rate divider register would not need to be volatile, since you write the value and the hardware never changes it.
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over 1 year ago
Comment Post #276263 @Andy: I changed the TIFF image to JPEG. Can you see it now?
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Comment Post #276263 @Andy: See the main meta question https://meta.codidact.com/questions/276272 and let them know which images you see.
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over 1 year ago
Comment Post #276263 @Andy: Strange. I see it in my browser. I'm using Edge on Win 10, and also just tested it with IE on Win 10. Both showed the image correctly. What browser and OS are you using?
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over 1 year ago
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Answer A: Low loss impedance matching without a transformer
As an alternative to doing the math, as detailed in Andy's answer, you can use a graphical aid called a Smith chart: Image alt text These were used routinely before computers to match transmitters to antennas. The math behind them is what Andy described. See the Wikipedia page for details, wh...
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over 1 year ago
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Answer A: Chokes, Beads and Inductors in Pi-filters
Pi filters are often used to block high frequencies between a device and the power line it draws power from. In such applications, the considerations specifying the inductor include: How much power current needs to pass, preferably unimpeded by the filter. What frequencies need to be attenuate...
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over 1 year ago
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Answer A: Pi-Filter for EMC
First let's define what a "Pi filter" is: Image alt text The name comes from the inductor and two caps forming the shape of the Greek letter &Pi;. These filters are used for EMC compliance because they attenuate high frequencies. At minimum there is a L-C filter, which attenuates by 12 dB/o...
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over 1 year ago
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Answer A: Tools required to burn code in a quad flat microcontroller
The days of socketed microcontrollers are long gone. In most cases, the socket would cost more than the micro. Nowadays, microcontrollers, whether in quad flat pack packages or not, are surface mount soldered onto boards along with all the other parts. There are then two ways to get the program ...
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over 1 year ago
Comment Post #276217 @Bruce: I don't know what to tell you. The URL is the one Codidact produced when I uploaded the image. I can see the image in both the Edge and IE browsers. If you are using a modern supported browser, then maybe you should report this as a bug on main meta.
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Comment Post #276235 @mana: I'm going to wait a day or two to give others a chance to chime in. If nobody does, we'll go with the above.
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over 1 year ago
Comment Post #276225 At these voltages, you really should consider a Schottky diode. Half the forward drop would make a difference here, and they are fast too. The higher reverse leakage is not much of an issue in this application. However, +1 anyway :-)
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over 1 year ago
Comment Post #276235 @mana: I hadn't thought of that alternate interpretation. I would like to mention the electronic part first, since that is the overwhelming majority of the questions. I could go with "... electronic systems, electric power systems, their theory …". Would that be acceptable?
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Answer A: Tagline/Mission Statement/etc.
The short phrase is trying to capture the two broad classes of topics here: Electronic things, like opamps, transistors, microcontrollers, 20 W power supplies, and the like. Utility-scale power systems, like multi-MW generators, large over-land transmission lines, local distribution systems of ...
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Answer A: Moving average that uses less memory?
You can't eliminate all noise, use no memory, no processing cycles, and not add some lag. However, you can do much better than a brute force "moving average" filter. FIR versus IIR filters There are two broad classes of digital filters, FIR (finite impulse response), and IIR (inifinite impu...
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Question Moving average that uses less memory?
My control system gets a signal representing the plant output, but that signal has a lot of noise on it. The control system goes nuts trying to react to the noise. I need to filter out the noise somehow, but preserve the basic plant response. I heard about a moving average and tried it. It hel...
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over 1 year ago
Comment Post #276160 @manass: Markdown is simpler, but that simplicity comes at the cost of ambiguity and too many unintended markups. I also don't want to have to remember two syntaxes. Use markup if you like, but please make sure all the same formatting features continue to be available via some subset of HTML. Actu...
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over 1 year ago
Comment Post #276166 @Andy: I was only saying that the issues you bring up are not unique to this EE site. They apply to the Codidact software in general. I didn't pass any judgement about what is a bug, what's not, and what is a feature. I was also trying to make it clear that this software is work in progress. Work...
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over 1 year ago
Comment Post #276166 Most of these are system-wide issues, not specific to this EE site. There is a system-wide meta for that, but the people that would see that might also notice it here. The software is very much still in development, but far enough along to have at least basically working Q&A sites. I was really as...
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over 1 year ago
Comment Post #276146 @Lundin: Some of what you ask for already existed. I also just added a few items. Repair questions are tricky to make on-topic. There should probably be a help page devoted to them, like there is for component ID questions. I'll work on that as I have time.
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Comment Post #276146 @Monica: Thanks, but I think we'll wait a bit on that. Creating lots of categories early makes the site look even more empty than with the single category we have now. We may eventually get there. Time will also help us see where splits make the most sense. Frankly, I think it was a mistake of Ph...
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Answer A: Viewing the potential live output when editing a question or answer.
I recommend using native HTML for lists, and most other formatting for that matter. HTML gets around the ambiguity of what is an item and what is text following the list. The list isn't over until the &lt;/ol&gt; tag. For more information about formatting, see the Formatting Posts document in th...
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Answer A: Driving LED with NPN transistor from I/O pin
First, let's redraw the circuit a little more clearly, with logical flow left to right. This also protects the answer from possible changes to the question. Image alt text As you say, Q1 is a switch to control the LED. Most likely, a separate transistor was used to keep the LED current out of...
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over 1 year ago
Edit Post #276137 Initial revision over 1 year ago
Answer A: How to calculate pullup resistor value for pushbutton?
To understand this issue, we have to look at how your circuit works and what the pullup does within it. You have a pushbutton you want to read with a microcontroller. The pushbutton is a momentary SPST (Single Pole Single Throw) switch. It has two connection points which are either connected ...
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Edit Post #276136 Initial revision over 1 year ago
Question How to calculate pullup resistor value for pushbutton?
What value pullup resistor should I use for a pushbutton connected to a microcontroller input? Image alt text I've seen values from 1 k&Omega; to over 100 k&Omega;. Some references just say to use 10 k&Omega; because it's a "good value". How do I calculate this to decide for myself?
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Edit Post #276117 Initial revision over 1 year ago
Answer A: Driving relay, transistor keeps failing
The reason the transistor is dying is because you didn't put a flyback diode across the relay coil. Relay coils have significant inductance. This means the current can't change instantly without the voltage being infinite. It takes voltage applied over time to change the current thru an ind...
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Edit Post #276116 Initial revision over 1 year ago
Question Driving relay, transistor keeps failing
I'm trying to drive a relay according to a 5 V digital signal, using this circuit: Image alt text It works for a while, but then the transistor fails. When I replace the transistor, it works for a while again, then fails again. The transistor is rated for 600 mA and 40 V. I'm only running 63...
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Comment Post #276106 @aCVn: Good point about AC versus DC. I added a section for that.
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Answer A: Replacement power supply voltage and current ratings?
Voltage Rating If a device says it needs a particular voltage, then you have to assume it needs that voltage. Both lower and higher could be bad. When no tolerance or input voltage range is specified, &plusmn;5% should be close enough. &plusmn;10% will probably be OK most of the time. I wo...
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Edit Post #276105 Initial revision over 1 year ago
Question Replacement power supply voltage and current ratings?
If the external power supply to a device fails, and I can't get the exact model, what do I need to specify to get the right replacement? I can re-use the old supply's connector, but what about the voltage and current ratings? How close do they need to be to what it says on the device? What i...
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Comment Post #275960 @Monica: Yes, I plan on adding a few canonical questions. I've been busy with the help pages, and the day job gets in the way too. Do you think this is something we need to do before getting the word out about the site?
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Question Are we there yet?
Are we ready to let the world know about this site yet? What, if anything, do we still need to do or set up first? I have created a bunch of help pages that are intended to give newcomers a good idea how to use the site, and what is expected of them. There is an infinite amount of information th...
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Comment Post #275874 @Monica: I'd like a link to https://electrical.codidact.com/help/intro with something like "Read this before posting" from the main Q&A page. Maybe the "this" is the clickable link? You can decide the details, but there should be no excuse for not having known that page should have been read before...
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Comment Post #275888 @Monica: Maybe a fourth posting tip that links to https://electrical.codidact.com/help/asking "for more detail" or something like that?
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Comment Post #275874 @Monica: I think the short text is good. That's not the place for a detailed list like this.
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Comment Post #275888 Yes, I'm working on documentation about the site. Even though the site framework has been set up, I don't consider it ready yet. This is mostly about lacking documentation. You can see where I started this with "Intro to this site" under HELP. I don't want to advertise the site until all this is ...
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