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Activity for Olin Lathrop‭

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Edit Post #279535 Post edited:
about 6 hours ago
Edit Post #275889 Post edited about 8 hours ago
Edit Post #279535 Post edited:
about 8 hours ago
Edit Post #279535 Initial revision 1 day ago
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.     Out =...
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1 day ago
Edit Post #279484 Post edited:
Removed fluff. To thank people, upvote answer if you think they are good.
4 days ago
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4 days 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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4 days ago
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4 days 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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4 days 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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6 days 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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6 days 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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7 days ago
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7 days ago
Edit Post #279405 Initial revision 8 days ago
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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8 days ago
Edit Post #279285 Initial revision 11 days 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 days 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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12 days 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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12 days 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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16 days ago
Edit Post #279104 Initial revision 16 days 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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16 days ago
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17 days ago
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17 days ago
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19 days ago
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20 days ago
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20 days 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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20 days 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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20 days 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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20 days ago
Comment Post #279010 @Circ: No, what he "invented" was just a comparator with a lot more parts than necessary.
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20 days ago
Edit Post #279010 Initial revision 21 days 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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21 days ago
Comment Post #278989 What "TVS diode"? I don't see a TVS anywhere in that schematic.
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22 days 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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22 days ago
Edit Post #278986 Initial revision 22 days ago
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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22 days 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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26 days ago
Edit Post #278898 Initial revision 29 days ago
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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29 days ago
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about 1 month ago
Edit Post #278856 Initial revision about 1 month ago
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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about 1 month 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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about 1 month 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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about 1 month ago
Edit Post #278823 Initial revision about 1 month ago
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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about 1 month ago
Edit Post #278820 Initial revision about 1 month ago
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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about 1 month 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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about 1 month 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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about 1 month 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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about 1 month 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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about 1 month 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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about 1 month ago
Edit Post #278760 Question closed about 1 month 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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about 1 month 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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about 1 month ago
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about 1 month 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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about 1 month 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 kΩ ±5% resistors in series is a 2 kΩ ±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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about 1 month ago
Edit Post #278717 Initial revision about 1 month ago
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 kΩ 5% by putting two 1 kΩ 5% resistors in series? Or are two 4 kΩ 5% resistors in parallel better? Is there some way to use mul...
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about 1 month 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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about 1 month 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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about 1 month ago
Comment Post #278703 I don't think it's worthy of a downvote, so have an upvote from me.
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about 1 month ago
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about 1 month ago
Edit Post #278704 Initial revision about 1 month ago
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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about 1 month 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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about 1 month ago
Edit Post #278669 Initial revision about 1 month 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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about 1 month 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 month ago
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about 1 month ago
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 month 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 month 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 month ago
Edit Post #278601 Initial revision about 1 month ago
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 month 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 month 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 month 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 month 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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about 1 month ago
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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 month ago
Edit Post #278522 Question closed about 2 months ago
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about 2 months ago
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about 2 months ago
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 2 months ago
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about 2 months 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 2 months 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 2 months ago
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Fixed to make on-topic
about 2 months ago
Edit Post #278477 Initial revision about 2 months ago
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 2 months 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 2 months ago
Edit Post #278462 Initial revision about 2 months ago
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 2 months ago
Edit Post #278449 Initial revision about 2 months ago
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 2 months 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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about 2 months ago
Edit Post #278421 Initial revision about 2 months ago
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 2 months 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 2 months ago
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Removed pointless fluff.
about 2 months 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 MΩ and 100 nF part values you cite.
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about 2 months 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 2 months ago
Edit Post #278346 Initial revision about 2 months ago
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 2 months 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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2 months 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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2 months ago
Edit Post #278213 Initial revision 2 months ago
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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2 months 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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2 months 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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2 months 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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2 months 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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2 months ago
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2 months 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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2 months ago
Edit Post #278079 Initial revision 2 months ago
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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2 months ago
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3 months ago
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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3 months ago
Edit Post #278066 Initial revision 3 months ago
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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3 months ago
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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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3 months ago
Edit Post #278001 Initial revision 3 months ago
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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3 months ago
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3 months 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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3 months 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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3 months 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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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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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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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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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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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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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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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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Comment Post #277541 @Lundin: Right, but as I said, those are all in bank 15.
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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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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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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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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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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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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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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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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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Comment Post #276117 @tim: You should ask that as a real question.
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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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4 months 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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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.
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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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Comment Post #276952 Show a diagram. I got lost in some of the hand waving.
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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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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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4 months 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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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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4 months 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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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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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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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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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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Comment Post #276235 @Monica: Consider yourself pinged.
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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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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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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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Comment Post #276378 What Lundin said, since we can't upvote comments here.
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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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5 months 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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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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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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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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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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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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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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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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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 Π. 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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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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5 months 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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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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5 months 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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5 months 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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5 months 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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5 months 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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5 months 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 </ol> 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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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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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 kΩ to over 100 kΩ. Some references just say to use 10 kΩ because it's a "good value". How do I calculate this to decide for myself?
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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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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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6 months ago
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, ±5% should be close enough. ±10% will probably be OK most of the time. I wo...
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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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6 months ago
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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