Activity for Olin Lathrop‭

Type	On...	Excerpt	Status	Date
Answer	—	A: Effect of adding stages to a filter There are a number of misconceptions here. bode plot db/Hz First, it's "dB", not "db". Second that's not a Bode plot. Those are dB/Log(Hz). In other words, a certain frequency ratio results in a fixed gain ratio as the slope approaches the asymptote. You were told in your previous questio... (more)	—	almost 2 years ago
Answer	—	A: How to design a low-pass filter when certain conditions must be met Simple filters don't cause a fixed ratio change in amplitude (dB) for a fixed change in linear frequency (Hz). Making the amplitude change by -0.1 dB/Hz would be very difficult. This could be done with a very carefully designed digital filter. However, there is a loophole. Since only the averag... (more)	—	almost 2 years ago
Answer	—	A: Siglent1104 oscilloscope channels lagging If all four channels are really connected to the same signal in the pictures you show, then there is indeed some skew between pairs of channels. Try swapping probes to see if the lag goes with the probe or the channel. Also try on the 1x setting. That should have less parasitic low pass filter... (more)	—	almost 2 years ago
Answer	—	A: Limiting current to DC brushed motor I don't think there is a simple way to inherently limit the current to 10 A. The best approach seems to me to add a low side current sensor between the bottom of the H bridge and ground. The main tradeoff is getting enough current resolution without excessive voltage drop or power dissipation. ... (more)	—	almost 2 years ago
Answer	—	A: H-Bridge components and calculations Firstly, is this calculation for power dissipation correct? P = (I2 R) + (I V (ton+toff)/2 f) = 0.517 W Not completely. There are two separate parts that need to be considered. I2RDSON is the power dissipated by the FET when on. However, you can't use the average current. You have to av... (more)	—	almost 2 years ago
Answer	—	A: Mysterious little cases hanging on street wirings in India This is not a direct answer, but a few observations that might be clues. The additional pictures help, but you still haven't answered where this is. The purpose of the question was to get some idea of how formally things are done in your area. This pictures show a mess, hinting at this being s... (more)	—	almost 2 years ago
Answer	—	A: What effect will extreme temperatures have on characteristic impedance of a wire? The expansion of the conductors is the least of your problems. The real issue is the effect of excessive temperature on the insulators. The plastic in the cable has three electrical functions: To insulate the two separate conductors. To provide a specific constant dielectric between the con... (more)	—	almost 2 years ago
Answer	—	A: Unexpected impedance spike when paralleling capacitors Unfortunately the frequency legend on your graphs are too small to see, so we don't know how the left and right graphs relate to each other. However, what is certainly going on in the left graph is a LC resonance. Again, it would be useful to know where that peak is in relation to the right graph... (more)	—	almost 2 years ago
Answer	—	A: Re model of transistor is the same in 2 different configuration I'm not sure what you mean by the "Re" model, but ultimately the transistor does a certain thing regardless of what label we put on the circuit it is in. For a NPN like you're modeling, you will have base current going into the base and coming out the emitter, and collector current going into the ... (more)	—	almost 2 years ago
Answer	—	A: Thévenins Theorem for Transistor Circuit It seems like you did the reduction to a Thevenin source mostly right, although the final value is a bit off. The original circuit we want to reduce to a Thevenin source is: First we reduce V1, R1, and R2 to a Thevenin source. The resistance is R1//R2, and the voltage is the V1 voltage app... (more)	—	almost 2 years ago
Answer	—	A: Wish to have comment votes I see that Monica answered your question directly. However, there is another point to keep in mind. Comments are not for content. That was supposedly the case at SE too, but was poorly enforced. We are more strict about that here. Comments therefore shouldn't be important enough to vote on. ... (more)	—	almost 2 years ago
Answer	—	A: How do PLCs normally measure 4-20mA current loops? You should not be relying on the internal circuitry of whatever senses the 4-20 mA current. Note that the two implementations you show both use current sense resistors. The only difference is their value. I have designed several current-sense front ends, although none were inside a PLC. The cus... (more)	—	about 2 years ago
Answer	—	A: Level shifting of a 3 state logic pin No, a resistor divider is not appropriate, at least not if you want to get all the information from the STAT pin. In addition, that chart in the datasheet is incomplete at best, or downright misleading if you're less charitable. The first problem is that a single signal indicates three possible v... (more)	—	about 2 years ago
Answer	—	A: When do I need to put anti-aliasing filter in front of SAR ADC? Since your noise has "unknown characteristics", you should do low pass filtering in analog before the discrete sampling of the A/D. The two parameters that matter are the frequency content of the signal, and the sampling rate. In theory, nothing is lost as long as the sample rate is more than twi... (more)	—	about 2 years ago
Answer	—	A: Misuse of mod privilege? It seems your main question is why all the comments to your question about reactance were deleted. I deleted them because they were no longer relevant. They pointed out problems with the question, and explained why it was closed. You then fixed the question, it was reopened, and it has now gotten ... (more)	—	about 2 years ago
Answer	—	A: Oscilloscope potentially ESD striked If you're really sure the symptom appeared right after the static discharge, then something in the front end of the amplifier may have gotten damaged. However, that sounds rather far fetched. Scopes should have protection against these kind of events. Were all the effected channels connected to so... (more)	—	about 2 years ago
Answer	—	A: Duty cycle of buck-boost converter Nevermind (for now) what Wikipedia or anyone else says. Stop and actually think about it. One problem with the question is that is says "buck-boost" but doesn't otherwise define that. A buck-boost converter generally means that the output can be both above or below the input. There are differen... (more)	—	about 2 years ago
Answer	—	A: DAC controlled high side current source. It appears you want a positive current source with the following specs: 0 to 28 V compliance range. Up to 100 mA, adjustable via 10 bit or more digital value. 36 V supply is available. The dissipation from a linear pass element is OK. The large headroom at the high end allows for e... (more)	—	about 2 years ago
Answer	—	A: Case temperature of MOSFET Yes, you seem to understand the concept. From the case to the ambient air, there will be 1.3°C per watt across the pad, and another 2.0°C per watt across the heatsink. In total, there will be 3.3°C per watt from case to ambient air. Since the part is dissipating 10 W, the case will b... (more)	—	about 2 years ago
Answer	—	A: How to choose the right value for input voltage ripple of an SMPS? There are two issues with input voltage ripple: The input voltage being too high or low for correct operation, and high frequency noise on the input. The first is pretty straight forward. You make sure that the nominal voltage ± the peak ripple is never above or below the guaranteed operat... (more)	—	about 2 years ago
Answer	—	A: PCB ground planes with isolated voltage Your description is confusing due to lots of hand waving, so it is hard to be specific. However, an isolated section should be separated from the non-isolated parts laterally. It depends on the exact spec or certification you are going after, but usually 5 mm is good. It can be more than that, lik... (more)	—	about 2 years ago
Answer	—	A: Press fit PCB receptacle for plated holes (Marked for non-plated holes) Considering that the same manufacturer has models specifically for plated holes too, it probably matters. One thing that I noticed in looking around is that the models for unplated holes have a knurled collar, whereas the ones for plated were hexagonal there. My guess is that the knurling is me... (more)	—	about 2 years ago
Answer	—	A: Why are there more N type than P type MOSFETs? There are two predominant reasons you see N channel FETs more than P channel: N channel is the natural polarity for ground-referenced switches controlling loads with positive voltages. This is convenient because most controlling circuitry is ground-referenced too, with positive supply. With th... (more)	—	about 2 years ago
Question	—	Let's make all downvotes public One of the aggrevations Elsewhere were all the vandal and retribution downvotes. They never took the problem seriously. Now it's happening here. Andy was the latest target, twice, recently. I've also had this happen to me on other Codidact sites, like Outdoors. All downvotes should be public ... (more)	—	about 2 years ago
Answer	—	A: Creating an "Insights" category We have such low volume as it is, that I wouldn't want to see another category added at this time. It would only emphasize how little traffic there is. Let's not make the same mistake that Photography made. They have lots of mostly-empty categories. Some day when there is enough content, I co... (more)	—	about 2 years ago
Answer	—	A: Creating an "Insights" category What you describe is already allowed in Papers. See electrical.codidact.com/help/papers. The papers by Circuit Fantasist are well on topic. Presenting a concept in an accessible way is OK. I haven't upvoted most of those papers either, but that's because I think his teaching style, and particul... (more)	—	about 2 years ago
Answer	—	A: Flyback transformer for Vout > Vin A higher voltage can be produced at 1:1 ratio because the transformer is being run in flyback mode. Unlike normal forward mode, the primary and secondary don't conduct at the same time. The input pulse builds up current in the primary. This does produce the same voltage on the secondary. Howeve... (more)	—	about 2 years ago
Answer	—	A: What reactance actually is? Your third equation defines impedance. Rearranged to solve for Z, it is:     Z = V / I Note that this is exactly Ohms law when V and I are real numbers. In the general case of impedance, all three values can be complex numbers. Put another way, impedance is more generalized resista... (more)	—	about 2 years ago
Answer	—	A: PNP Darlington pair as a current limiter Follow the current. Q3 is a controlled current sink. Whatever voltage is applied to its base appears across R11 minus the B-E drop. That voltage on R11 causes a particular current to flow. That current obviously flows out of the emitter of Q3. Due to the transistor's gain, most of that comes f... (more)	—	over 2 years ago
Answer	—	A: H(jω) does not exist for unstable systems, but we still use it when designing controllers - contradiction? I think this is partly semantics. For example, consider designing a compensator for a power supply. The transfer function under consideration is essentially the open loop impulse response of the system. If that goes nuts, then you have other problems to fix first. You are right in that it needs... (more)	—	over 2 years ago
Answer	—	A: Creating a FAQ: how to read a datasheet I think this would make a good Paper. I know you want others to collaborate, but that's something that doesn't really work. "Community Wiki" certainly never worked right on SE. Too many cooks make a mess, no matter how good each cook is. Go ahead and write a paper. If the result is good, I'l... (more)	—	over 2 years ago
Answer	—	A: How to protect RF switches from ESD? Those are good questions, and I don't have a single definitive answer for them. I'd start with putting an appropriate TVS (or maybe separate diodes to ground and 3.3 V) between C3 and S1. My reason for clipping there is because then this gets to work against the impedance of the inductor. Look c... (more)	—	over 2 years ago
Answer	—	A: How to calculate the RC filter of a TCXO for a RFIC reference? The RFIC manufacturer recommends to "add filtering caps" for high RF output cases. It seems your questions are really about this RF IC, not the oscillator. The oscillator itself seems to be pretty straight forward. You apply power and an accurate frequency comes out, which is 30 MHz in your case... (more)	—	over 2 years ago
Answer	—	A: Choosing Y value in photoresistor graph If you truly have a photoresistor, then resistance as a function of brightness makes more sense. It's the resistance that is roughly constant for a fixed brightness as voltage is varied. Put another way, the current is roughly proportional to voltage at any one brightness. However, if you actual... (more)	—	over 2 years ago
Answer	—	A: Electromagnetic induction You are asking about this circuit and want to know whether this is a radio transmitter/receiver system. No, it's not. First, everything is DC. There is no radio propagation at DC (0 frequency). Second, although the question mentions antennas, there are none in this circuit. Radio tr... (more)	—	over 2 years ago
Answer	—	A: Standardized schematic/layout file formats for PCB CAD tools? As far as I know, there is no standard format, at least not one supported by many packages. What I would look for instead is the existence of converters. Check the ability of a tool to export or import in another's format. Then ask around and look at reviews to find the quality of these converte... (more)	—	over 2 years ago
Answer	—	A: How do I design a flyback converter? What are the basics I should know? I see Andy has already given a detailed answer with a lot of good background on flyback converters. I'll answer the question more directly about how I would step thru this design if given these requirements. For reference, here is the general flyback converter circuit copied from the question:... (more)	—	over 2 years ago
Answer	—	A: PCB Copper Layer Spacing & Voltage Rating I am not familiar with that standard specifically. However, usually standards will have some multiple for effective separation distance inside a PCB versus across air. One standard I remember specifically states that PCB material is worth 6x the distance relative to air. This method gets around ... (more)	—	over 2 years ago
Answer	—	A: Design considerations for a differential pair As far as I know from my own experience, CAN and at least 10 Mbit twisted pair ethernet both care about the impedance between the two wires, not so much from each wire to some common ground. This is quite obvious for ethernet since the twisted pair drives a transformer. There is no third conducto... (more)	—	over 2 years ago
Answer	—	A: Via on pad: acceptable or not? This can be OK if you consider and address the consequences carefully. It's something I would only do as a last resort. Usually I try to make sure the hole itself is outside the outline of the pad, and therefore covered with soldermask. The major problem I see is the via making a thermal connect... (more)	—	over 2 years ago
Answer	—	A: Bandwidth of serial signal You have to decide what you really mean by "bandwidth". The analog bandwidth of the channel is quite different from the bit rate, which is different from the effective bit rate of the actual transferred data. Let's take the common UART protocol of 9600 8-N-1 (9600 baud, 8 data bits, no parity, on... (more)	—	over 2 years ago
Question	—	Flyback transformer with Intrinsic Safety I have no experience designing for Intrinsic Safety (IS), but need to do that now. I have read thru IEC 60079-11, which seems to be the relevant standard for my purposes. The board I need to design will be an "associated apparatus" in IS terms. That means the board won't be in a hazardous locati... (more)	—	over 2 years ago
Answer	—	A: How to treat data communication questions? I agree that the particular question was correctly closed. Questions about protocol stacks aren't necessarily off topic. However, this one was because nothing about it had anything to do with electronics or low level embedded systems. Where should I ask it then? I don't know. That's not ... (more)	—	over 2 years ago
Answer	—	A: How can we grow this community? Another thing that would be helpful is to get the existing users to participate more. Upvote good questions when you see them! For example, the question "208VAC triple-phase to single-phase conversion" was posted 2 days ago. It is on topic, well asked, well written, and appears to be a genuine... (more)	—	over 2 years ago
Answer	—	A: Do we need tags for supply voltages? I agree that "208VAC" and "230VAC" are too specific to be useful. I tried to edit the post to remove them. There is apparently a bug in the system. While I removed both tags from the post, one of them still shows. However, when I go to edit the post again, that tag is not there, so I can't remo... (more)	—	over 2 years ago
Answer	—	A: 208VAC triple-phase to single-phase conversion You need a real transformer that converts 208 V to 230 V, so a ratio of 1:1.11. This can not be an auto-transformer because you need isolation between the primary and secondary. That is because you will ground one side of the output, but neither input can be connected to ground. Alternatively, y... (more)	—	over 2 years ago
Answer	—	A: How can we grow this community? One way we can grow this community is to have existing users here mention the site at relevant gatherings. Unfortunately, those have been non-existent or virtual due to covid. Passing on a recommendation about a Q&A site is the kind of side-conversation that doesn't happen as much in virtual meetin... (more)	—	over 2 years ago
Answer	—	A: Asynchronous connection question How does the receiver understand the end bits? It doesn't. The purpose of stop bits (what you seem to be calling "end bits") is to leave a guaranteed gap before the next start bit. The leading edges of start bits are always idle to non-idle transitions. The line must therefore always be at id... (more)	—	over 2 years ago
Answer	—	A: How long does it take for energy to propagate in a circuit? Is the answer of 1/c seconds correct It can't possibly be. The question is looking for a time value. "C" is a speed, which has units of distance/time. "1/c" therefore has units of time/distance. In this case, 1 is 1 meter "1" is never one meter. "1 m" or "1 meter" is one meter. Ad... (more)	—	over 2 years ago
Answer	—	A: Flyback converter design i dont know how to control two outputs with a single control loop Neither does anyone else. Your output has two degrees of freedom, and your control input only one. That's a fundamental problem you can't fix with any amount of clever design. Physics can be annoying like that. However, you ca... (more)	—	over 2 years ago

• ← Previous
• 1
• 2
• 3
• 4
• 5
• 6
• 7
• Next →