Activity for Olin Lathropâ€
| Type | On... | Excerpt | Status | Date |
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| Edit | Post #288971 | Initial revision | — | almost 2 years ago |
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A: Is there an easy way to measure the characteristic impedance of a cable using basic lab instruments? What you basically ask for can be done (I've done it), but not all your specific constraints can be reasonably met. The way to measure transmission line impedance is to drive a step onto the transmission line with a known resistance, while observing the waveform on a scope. During the time the st... (more) |
— | almost 2 years ago |
| Edit | Post #288923 | Initial revision | — | almost 2 years ago |
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A: Are a JFET's Idss and Vgs(off) values correlated? I'll let someone else answer about the device physics. I'll answer from an electrical engineering standpoint. The answer is: Maybe, but it doesn't matter since you should be considering worst case in your design anyway. You are really asking whether there is any correlation between the gate vo... (more) |
— | almost 2 years ago |
| Edit | Post #288853 |
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— | almost 2 years ago |
| Comment | Post #288874 |
Everyone would have to give their individual reasons, but here are a few that pop out at me:<ol>
<li>The lazy screenshot dump. You didn't bother to properly export the schematic to an image, fix up the image, then post that. The multiple colors and background dots are annoying.
<li>Poor descr... (more) |
— | almost 2 years ago |
| Edit | Post #288874 |
Post edited: Removed annoying time-wasting fluff. Read the rules already! |
— | almost 2 years ago |
| Edit | Post #288877 | Initial revision | — | almost 2 years ago |
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A: Floating circuitry and diodes is the "X" point floating when there is no 12V applied ? Perhaps over a limited range, depending on whether the 12V line is left open or connected to something other than 12V. Case 1: The voltage on X is bounded by the Zener diode. X can't be more than one diode drop below ground, or th... (more) |
— | almost 2 years ago |
| Edit | Post #288853 | Initial revision | — | almost 2 years ago |
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A: Choosing between common-drain JFET amplifier, and common-source The first circuit uses the FET in follower mode. That means it works as an impedance buffer with a gain a little below 1. Such configuration can be useful to turn a high impedance signal into a low impedance signal. The second circuit uses the FET as a common source amplifier. This inverts the ... (more) |
— | almost 2 years ago |
| Comment | Post #288844 |
Those opamp links don't go to datasheets. They go to some product page that asks me to accept cookies. No thanks. (more) |
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| Edit | Post #288784 |
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| Edit | Post #288784 |
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| Comment | Post #288784 |
This is getting off the topic of this question, and is better addressed in a separate question. (more) |
— | almost 2 years ago |
| Edit | Post #288784 |
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— | almost 2 years ago |
| Edit | Post #288784 | Initial revision | — | almost 2 years ago |
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A: Ground pour on outer layers on 4-layer PCB I would not do deliberate ground pours on a board like that. It's relatively small, and not exceptionally high frequency. I also wouldn't try to guess what effect or not it might have on the board fab process. I've put similar microcontrollers on larger boards many times and not had any issues l... (more) |
— | almost 2 years ago |
| Edit | Post #288757 | Initial revision | — | almost 2 years ago |
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A: How to convert dv/dt of noise into frequency for filter capacitor selection? It looks like you've sort of re-discovered a motivation for Fourier analysis. The difference between looking at slope versus frequency content is exactly the difference between time domain and frequency domain analysis. Both are perfectly valid and provide the same ultimate answers. However, one o... (more) |
— | almost 2 years ago |
| Edit | Post #288740 |
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| Edit | Post #288740 |
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| Comment | Post #288641 |
I don't see anything wrong with a question that was prompted by current events, as long as it asks about real EE issues like design tradeoffs. In my opinion, this question meets those criteria. (more) |
— | almost 2 years ago |
| Edit | Post #288740 | Initial revision | — | almost 2 years ago |
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A: Should posting on Meta affect reputation? Yes, votes on meta should not factor into rep. Meta downvotes indicate disagreement, not that you're a terrible person, have the IQ of a garden slug, and cast dispersions on your heritage like they do on the main site ;-) Users should be free to express their opinions, whether popular or not, as ... (more) |
— | almost 2 years ago |
| Comment | Post #288688 |
Tell us what you ultimately want to achieve, not how you imagined to go about it. All you've said is that you want to *"generate strong magnetic fields"*. Driving an electro-magnet does not necessarily require resonance. Maybe a class D amp? "Strong" is a useless spec, so we have no idea of what ... (more) |
— | almost 2 years ago |
| Comment | Post #288641 |
What's with the downvotes? This question is well written, to the point, uses pictures well to illustrate the point, and is a legitimate question prompted by current events. It's not asking a user-level question about a game controller, but design issues that make products suitable for different use... (more) |
— | almost 2 years ago |
| Edit | Post #288708 | Initial revision | — | almost 2 years ago |
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A: High power LC circuit with programmable resonant frequency What you are asking for is totally unrealistic, and your numbers don't add up. With 10 mH and 80 µF, the resonant frequency is 178 Hz. Getting down to 1 Hz even with 10 mH would require over 2.5 F. Keep in mind that with the inductance fixed, the capacitance required for resonance is inver... (more) |
— | almost 2 years ago |
| Edit | Post #288652 | Initial revision | — | almost 2 years ago |
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A: Titanic submarine control considerations I don't have any special knowledge about how submarines get controlled, so this is mostly speculation. I expect that the actual controls are fine. There seem to be the necessary degrees of freedom, and as you say, people are already familiar with the interface. In that sense I don't see anything... (more) |
— | almost 2 years ago |
| Comment | Post #288550 |
@Lundin So say that in an answer. It's OK to answer with speculative information as long as it's labeled as such. I don't want the information to get lost here in a comment chain. Comments are not for content. (more) |
— | almost 2 years ago |
| Comment | Post #288550 |
@Lundin You should make this an answer. This information doesn't belong in a comment. (more) |
— | almost 2 years ago |
| Edit | Post #288515 | Initial revision | — | almost 2 years ago |
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A: Sensing 3 states in a single mcu pin using firmware Starting with your first circuit: It seems a little klunky, but should work. I don't like the D1 and D2 diodes. The reason I placed D1 is to avoid triggering the mosfet with very low voltage like 2V to 4V. Is D2 really necessary? The input voltage threshold for sensing high is the 8.2 V... (more) |
— | almost 2 years ago |
| Edit | Post #288474 | Initial revision | — | almost 2 years ago |
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A: How to change the polarity of an input using a single switch? The difference between your two options is which polarity the input floats to when left open, and whether there is an overall inversion. Adding the inversion in the firmware would require one more pin from the chip. Not necessarily. I was envisioning inversion or not would be specified by conf... (more) |
— | almost 2 years ago |
| Comment | Post #288440 |
It seems you want to be able to invert the sense of an input into a microcontroller. Why not do the inversion in the firmware? There should be no need for hardware polarity flipping. (more) |
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| Edit | Post #288415 | Initial revision | — | almost 2 years ago |
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A: Variant of a Mosfet's Gate-Source protection If the TVS truly clamps the "+12V" line to 25 V, then the VGS of Q1 can't exceed 25 V. However, if you want to limit the gate voltage, limit the gate voltage. A Zener between gate and source guarantees that directly. You may still want the TVS to clamp the incoming power voltage for other reason... (more) |
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| Edit | Post #288391 | Initial revision | — | almost 2 years ago |
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A: Why do I need electrodes for ECG measurements? The electrodes electrically connect to the skin in order to pick up tiny signals produced by the heart muscles. Electrically you're a bag of saltwater. Your skin (the bag) has a relatively high resistance. The innards (the salt water) has relatively low resistivity. To get good signal to nois... (more) |
— | almost 2 years ago |
| Edit | Post #288390 | Initial revision | — | almost 2 years ago |
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A: Synchronization of clock of satelite with devices here on the Earth First, the time dilation experienced by a satellite is tiny on a human scale. It takes sophisticated algorithms and lots of processing power to measure time differences between a spot on earth and various satellites. That's how GPS works. Early GPS receivers were rack-mounted boxes before integrat... (more) |
— | almost 2 years ago |
| Edit | Post #288233 |
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| Edit | Post #288233 |
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| Edit | Post #288233 | Initial revision | — | almost 2 years ago |
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A: Oscillator with non-rechargable battery There actually seem to be two different questions here. Can a primary (non-rechargable) battery be damaged by forcing reverse current thru it? Yes. Primary batteries are only intended to source power, not sink it. Forcing reverse current thru them, especially for significant lengths of time, ... (more) |
— | almost 2 years ago |
| Edit | Post #288231 | Initial revision | — | almost 2 years ago |
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A: Confusion in operation of analog computer The poteniometers (what you label as "variable resistors") are almost certainly just floating pots. If their ends were permanently connected to power and ground, then they'd be voltage sources, not pots. You might temporarily connect the top terminal to power, the bottom to ground, and measure the... (more) |
— | almost 2 years ago |