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Activity for Olin Lathrop‭

Type On... Excerpt Status Date
Edit Post #291312 Initial revision 6 days ago
Answer A: Control logic for mosfet in piezoelectric energy harvesting circuit
I'll take it that you want this circuit to actually work, not just appear to work in some software simulation. In that case, it's about the circuit, not the simulator. A simulator is just one tool in designing or verifying a circuit. A brain and a calculator are usually much better tools. First...
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6 days ago
Edit Post #291239 Post edited:
20 days ago
Edit Post #291239 Initial revision 21 days ago
Answer A: What are these mystery components (one of wire coil, another labeled "100-10L A9")?
The component with the coil of wire is an inductor. Judging from the small size, it is probably only a few &micro;H. There are lots of uses for inductors, like for filters, switching power supplies, tuned oscillators, and others. I would not try to guess the use from this scant information. The...
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21 days ago
Comment Post #291215 Make it readable, with properly defined axes. I see Andy has given you some suggestions. I'm not going to repeat basic presentation lessons you should have learned in grade school.
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25 days ago
Edit Post #291215 Initial revision 25 days ago
Answer A: Determining the output swing, output common-mode range and input common-mode range in a differential amplifer
First, common mode is something that only applies to a differential signal. When a signal is encoded in the difference between two voltages, the common mode voltage is the average of the two. The common mode range is the range of common mode voltage over which a small differential signal can stil...
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25 days ago
Edit Post #291093 Post edited:
about 1 month ago
Edit Post #291109 Post edited:
about 1 month ago
Edit Post #291109 Initial revision about 1 month ago
Answer A: Regulated charge pump design
That circuit is drawn rather obfuscated, but it does seem to make sense: Start by looking only at D1, D2, C1, and C2. Pretend D3, C3, and D6 don't exist. Although not drawn very well, this is a basic charge pump. For simplicity, let's pretend the diodes are ideal. The actual output voltage...
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about 1 month ago
Edit Post #291093 Initial revision about 1 month ago
Answer A: Step voltage 750kV lines
It's really not clear what exactly happened in that video. We see someone slinging a hook over the power line, then we see a white picture. We don't know what the cable was made of and where the other end really was at the time the hook reached the power line. One possibility is that the cable w...
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about 1 month ago
Edit Post #291082 Initial revision about 1 month ago
Answer A: MAX485 transceivers breaking, Pi filter generating spikes?
At first glance, your design looks reasonable. I assume D1 and D2 are really supposed to be on opposite data lines, and them both being on the A line is a typo? One thing that sticks out to me is the value of the clamping diodes. Why so high? What's your expected common mode range? A large com...
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about 1 month ago
Edit Post #291038 Initial revision about 1 month ago
Answer A: 1-wire interface overvoltage protection
It's been a while since I did 1-wire, so I don't remember the current levels. R18 seems rather high for supporting the minimum required voltage at the maximum possible current. Let's say for sake of example that your 1-wire device is specified to work down to 2.0 V. You're already going to lose ...
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about 1 month ago
Edit Post #291026 Post edited:
about 1 month ago
Edit Post #291026 Initial revision about 1 month ago
Answer A: MOSFET drain current ringing in saturation region
Your controller is too fast compared to the plant (the thing being controlled), thereby causing instability. The most obvious culprit is the 50 k&Omega; resistor between the controller output and the FET gate. The resistor and the gate capacitance low pass filter the control signal, which effecti...
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about 1 month ago
Edit Post #290863 Question closed 2 months ago
Comment Post #290863 No. You didn't supply what was asked for. This question really should have been closed originally due to lack of information. I'll go fix that now.
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2 months ago
Edit Post #290875 Post edited:
2 months ago
Comment Post #290874 I think keeping the electrodes clean will be a problem. Gold should be inert enough, even in seawater. But the chlorine in the salt has a way of getting into everything eventually. Soldermask might survive long term in clean water, but I'd really want to do accelerated aging tests before expecting...
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2 months ago
Comment Post #290874 Do you really only need to know whether the water is up to a certain level, or are you ultimately trying to sense the level. If the latter, there are some technologies you might not be aware of. A company I work for specializes in measuring levels in tanks, and things like the draft of ships. We h...
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2 months ago
Edit Post #290875 Initial revision 2 months ago
Answer A: PCB as a wall of an underwater enclosure
I guess it would work. I have used electrodes on a PCB to detect whether water level got high enough to turn on a sump pump. It worked, although it hasn't been installed very long. In that case the PCB extends upwards to where it is dry. That's where wires are soldered that go to the detection ...
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2 months ago
Comment Post #290863 What you are asking can't be answered without knowing the purpose of each connection to ground. We need to see both the layout (which you provided) and the schematic.
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2 months ago
Edit Post #290839 Initial revision 2 months ago
Article Phone fix adventure case study
I've had a Nexus 5X smart phone since 2016, so now in Feb 2024 it's almost 8 years old. I like the phone and have had no problems with it until three days ago. I had it in the car plugged in and connected as usual when I noticed it rebooting. I thought that was a bit odd, but figured maybe that wa...
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2 months ago
Comment Post #290785 @#8062: <i>"initially it could provide 10-15 minutes of runtime"</i>. Where did you see this? I looked all over for such a spec, but didn't find it. I checked in the user manual and on the web page the device was sold from. The web page just has a dash where the runtime would be (see above), and ...
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2 months ago
Comment Post #290779 @#8049: Yes, there is more to it than just Ah capacity. However, it's a start, and I was trying to keep things simple.
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2 months ago
Edit Post #290785 Initial revision 2 months ago
Answer A: Why would a standby UPS fail to power devices when there's no power outage?
Now that you've supplied a link to the product, I can provide a different take on this affair. Your "UPS" is an Amazon Basics model described at https://www.amazon.com/gp/product/B073Q3BSPG/?th=1. First, it's clear that unit is optimized for one parameter only, which is minimum possible price whi...
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2 months ago
Edit Post #290774 Post edited:
Edited link from a comment into the question
2 months ago
Edit Post #290779 Initial revision 2 months ago
Answer A: Why would a standby UPS fail to power devices when there's no power outage?
I see that manassehkatz has already given you a good answer and plausible explanation for what you observed, so I'll fill in a few other points. Your battery is 5 years old, so is getting to the point where it could start to fail. I wouldn't expect a 5 year old battery to be bad, but it's to the ...
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2 months ago
Comment Post #290720 You are assuming the domed buttons are capacitive switches. Maybe they are, but I wouldn't rule out that they are simple mechanical contacts. In all the products I've worked on that had these kinds of domed buttons, they were just switches. The on-resistance was up to about 200 &Omega; or so. I c...
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3 months ago
Edit Post #290689 Initial revision 3 months ago
Answer A: What type of button is this on a remote control
Such a domed button is usually called a "membrane switch", at least here in the US. As you say, the small metal bubble makes contact with something underneath when pressed. Advantages of membrane switches over the capacitive or conductive sense switches in the rest of your remote include better e...
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3 months ago
Edit Post #290601 Post edited:
3 months ago
Edit Post #290601 Initial revision 3 months ago
Answer A: estimation of pogo pin resistance
Is there a scientific way to estimate the resistance of a pogo pin? Ultimately there must be, but it generally requires knowing things you don't know. Worrying about the resistance of the barrel and spring is missing the point. The limiting factor will be the small contact area between the cir...
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3 months ago
Edit Post #290595 Initial revision 3 months ago
Answer A: High voltage transformer design
When should a transformer core be potted? Whenever you need some of Mechanical ruggedness. High dielectric strength. Minimize vibrations (and therefore audible whine) from capacitive, inductive, piezo-electric and magneto-restrictive effects. Can I place the high voltage conductors...
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3 months ago
Comment Post #290541 Yes, if you isolate the TX and RX signals, then you get around the bi-directional problem. Now you have to isolate at each interface to the bus, though.
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3 months ago
Edit Post #290541 Initial revision 3 months ago
Answer A: Most reliable galvanic isolation technology for extreme EMI environments?
My first knee-jerk reaction was to use opto-isolators. There are some that have been around for decades and are unlikely to go obsolete any time soon. I wasn't previously aware of these "digital isolators". They seem like they go thru a lot of trouble to ultimately do what opto-isolators do. I'...
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3 months ago
Edit Post #290501 Post edited:
4 months ago