Posts by Olin Lathrop
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 t...
PCB antennas are not designed by electrical engineers, but guys with pointy hats and wands They use trial and error after starting with the result of some mystic ritual including lots of mumbling ...
Sometimes cables between utility poles make a loop and do a U-turn. What is the purpose of such loops? The loop I'm asking about is in the lower set of wires towards the left of the picture. The...
This sounds like it could be a Paper (https://electrical.codidact.com/categories/35) if written up nicely. It doesn't make sense as a question because you're telling, not asking. I haven't heard ...
Repair questions can be on topic if it's about the underlying electronic principles. Just "How do I fix this?" is off topic. There is little wiggle room for trying to repair a consumer device tha...
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: No...
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...
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...
Here is a basic diagram of the power feed to your house, according to what the power company said they found: R1 represents the additional series resistance due to the cable being corroded. R2 re...
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...
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 m...
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. As you say, Q1 is a switch to control ...
I'm trying to drive a relay according to a 5 V digital signal, using this circuit: It works for a while, but then the transistor fails. When I replace the transistor, it works for a while again, ...
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 ...
Thanks for asking. In my view, if it's something you'd first think of asking an electrician, it's probably off topic here. That includes what type of cable to use, whether it should be in a condu...
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...
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...
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....
That's a rather strange thermal relief pattern. It's also not clear where the hole is supposed to be. A proper thermal pattern has a plated hole and annular ring around the hole as usual. Then t...
I see you already have an answer based on the device physics. I'll answer that this means in a circuit. BJT (bipolar junction transistors) do work in reverse, at least somewhat. Generally, the c...
"Stream" and "memory mapped" should be defined in the documentation for whatever microcontroller you are using. "Memory mapped" can mean different things. It might be just a different way of sayi...
Whichever you choose. I notice that you deliberately made the gain of one transistor a little higher than the other. That is irrelevant. The positive and negative outputs don't depend on the pow...
Reasons this is sometimes done: To get higher power dissipation. To get higher voltage capability. To get lower parasitic capacitance. For 1 and 2 the "normal" answer is to use a resistor rat...
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 powe...
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 ...
