Posts by Olin Lathrop
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 ...
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 ...
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 ...
I was hiking around the Berkshires in western Massachusetts yesterday, and came across this metal panel where some power lines were crossing a ridge: The panel is a few meters wide, and appe...
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...
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...
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...
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...
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 th...
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...
Summary "Outdated" should be used for "this won't work anymore today", not "we would do this differently today". Detail "Outdated" should be reserved for when an answer is wrong or misleading be...
Can anyone explain the theory behind this pin You have already done so yourself: used to give a common mode stabilization and thereby reduce radiated emissions As far as I know, that is exactly ...
What is a typical value for capacitance of a real inductor? "Typical" capacitance is a useless to design circuits with. It will also vary considerably by inductor size, geometry, and materials us...
What the "appropriate" value of R1 is depends on what you are trying to achieve, which you haven't told us. Will this device be used in bright light, like outdoors, and the LED therefore needs to ...
Your circuit It doesn't make sense that the yellow blob is a current sink: If it were a current sink, then there would be no point to the resistor in series with it. That only wastes power, re...
"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...
First Circuit Let's start by looking at the conventional current mirror circuit: The base of Q1 (Not sure which one that is? Use component designators next time!) is driven to whatever it takes...
This is a good question. I wasn't originally envisioning introductions to known concepts, but that might work if well written. If so, the Paper should at least be clearly labeled as such. We don...
Sorry I didn't notice this earlier. We definitely don't just want to import questions and answers directly from SE. This has been discussed several times on various Codidact sites. Some of the f...
say that materials should be small and focused There are many many theories of how to best present information. Any one or two particular opinions aren't really relevant, especially since there i...
EMPs (electro-magnetic pulses) occur naturally often. Every lightning strike is one example. Larger EMPs have been created artificially with nuclear weapons. The Starfish Prime H-bomb test cause...
To summarize, it seems you want a circuit that will detect an input voltage high/low with a threshold somewhere between 0 and 3.3 V, must operate correctly with 0-3.3 V input, but must tolerate inp...
