Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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1500 questions
21
votes
6 answers

How does earthing work when earth is dry?

Earthing is meant to provide reliable contact of an electric appliance to earth so that if there's an insulation fault current goes into earth instead of through a person's body. This requires earthing to be made of thick conductors driven deep into…
sharptooth
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Do conductors age under reasonable electric load?

Construction steels are prone to fatigue failure - they get structurally weaker when exposed to repeated mechanical stress. Is there any similar process for conductors which makes them less usable once they conduct current for long enough? In other…
sharptooth
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6 answers

Smallest embedded linux distro?

I like to ask to the experts out there.. What is the best embedded linux distro for: Flash memory ~ 700Kb Ram ~ 256Kb Processor: High end arm cortex M3 (something from STM32 family for eg) Required modules: - Kernel core - Basic driver set:…
Frank
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3 answers

White hairs inside a headphones cable

I have a cheap set of Phillips SHE3000 earphones with a broken wire on the plug. Since I was repairing another set of headphones, with the same problem, I bought an extra plug, just to try repairing them too. Here's my problem - inside the cable for…
sg2002
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4 answers

When is it an instrumentation amplifier (In-Amp) and not an operational amplifier (Op-Amp)?

I've seen a number of different configurations for instrumentation amplifiers, including 2 opamp versions. This is also one. But it's just a differential amplifier preceded by input buffers. When do you call it an instrumentation amplifier, in…
Federico Russo
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2 answers

Why does the SATA power connector have so many pins?

With only 4 cables, two of which are ground, it seems like it has way too many pins. Why is this so?
Filip Haglund
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21
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7 answers

Reduction of DC motor noise

I am designing a circuit with a DC motor 12V DC Reversible Gearhead Motors - 70RPM and some other stuff including a MCU and a LASER, all driven from a single 12V source and am concerned about big HF noise ripple from the motor (electrical rather…
ElecEnthusiast
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9 answers

Sizing SMD components for Hobbyist Kits

More components are only available in SMD packages. For hobbyist assembly the options are to buy breakout boards or solder SMD. Since components are usually packaged in a couple of SMD package types I am trying to put together a set of…
jluciani
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Burned out filament but the light bulb has small resistance

The light bulb shown below is from a Christmas tree light string. The string is made up of series connected light bulbs. However if one burns out, the other bulbs keep working. Taking out the bulb from its socket makes all the others in series with…
Cornelius
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4 answers

Why thermal reliefs on vias?

My EDA software (PCAD, but I guess others do this too) adds thermal reliefs on vias in a copper pour. What's the use? Vias aren't soldered. (I know why you use them on regular PTH pads)
stevenvh
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7 answers

Best methods to fix broken tracks

I've made a couple of PCBs which need the odd few 10 mil tracks, but are mostly 20/30 mil. Unfortunately the etching process isn't fantastic and there are numerous breaks in the traces, most of them small. I've managed to convince solder lumps to go…
user470
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2 answers

2 Voltage regulator wired together to produce higher amperage possible?

I need a 12V 2.56A regulator. I happened to have 2x 2A 12V linear regulators I brought and did nothing with. I was wondering could I wire them together and get 12V 4A or would I have divide my circuit amongst the two regulators? A schematic of how I…
Ageis
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4 answers

Is it bad if I held solder with my mouth?

When soldering, I have on a few occasions, used my teeth to hold a strand of solder while my hands were busy. I do not do this frequently, but sometimes I forget that solder is made of lead and I instinctively use my mouth. How bad is doing that…
Nikita240
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4 answers

How do BJT transistors work in a saturated state?

This is what I know about NPN BJTs (Bipolar Junction Transistors): The Base-Emitter current is amplified HFE times at Collector-Emitter, so that Ice = Ibe * HFE Vbe is the voltage between Base-Emitter, and, like any diode, is usually around 0,65V.…
Denilson Sá Maia
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9 answers

How is the internet able to transmit data so fast?

I'm not sure if I'm in the right place or not, but I figured someone here could maybe provide a good answer. I want to know how electricity is able to flow so fast. For example videos games nowadays, you can shoot someone across the world and they…
Cam Jones
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