Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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1500 questions
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7 answers

How do I calculate the power rating for zero-ohm resistors?

Based on my earlier question, since there supposed to be zero voltage (V=IR) drop across a 0 Ω resistor, how do we select the power rating of such a component? For example, let's say I were to connect a zero-ohm resistor in between 5 V power source…
Dennis
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What microprocessor for experimentation?

I harbor a secret fantasy (oops, not so secret anymore) to build a simple computer from scratch. I'm looking for an easy-to-use microprocessor to start with. I know about the usual suspects such as the 6502, 68000, 8086, Z80, etc. But I'm wondering…
Barry Brown
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Why don't interfering radio stations both play at the same time?

Since radio-waves are additive, I would expect that overlapping stations (eg. two different signals broadcasting on 95.7 within range) to both play over my radio at the same time. But that's not what happens. Instead, I hear only one station at a…
BlueRaja - Danny Pflughoeft
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9 answers

Moisture Trapped in IP66 Enclosure

I got a field report of a product which is sealed in an IP66 aluminum die cast body. it was observed that water/moisture had condensed inside the enclosure over and over and creating some white marks inside (see attached). The product was installed…
Transformer
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Ground ring -- good or bad?

Here are two routings: Which is better? On one hand, the first is bad because ground ring is one-turn coil, hence induction current will be appear. On other hand, the second is bad because potential in the opposite points of ground plane will…
user54579
33
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3 answers

What exactly is prepreg and core in a PCB?

I am trying to wrap my head around the structure of a multilayer PCB, and while I can understand many things, I am not able to grasp the concept of "prepreg" and "core". What do they exactly do? I have attached a reference stackup below. Only thing…
LoveEnigma
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What are the differences between USB and RS232?

Can someone tell me why people use either USB or RS232. They are both serial ports, right? And I understand that USB is much faster (especially USB3.0) but if people wanted too I'm sure they could make a successor to RS232 that is just as…
Sponge Bob
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Please help me identify this odd-looking component

When opening up a car alarm system I found this strange-looking component. I thought that it could be something which is light dependent, but the entire board is enclosed in a black plastic box and the alarm should trigger before the thief reaches…
Daniel Tork
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7 answers

Why does GSM cause speakers to buzz?

Based on numerous internet resources, speaker wire acts like an antenna which picks up the transmitted signal of nearby cellphones and causes the speakers to buzz. But I'm not really buying that... A 3.5 mm speaker cable is designed to carry 1 V.…
JSideris
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PCB colors - what's available, and why?

A question so simple I've never thought about it before. Usually I get my PCBs made in standard green, but have been offered a blue for my next revision of an existing (green) board at no extra cost. What colors are available as standard, and why…
Dirk Bruere
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Does cassette tape change its velocity while playing?

Looking at the old cassette tape, From the POV of the head, let's say that it reads at speed \$v\$ (the magnetic medium scrolls at speed \$v\$). But looking at the right wheel, which is the one that's pooling the magnetic medium - its radius is…
Royi Namir
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What is this cartridge fuse style component?

This is a Sony EVO-9500A (old 8mm tape player/recorder). What is the cartridge fuse style component? It is 1/4" by 1 1/8" about the same size as a 3AG fuse. It has a scale on the front going from 0 to 10 and looks like a thermometer. The only…
David
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Should I really divide the ground plane into analog and digital parts?

I am about to design my first PCB as part of my graduation project. Of course, as the first step, I try to learn as much as possible. A part of the research I found this 3 part article, that suggests that it is not neccessary and in some cases is…
Andrey Pro
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What are some reasons to connect capacitors in series?

Usually you either combine capacitors in parallel because you want to increase the total capacitance while fitting the components in a certain shape/position, or you just combine capacitors by buying a single capacitor of a larger value. Combining…
endolith
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7 answers

What' so great about CMOS?

I've read lot of topics here. I read some people saying I prefer to "have CMOS characteristics" & so on , also in some data sheets (like AVR), they say it have CMOS characteristics, etc... I remember once "CMOS compatible" word? So why having…
xsari3x
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