Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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1500 questions
32
votes
11 answers

Do you layout in mil or mm?

I have been using 10 mil trace with 10 mil spacing. The PCB vendors quote that they like traces down to 7 mil. But then I ran across a PDF showing how to fan out a QFP to get all the signals accessible. They use millimeters because the QFPs are…
Robert Deml
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What exactly are harmonics and how do they "appear"?

From reading so many sources online, I still cannot grasp why a different waveforms have harmonics. For example: when designing a silly amplitude modulation (AM) circuit that puts a square wave from a microcontroller in to an antenna, how are…
John Quinn
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32
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6 answers

SMD soldering: tiny components stick to tweezer point

When soldering SMD components, the 2-pinned ones (like resistors, capacitors, ...) are the hardest in my opinion. I started long time ago with the 1206 format. Then scaled down to 0804, 0603 and finally I'm working with the 0402 ones. I'm facing a…
K.Mulier
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32
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2 answers

Differences between TVS diode and Zener diodes, in diagrams and in practice?

I have been looking at circuit protection using TVS and Zener diodes. I have seen the following symbols used to represent TVS diodes in circuit diagrams: simulate this circuit – Schematic created using CircuitLab I guess the first question is…
feetwet
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32
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1 answer

Active vs Passive Buzzer

I recently borrowed an Arduino Inland Basic Starter Kit. It includes an active and passive buzzer. What is the difference? I can hear a difference in sound when I use the tone() command. Anything else? How can I identify which one is which? Are…
shurup
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32
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5 answers

C standard libraries on bare metal

I am mostly doing development on devices that have ported Linux so the standard C library provides lots of it's functionality through implementing system calls which have a standardised behaviour. However for bare metal, there is no underlying OS.…
TheMeaningfulEngineer
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32
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4 answers

How do I connect components when using a circuit board with pads but no traces?

Given a matrix board with soldering pads but no traces, how would you connect adjacent components (including the ends of the jumpers for longer stretches)? Some possibilities I've come up with: Solder the individual leads as usual, then bridge the…
Redwood
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32
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4 answers

How to measure capacity of a Lithium-ion battery

I bought a Lithium-ion battery for a camera (much cheaper than the brand replacement but non unreasonably cheap compared to AAA Li-Ion batteries with similar charge). I however have doubts that it has the capacity it claims on the package (in mAH).…
user12889
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32
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3 answers

What do the 3 symbols (circle, square, triangle) in the USB Type-A plug represent?

What do the 3 symbols (circle, square, triangle) in the USB Type-A plug represent? Is it power-/data-related notifications or just universal identification for USB?
Ram_HW
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32
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5 answers

Things to watch out when applying FCC CE

I have a Bluetooth remote control device that uses 2 AA batteries. Due to positive feedback and responses, I'm thinking to sell it to the mass market. Thus I need FCC certification. After reading many articles including all the FCC related questions…
Daniel
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32
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12 answers

Reliability of the Arduino platform for industrial use

I'm no electrical engineer (just mechanical) but I would like to apply some of my hobbyist experience to my job and implement various automated systems in an industrial (manufacturing) environment. Traditionally, automation in the industrial…
Faken
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32
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12 answers

Opinions on an oscilloscope suitable for hobby electronics on a budget

I'm thinking about getting an oscilloscope as my next tool purchase but I don't really know what I should be looking for or what the options are. Ideally I'd prefer something that was stand alone, but I expect a device that hooks up to a PC for the…
Len Holgate
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32
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4 answers

What do the arrows in transistor symbols point to (and from)?

Transistor symbols are often drawn with arrows pointing in one direction or the other, depending on type, like in the following symbols: But what is the arrow actually pointing at? And from where are they pointing? Is it the same principle behind…
Tron
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32
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6 answers

"Ground" vs. "Earth" vs. common vs. negative terminal

This may just be me not having a degree in electrical engineering or electronics, but the whole notion of "ground" and "earth", when used in electrical circuit diagrams (especially integrated circuits), is extremely confusing. I guess the whole…
jrista
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32
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7 answers

Why have two NOT gates in series?

I have recently been looking at the datasheets for the 74HC139 IC in order to see if it was suitable for my project, and have come across the following logic diagram which strikes me as a little bit odd: simulate this circuit – Schematic created…
Thomas Russell
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