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1500 questions
44
votes
8 answers
What tools, equipment, and techniques do you use to solder fine-pitch SMT parts?
Possibly many questions have been asked on soldering smd parts, but I haven't found specific answers, Like:
Do you use a watchmakers lens or some other type of magnifying glass while soldering these miniature components? What would be most optimum…
Kevin Boyd
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44
votes
4 answers
Can somebody explain what IQ (quadrature) means in terms of SDR?
This is a bit of a basic question, but I am having trouble understanding why a signal needs to be broken up into I and Q components to be useful for software-defined radio (SDR).
I understand that the I and Q components are the same signal, just 90…
Malvineous
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44
votes
8 answers
How are current and voltage related to torque and speed of a brushless motor?
I know that electric vehicles have different performances depending on battery and motor, but it's not clear how electrical and mechanical units are related.
Will a 100V motor raise against slopes better than a 50V motor?
jumpjack
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44
votes
6 answers
Why do CRTs have 3 electron guns?
I have been wondering about this for a while:
Since the phosphor will remain excited for a certain period of time, I could imagine a single electron gun could target the red, green and blue phosphors sequentially instead having 3 parallel…
Thomas
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44
votes
5 answers
Why do 7 segment LED displays break apart when I brush my teeth?
This question might sound silly, but it is very serious (although geeky, I must admit).
When I use my electric toothbrush in front of my alarm clock (one of those with a big red LED display), the numbers seem to break apart. Why?
With my current…
Max
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44
votes
2 answers
What is the failure mode of a solar panel?
I have understood that solar panels don't last forever. Warranties are typically a couple dozen years, and you can expect your panel to last for perhaps twice the warranty period.
But what does exactly happen when the panel is failing? Does it fail…
juhist
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44
votes
8 answers
What is the truth about 1.5 V "lithium" cells?
At least one manufacturer out there is marketing "Lithium" cells in familiar AA and AAA sizes, as direct replacements for those standard 1.5 V sizes, boasting the typically better than alkaline longevity you'd expect from lithium.
But we all know…
Randy
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44
votes
8 answers
Why are car batteries still so heavy?
Back when I was a kid, car batteries used to be huge heavy lumps of plastic filled with lead and acid. They used to weigh almost as much as a mobile phone (slight exaggeration there, sorry).
45 years later, car batteries still look the same and…
user130311
44
votes
2 answers
How do media buttons on a plain wired headset work?
I mean the simple analog headset pluggable into the jack of a phone. Not USB, not bluetooth, not fancy proprietary plugs with extra connectors - just a generic stereo+mic jack.
The four "bands" on the jack plug are GND, right earphone, left…
SF.
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44
votes
9 answers
What is the reverse recovery time in a diode?
What is the reverse recovery time in a diode?
Cell-o
- 869
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44
votes
8 answers
Smallest AES implementation for microcontrollers?
Can anyone recommend a small, free implementation of AES-128 Rijndael for microcontrollers. Ideally, for the PIC18, though a general implementation in C would be useful.
Compiling the axTLS implementation for PIC18 and encrypting/decrypting a block…
Toby Jaffey
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44
votes
4 answers
When to use Capacitors?
This is probably the dumbest question ever, but I am an electronics nublet.
I understand what capacitors do, and I've been reading beginner Electronics books and such, but I don't quite understand when to use them? Sometimes in these books they just…
user3073
44
votes
15 answers
What are low cost circuit and PCB design software?
Do you know of any freeware or low cost circuit / PCB design software?
I know a few which I have listed below but I was wondering if there were more of its kind. Please mention the good features and issues you've faced with the software.
Edward
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44
votes
4 answers
How does a Crystal work?
Specifically, a 2pin and 4pin quartz crystal oscillator.
What I know: current is applied and the crystal oscillates in order to provide an oscillating signal.
What I want to know: How does the vibration cause an oscillating current? How are 2/4pin…
Sciiiiience
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43
votes
3 answers
What's radiating on my PCB?
I recently did a proper EMC test on a PCB of mine. It failed the test, and seems to be radiating in the 300MHz - 1GHz region, with peaks every 50MHz, and little peaks on the 25MHz.
Looking at the near field, you can clearly see lots of 25MHz…
Rocketmagnet
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