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1500 questions
33
votes
2 answers
How do computers calculate sin values?
How does a computer calculate a sin value? Logically, when I think about it the only apparent way is to put many sin values into memory, and when a sin value needs to be "calculated" it would just pull data from a specific memory address.(ex. sin(x)…
zack1544
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33
votes
3 answers
Why 3 phase and not 1 phase power transmission?
Why does power transmission use three lines with three different phases? Why not three lines all in the same phase? Does it have to do with the alternators used for generating the power, or is there less loss when the phases of the three lines are…
Geremia
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33
votes
6 answers
How did smacking electron tube TVs help?
In old movies (or new movies playing in these times), I often see people smacking the top of electron tube TVs or screens. Somehow it seems to help to stabilize/sharpen the picture. But why?
Are there any reasons an electronic circuit could go from…
OddDev
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33
votes
6 answers
Slow Blow vs Fast Acting Fuse
Is there any way to tell the difference between a slow blow and a fast acting Fuse? I had one blow in my amp and I know its 125v 5a, but i'm not sure if it is a slow blow or fast acting fuse.
Is there any way to discern the difference after one has…
Sean
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33
votes
8 answers
Current flow in batteries?
I am reading a basic electronics book: "There are no Electrons: Electronics for Earthlings" and I came across a clever passage about the fact that you need a closed circuit in order for current to flow. Here is the passage I am curious…
mike
33
votes
12 answers
Multimeter exploded during ACV measurment - What did I do wrong?
simulate this circuit – Schematic created using CircuitLab
A DT-830B meter.
I bought a new transformer, and I was trying to measure the output voltage. I plugged the probes on 'VΩmA' (not 10 A) and COM. and set it to 750(not 100% sure if i put it…
user100933
33
votes
7 answers
How do I use the printf function on STM32?
I am trying to figure out how to use the printf function to print to the serial port.
My current setup is STM32CubeMX generated code and SystemWorkbench32 with the STM32F407 discovery board.
I see in stdio.h that the printf prototype is defined…
user505160
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33
votes
7 answers
Can thin sections of copper traces be used as fuses?
Is it safe to use thin sections of copper traces as one-shot fuses when cost is important, but when it is also vital to protect the rest of the circuitry? Should the solder mask be removed at that location? What about using 0R resistances in small…
Mister Mystère
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33
votes
8 answers
Why is it dangerous use a coiled extension cord?
What aspect of using a coiled extension cord makes it more dangerous than using an unrolled power cord?
Many fire safety websites say that an extension cord should not be used while coiled.
Is this due to the cord acting as an air core inductor? I…
Hugoagogo
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33
votes
10 answers
AC: Why differentiate between Ground and Neutral?
Current flows through a conductor connecting points at different potentials.
Leaving aside multi-phase details, common/conventional AC systems use a 3-wire setup:
Wire-1: a line/live/hot/phase wire presenting a point that oscillates between 2…
BVN
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33
votes
4 answers
Ceramic capacitors: how to read 2-digit markings?
Related question: Ceramic capacitors: how to read 3-digit markings?
I have some ceramic capacitors with a 2-digit marking. How to read them? Do the colored markings at the top mean anything?
Image description:
Brown ceramic capacitors with 10…
Denilson Sá Maia
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33
votes
3 answers
How can I detect a power outage with a microcontroller?
I have the following power supply configuration:
AC MAINS -> UPS -> 24V POWER SUPPLY -> 5V VOLTAGE REGULATOR -> PCB (microcontroller).
What's the best solution to detect the power outage on the mains with the microcontroller?
I also need to detect…
m.Alin
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33
votes
5 answers
What makes solder harden?
Soldering wire is very soft and pliable, but solder on a circuit board is hard. Why? I haven't been able to find a definitive answer, but some ideas that come to mind are:
Some kind of chemical reaction that takes place when the solder is heated…
Michael
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33
votes
3 answers
Negative frequencies: what is that?
I know that when the frequency is 0, the voltage will be pure DC. But in DSP and Digital Communication, I have seen mentioning of negative frequencies which I dont quite understand. For example, like \$ -f_{0}\$ to \$ f_{0}\$ frequency range. How…
0xakhil
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33
votes
5 answers
How does a capacitor smooth energy?
I'm trying to wrap my mind around how capacitors work. I understand they store a charge and generally understand how but I don't understand how using them "smoothes" the flow of the charge. Doesn't, say a motor, drawing power from a charged…
Michael Rader
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