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1500 questions
43
votes
8 answers
Am I insane to question that only with a closed path can electrons move?
First of all let me just state that I do not feel confident enough to tell anyone anything about how electric circuits work or anything about the physics behind them because I simply do not know or understand it all.
But I have many times read that…
µDavid
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43
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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43
votes
6 answers
How to connect multiple i2c-interface devices into a single pin A4 (SDA) and A5 (SCL) on Arduino?
I want to add a real time clock module into my little project. I want to display both time and date on my existing i2c 2x16 LCD module.
Both i2c-interface real time clock module and 2x16 LCD module use the same pin A4 (SDA) and A5 (SCL) on Arduino…
banksia
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43
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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43
votes
11 answers
What is the smallest and simplest seed for a random number generator?
A small microcontroller (8-bit Atmel) controls a number of lights in order to present a light show with many fancy randomized light sequences.
A suitable pseudo-RNG does its job nicely, but I'm looking for a good seed for it. A seed will be…
vsz
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43
votes
3 answers
New eagle library: reuse standard package & symbol
I need to make few components in Eagle, which are all in standard packages, and I can see them in ref-packages.lbr.
The problem is that when I am creating my library I don't see how I can reuse package/symbol from another library, so that I only…
BarsMonster
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43
votes
9 answers
How to hold SMD parts in place while soldering?
I go through this every time I have PCBs I need to populate with SMD parts, and this has become more an issue as pin spacings have gotten tighter, and my hands have become less steady with age.
So far I've modified some curved tweezers with a…
Randy
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43
votes
1 answer
What do you need 1.018V for?
The Fluke 732A has among 10V and 1V references also a 1.018V reference (whereas the 10V is the "main" references and the others are formed by resistive voltage dividers).
While having multiple reference voltages is surely convenient, why exactly…
PlasmaHH
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43
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
43
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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42
votes
2 answers
My scope detects a 50Hz signal when the probe is not connected to a circuit, is this normal?
Having no prior experience with scopes, it seems strange to me that when the probe is not measuring anything (~ not connected to a circuit) it measures a small 50Hz (~ my mains are running at 230V 50Hz) signal instead of some random noise. Is this…
damd
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42
votes
8 answers
What is a pull up and pull down?
Can some one explain this terminology please I think I understand it but not completely sure.
I think pull down is where you place a resistor between +V and the other component and pull up is where you place the resistor between 0v and the…
Dean
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42
votes
2 answers
What is a "DIE" package?
In a list of ICs, along with the familiar package names such as QFN32, LQFP48, etc., I've seen a few ICs to be listed as DIE for the package size. I've never seen that description before as an IC package size, and Wikipedia does not list it…
vsz
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42
votes
1 answer
What is / how can I get a student-safe power supply for electronics projects?
What is / how can I get a student-safe power supply for electronics projects?
I'm looking for a student-safe power supply for solder less breadboard. I'm developing a course to teach electrical engineering to grade school students as an…
JJ Rohrer
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42
votes
3 answers
Why is the number 63 popular in electronics?
Capacitors have a voltage of 63V (not 60 or 65).
Fuses have a value of 63A (not 60 or 65).
And there exist more odd values in electronics...
Who knows the history of this convention?
Jan van der Zanden
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