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1500 questions
22
votes
4 answers
Different PCB color (is it a different material?)
I have acquired this PCB.
The right side of the PCB handles high voltage AC power (250 V maximum,) while the left side handles low DC voltages (24 V maximum.)
They are separated, not only by board cuts, but also with this yellowish line in the…
Malek
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22
votes
4 answers
Should I twist DC power and ground wires from a power supply?
Is it beneficial to twist the red/green power/ground wires from a low-voltage (~5V), relatively low current (1 to 5 A) switching, desktop power supply?
This makes my wire bundle on a desk less chaotic, but will it reduce noise or provide any other…
tarabyte
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22
votes
5 answers
Why can't I see bouncing of a switch on an oscilloscope?
I'm trying to view the bouncing of a simple switch on an oscilloscope.
I have prepared a simple breadboard circuit (power → switch → resistor → ground). The problem is, it is displayed as a perfect square/rectangle on the scope. I have attached a…
Deniz
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22
votes
4 answers
Crystals and load capacitance
If a crystal has a rated load capacitance of 6 pF, is the right thing to do to put a 6 pF capacitor to GND on either leg of the crystal? I'm using it as the clock source (TOSC) for an XMEGA and it's got a max ESR of 50 kOhm (which is within…
vicatcu
- 22,499
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22
votes
7 answers
Necessity of an external watchdog timer
What is the need for an external watchdog timer for a microcontroller?
Most of the microcontrollers are designed with an internal watchdog timer. However, in some of the circuits they are using an external watchdog timer (such as PIC16F1824).
Photon001
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22
votes
9 answers
Make a momentary switch control a toggle
What are the simplest, cheapest, smallest ways to make a momentary switch produce a 2-state toggling output (latching momentary switch)?
In other words, the output is continuously low, and when you momentarily press the button/tact switch, the…
endolith
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22
votes
3 answers
What is the name of this springy type oscilloscope probe accessory?
Exactly what it says on the tin.
How is this pictured accessory called? The obvious place to look for a name would be the probe manual, but it looks like they decided to add the accessory to the package after making the manual, since it's not on…
AndrejaKo
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22
votes
2 answers
Solution for adapting to USB current draw limits?
Summary: I'm setting up a USB-powered Li-ion charging circuit and would of course like to draw the maximum charge current possible situationally -- but also want to ensure I don't violate the USB specification on current draw. While I have been able…
boardbite
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22
votes
10 answers
How exactly does AM/FM carry both pitch and loudness of voice?
Almost every tutorial on AM/FM modulation shows the modulating signal as something like a simple tone or continuous sine wave. Now that's easy, and for AM you just superimpose the modulating signal over the carrier wave as an envelope, and voila,…
aAaa aAaa
- 361
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22
votes
10 answers
Programming languages for electronics engineers
I am an Electronics and Communications Engineering student, before I got to college, I have been interested in programming and computer applications. I had focused on designing Windows applications and learning its techniques, but now, I feel that…
Siraj Muhammad
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22
votes
2 answers
What is a brownout condition?
I'm reading the datasheet of this DAC. Page 27 states:
In many industrial process control applications, it is vital that the
output voltage be controlled during power-up and during brownout
conditions.
What are "brownout conditions"? Why is…
Randomblue
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22
votes
2 answers
Some advice on charging circuit used in simple UPS
I have looked around for some way of having a 5 volt power supply that acts like a UPS.
Basically want to use a micro usb connector for +5 have a battery and li-ion or other charging circuit that will maintain uninterrupted power on the output.
I…
Piotr Kula
- 2,134
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22
votes
5 answers
Resistors - metal film or carbon film and what values?
I am buying a bunch of resistors as a start to my electronics hobby. These are the values I have chosen:
100, 470, 1k, 4k7, 10k, 33k, 47k, 100k, 470k, 1M
Most of my projects will involve microcontrollers, such as the Arduino and other AVR ones. I…
capcom
- 5,882
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22
votes
3 answers
How are multi-layer PCBs made?
I know how normal PCBs are etched, but every time I grab a magnifying glass and examine the edge of a multi-layer board I'm astounded by the precision that must be required during production. On top of that, some of them have buried vias and other…
Polynomial
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22
votes
5 answers
What is the difference between burden resistor and a normal one?
I just came across the word 'Burden Resistor'. Is it any different from a normal resistor?
If it is different, where can I possibly get one? Sparkfun hasn't got one listed. Any help is appreciated. I am trying to build a current sensing circuit.
Daniel Euchar
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