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1500 questions
73
votes
3 answers
MOSFET: Why the drain and source are different?
Why the drain the source terminal of the MOSFET function differently while their physical structure is similar/symmetrical ?
This is a MOSFET:
You can see that the drain and source are similar.
So why do I need to connect one of them to VCC and the…
Dor
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73
votes
6 answers
Why do many laptops run on 19 volts?
Typically mobile devices that have a mains-powered supply will accept voltage that is multiple of some single battery voltage. For example, 4.5 volts is 1.5 volts (AA primary battery) 3 times and 36 volts is 3.6 volts (Li-Ion battery) 10 times.
Now…
sharptooth
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72
votes
6 answers
What is Copper Thieving and why use it?
On many boards I've seen, there are little copper dots used for the purpose of "Copper Thieving". They're small round copper dots connected to nothing and arranged in an array. Supposedly they're for balancing the copper on the boards to improve…
Gustavo Litovsky
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72
votes
2 answers
When to use what transistor
So there are several types of transistors:
BJT
JFET
MOSFET
Combine all that with the various flavors of each (NPN, PNP, enhancement mode, depletion mode, HEXFET, etc) and you've got a wide array of parts, many of which are capable of accomplishing…
Joel B
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72
votes
7 answers
What are the freeware SPICE simulators available?
Does anyone know of a freeware SPICE / circuit simulator?
SPICE (Simulation Program with Integrated Circuit Emphasis) is a general-purpose, open source analog electronic circuit simulator. It is a powerful program that is used in integrated…
Edward
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71
votes
5 answers
Serbia, Kosovo power grid row delays European clocks. Why?
According to this article (and a lot more published today on the same topic), Kosovo electricity net production balance has decreased during the last weeks.
This has led to a small deviation of the European network’s frequency (from 50Hz to…
Evariste
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69
votes
11 answers
How can anyone use a microcontroller which has only 384 bytes of program memory?
For instance a PIC10F200T
Virtually any code you write will be larger than that, unless it is a single purpose chip. Is there any way to load more program memory from external storage or something? I'm just curious, I don't see how this could be…
coder543
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69
votes
8 answers
Why aren't FPGAs ubiquitous?
Reading about FPGAs, if I understand correctly, they are basically fully configurable logic gate circuits. Being this, one can design anything with them. One can design everything in the most customized way possible and hence, meet the same ends in…
Utku
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69
votes
4 answers
What kind of glue should I use for PCB-mounted components to avoid vibrations?
I want to protect the PCB-mounted components from vibrations. What kind of glue/substance should I use?
What are the most prone to failure components due to vibrations?
m.Alin
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69
votes
12 answers
I am a quadriplegic. Would it be possible to power my ventilator humidifier with a battery?
I am an absolute novice in regards to electrical engineering, and so I am hopeful your expertise can guide me in the right direction. I know this is an unusual post for this forum, and so I thank you in advance for your consideration.
First, let…
starbucksguy
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69
votes
4 answers
How to choose a flyback diode for a relay?
A diode is put in parallel with a relay coil (with opposite polarity) to prevent damage to other components when the relay is turned off.
Here's an example schematic I found online:
I'm planning on using a relay with a coil voltage of 5V and…
Nate
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68
votes
9 answers
Difference between latch and flip-flop?
What is the difference between a latch and a flip-flop?
What I am thinking is that a latch is equivalent to a flip-flop since it is used to store bits and is also equivalent to a register which is also used to store data. But after reading some…
Ankur Trapasiya
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68
votes
8 answers
Why is high input impedance good?
Naive perhaps, but
Why is high input impedance a good thing?
Is high input impedance always a good thing?
Everyone
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68
votes
6 answers
How should I use a multimeter to determine which AA batteries to keep and which to toss?
I have a bag of about 50 non-rechargeable AA batteries (1.5 V) that I have collected over the years. I bought a multimeter recently and would like to know the best way to test these batteries to determine which ones I should keep and which I should…
LeopardSkinPillBoxHat
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67
votes
8 answers
Can a circuit be powered from Earth with a return ground on Mars?
Could you use a hot wire (120v 60 hz) from earth and a copper rod inserted into another extraterrestial body (mars) to complete a circuit? If impedance wasn't something to worry about (pretend Mars is only a mile away or something).
I've asked this…
user2476549
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