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1500 questions
56
votes
7 answers
Does a dangling wire really electrocute me if I'm standing in water?
We've all seen this scenario in movies; somebody has to cross a room half filled with water and there is a dangling electric wire that shoots sparks everywhere. The poor person has to cross the room but cannot do so because if the wire hits the…
S. Rotos
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56
votes
3 answers
Fan speed switch: why OFF :: HIGH :: MED :: LOW?
Many AC fans, including inexpensive floor models, have a rotary speed control which rotates from OFF to HIGH to MED to LOW. Since the switch does not rotate 360°, you have to rotate it backwards to shut it off. This has always slightly annoyed me,…
RichF
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56
votes
5 answers
Are LEDs better than we think?
Conventional wisdom about LEDs says their maximum reverse voltage \$V_{R(max)}\$ is quite limited, usually in the 5V-8V range.
So, for experimentation purposes, I wanted to bring an LED into controlled breakdown, using my current-limited power…
LorenzoDonati4Ukraine-OnStrike
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56
votes
6 answers
Do I really need resistors when controlling LEDs with Arduino?
I'm just trying out Arduino Uno for the first time with 2 blinking LEDs on a breadboard. All the tutorials on the Internet seem to use a resistor. I do know the function of resistors, but does it really matter here? These LEDs are working just fine…
40pro
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56
votes
10 answers
Why is an Ethernet cable not grounded?
There is no dedicated GND in the classical Ethernet 8P8C ("RJ45") pinout.[1]
Why does the Ethernet spec not include a ground, unlike many other cable types used for interconnecting devices that may both have its independent power source as well,…
mykhal
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56
votes
7 answers
What exactly is a current source?
What I understood from the definition of current sources is that it is a source which supplies a constant current across a load no matter how the other parameters (like resistances for example) in the circuit are changed. Am I right?
If I'm right,…
Green Noob
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56
votes
3 answers
What's this importance of datasheets?
As someone starting with electronics I keep hearing, "Check the datasheet!"
Why are datasheets so important and what information can I expect to find in them? It seems like a large amount of information would come from experience and know how, not…
stevenvh
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55
votes
7 answers
Why don't we make CPUs with 1000s of layers to make use of space in the third dimension?
I am wondering why don't we make processors such as CPUs with 1000s of stacked layers to make use of space in the third dimension now that we have three-dimensional transistors. To be clear I'm referencing making something of a rectangular-prism…
Ethan
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55
votes
16 answers
Why use PLC instead of microcontroller?
Why does everyone use PLCs in industrial environments, instead of a microcontroller based solution?
For a longer task, the PLC program is as complicated as a microcontroller program.
A microcontroller based solution may be more customisable, and of…
Saneesh A T
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55
votes
7 answers
What is the usage of Zero Ohm & MiliOhm Resistor?
I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design?
Normally if we wish to probe how much current the load is taking, we put a jumper pin across…
Dennis
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55
votes
5 answers
Triac versus Relay
What are the scenarios where Triacs can not replace a relay or vice-versa?
Daniel Grillo
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55
votes
10 answers
Amplification before tubes and transistors were invented
Telephones are older than vacuum tubes and of course transistors. How was signal amplification done?
I mean the technology, not the details.
EDIT
Some additional informations that I should have given at the beginning :
The question is…
andre314
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55
votes
11 answers
Why would clipping a wire cause a bomb to explode?
There are a lot of movies and video games that depict defusing bombs, most of which boils down to picking the right color wire. Something like this:
Now, that's a part I don't understand.
simulate this circuit – Schematic created using…
yuritsuki
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54
votes
8 answers
Personal electronics tool kit
What are the items you have in your personal electronics tool kit?
mad_z
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54
votes
6 answers
Standard PCB trace widths?
Is there a standard for the sizes of PCB traces?
That is are some 25 mil and others 10 mil or is can you choose your own?
I plan to run 400mA through some thicker traces, but less than 30mA for all other traces. About what size would I need?
Thomas O
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