Tagged Questions
3
votes
2answers
293 views
Do I need to use a resistor with a microswitch to limit current for an Arduino Uno?
I'm using an Arduino Uno to control a small robot and I'm starting to add micro-switches as bump-sensors. I know that when I'm creating a circuit with LEDs I need to use resistors to limit the current ...
8
votes
3answers
373 views
Blowing a Fuse to Permanently Disable Functionality
Certain electrical designs require permanently disabling hardware functionality on the fly. Sending an overcurrent to a weak fuse may be a method for accomplishing this, breaking the circuit in a ...
3
votes
4answers
224 views
Current over ethernet?
It seems that the voltage over ethernet ranges from 2 to 3 volts. How much current typically runs through the wires? I tried Googling with no success.
I ask this because I'm looking for components ...
2
votes
2answers
127 views
How does a large electric switch different from small?
Why do some electric appliances require to have a large electric switch to turn them on or off? If I use a small switch where a large switch is required, would there be potential possibility of ...
0
votes
2answers
388 views
Converting an NO reed switch to a NC with lowest leakage current
When the switch is closed I need the pin on the microcontroller to be high impedance, when the switch is open I need it connected to the ground. I need the leakage current to be minimal.
What should I ...
10
votes
4answers
807 views
Why does electric arc in a switch prefer a curved path over a straight path?
Recently I found this video of a 500 kilovolts line being opened under load.
When the switch contacts are pulled apart an electric arc predictably starts. While the contacts are close to each other ...
22
votes
7answers
5k views
Why does a resistor need to be on the anode of an LED?
Please be kind, I am an electronics nub. This is in reference to getting an LED to emit photons.
From what I read (Getting Started in Electronics - Forrest Mims III and Make: Electronics) electrons ...
2
votes
4answers
568 views
How many resistors do I need for an 8 switch DIP switch block?
I was thinking of giving each switch it's own pull-up resistor, but this seems like it would be expensive and a little bit of overkill. But using just one pull-up for the entire block seems like it ...
8
votes
3answers
1k views
Need help operating a transistor
I have a relay operated by an NPN transistor that needs some voltage applied to the base. I'm working with an arduino and if I give it a digital port, all's well. The circuit looks like this one:
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