Hi,
I was trying to connect my arduino to a 4N25 optoisolator. I had an arduino digital pin going to pin1 of the optoisolator, and pin2 of the optoisolator going to ground (I did not put a resistor between the arduino pin and pin1 of the optoisolator). When I plugged it in, the piece marked 501K (by the port) became blazing hot in a few seconds. I am totally new to electronics and have realized I am trying to go too fast. Could anyone explain what I did, and what the 501K piece is?
Thanks!
You basically connected a diode directly between an output pin and ground (the LED inside the optoisolator). That will draw way too much current from the Arduino pin, and you absolutely need a resistor there (330 ohms is good for this application).
I'm not sure what the 501K is but you're probably referring to the voltage regulator on the board. It will get hot as you draw more and more current from it.
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Thanks! Im hoping I didn't jack anything up too bad from doing this. The pin still works, the optoisolator not so much. Guess its smart to buy several of everything when ordering online instead of just one lol.
Looks like the 501K is:
MF-MSMF050-2
BOURNS
FUSE, PTC RESET, 15V, 500mA, 1812
Holding Current:500mA; Tripping Current:1A; Initial Resistance Max:1ohm; Operating Voltage:15V;