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Can you determine voltage requirements without device specifications?

I've been pulling parts out of old computers and have wondered if I could determine what voltage devices are rated for? For instances small motors and LEDs, it's easy enough to estimate but what if i want more precise information?

gmxx7 years ago
 in general:
       if the part has any info printed on it, you can usually google it to find out. (say i found a voltage regulator, with 7805 written on it. i could google it to find out it is a 5 volt regulator, that it needs 8v to work... so on)

for the computers,
     try tracing the part to its original power connector, you can use the continuity checker on your multimeter. a computer power supply has a 5v, and a 12v rail in the 4 pin molex, and several more on the 20/24 connectors (mostly negative voltage rails)


otherwise, its the controlled release of the magic smoke. :)
Re-design7 years ago
You must have two of the parts.  Hook one into the circuit you are wanting to use it in and power it up starting really low and keep increasing the power and measuring how much it is taking.  When it smokes or blows then you know an approx. maximum.

Put the other good part into the circuit and only power up to 50% of the limit and you should be good to go.