I'm hooking up a microcontroller to be able to turn a bunch of computers on/off remotely. This is via the soft switch on the motherboard which doesn't carry any kind of load.
Looking at relays, the 5v one is slightly cheaper than the 12v one, both are 1A which is far overkill.
Does anyone know if I can save 5 cents by going with the 5v relay or do I have to splurge on the 12v ones?
Best Answer
For, specifically, an "ATX" flavor power supply, every one I've looked at (and, I believe the standard they are built to) is a 5 volt logic signal, pull low to turn on.
However, it's certainly possible that some more modern than the junk I work with (after it's done computing, giving it a new purpose in life) might use 3.3 volt logic (most of the supplies I've got experience with do have a 3.3V output, but the power on signal is a 5 volt signal.) There seem to be MANY revisions of the standard, more than I care to sort through.
You might also want to make use of the "power good" logic signal, depending what you are doing.
You may not need a relay at all.