I'm attempting to have one output on my Arduino drive two relays. I was looking at the schematics for relay shields and they always have one input per relay. I imagine that's just for flexibility right? It's made me start questioning my method of doing it. Here's how I plan on doing it.
I'm having the Arduino drive a 2N2222A transistor which according to the datasheet can handle up to 800 mA from collector to emitter. I'm driving two automotive relays which take 125 mA per relay to drive them. Here's my proposed method of driving them.
groundfungus:
Should work fine, as is, but a couple suggestions, Replace the 1n4148 diode with 1n4001. it will last longer. And I don't see the need for R2.
Thanks. I agree on both accounts after thinking about it.