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Replace DPDT switch with relay Answered

Hi there,

I'm currently using a DPDT switch to toggle between power sources (gray dots) I'd like to replace this with a relay, I've added blue dots to my drawing to show (how I think) that should look. Is this correct? My main concern is if I should take the coil resistance into account.

What kind of relay would you recommend? Would any 12V 2A relay work?

Kind regards,


P.s. the 560 ohm resistor is on the other side of the led...


You can replace any switch with an identical relay. If its a DPDT switch then get a DPDT relay. Connect it the same way the switch is connected and your all set. You just need a power source going to the relay coil to switch it back and forth. If your wanting one of the power sources to basically control the relay then yes you will want a DPDT relay that operates on 12V. Then as long as your primary supply is on the relay will stay switched to that supply. When the primary supply is cut the relay will drop to the secondary supply.

Great! So I can indeed ignore the coil resistance?

The coil resistance just gives you a reference for figuring out how much amperage the relay will pull while activated.