Hi all,

I need a 5v relay but the signal input needs to be 12v. Would I be correct in saying, all I need to do is swap out the J3Y NPN for another NPN transistor that can handle 12v at the base?

Thanks,
Mike.

 

I need a 5v relay but the signal input needs to be 12v. Would I be correct in saying, all I need to do is swap out the J3Y NPN for another NPN transistor that can handle 12v at the base?

No.
Just add a small diode (e.g. 1N4148) from the transistors base (anode) to emitter (cathode).
But your schematic shows a PNP, not an NPN.

 

Sorry wrong schematic. Updated now. What will the diode be doing?

Thanks.

 

Sorry wrong schematic. Updated now. What will the diode be doing?

For that you don't need the diode.
The base will handle the 12mA from a 12V input just fine.
The forward base-emitter voltage looks like a forward biased diode with about 0.7V drop.

 

I appreciate your help. I managed to find another relay to try it out and it worked. I tried it on a previous relay a while back (same make and model) and the transistor got too hot to touch. It must have been a dodgy one.

Thanks.