I have a scenario where I have two power sources (one from parking light and one from ignition) and depending on whether the relay is energised or not, I want the relevant power source to be the output. So instead of using pin 30 as the common supply voltage, could I use pins 87a and 87 as the two different supplies and pin 30 as the output? I can't think why not unless a relay is one way or something

 

Hello,

The contacts can be used both ways.

Bertus

 

Yes that would work, just decided which supply you want when the relay is de-energised.

 

Both responses are correct. That is the benefit of using a mechanical relay. Solid state relays eor DC applications are usually polarity sensitive.

 

I could I use pins 87a and 87 as the two different supplies and pin 30 as the output? I can't think why not unless a relay is one way or something

The relevant contacts are know as 30 = COM(on), 87a = N.C. , 87 = N.O. ( Normally-Closed/Normally- Open)

 

Thank you all. Worked a treat