I bought a 12VDC/10A DPDT Plug-in Relay from RadioShack, but all I got was the socket so far. I want to start wiring for it now because I can just plug in the relay later when it gets here.

The problem is that I don’t know which of the coil terminals 7 or 8 is positive or does that even mater?
Not sure if the polarity would change the direction of the relay coil.

 

Polarity does not matter.

 

Some relays have a BEMF diode and/or a signal LED, if yours has neither then it should not matter, IF they are fitted then polarity matters..
If no BEMF diode fitted, one should be wired across the coil terminals and then the correct polarity should be observed, +ve to cathode.
Max.

 

Some relays have a BEMF diode and/or a signal LED, if yours has neither then it should not matter, IF they are fitted then polarity matters..
If no BEMF diode fitted, one should be wired across the coil terminals and then the correct polarity should be observed, +ve to cathode.
Max.

Well I don’t believe there is a BEMF diode in the Radio Shack relay, but I’m actually soldering a Bridge Rectifiers to the coil input because I have 12VAC supply and I can’t find a small AC relay to use.

 

Well I don’t believe there is a BEMF diode in the Radio Shack relay,

I just mentioned it to cover the bases, I am not sure of R.S. products anymore, they pulled out of Canada about 20yrs ago!!.
Max.

 

You know, now that I think about this particular relay I should have known this because it’s only an electro magnet pulling the contacts down. For some reason I was thinking if the poles were reversed the contacts would want to move away, but in this case the contacts aren’t magnetic.

 

You know, now that I think about this particular relay I should have known this because it’s only an electro magnet pulling the contacts down. For some reason I was thinking if the poles were reversed the contacts would want to move away, but in this case the contacts aren’t magnetic.

The armature is magnetic but not a magnet so polarity is not important.