First I'll refer you to this article:

http://autospeed.com/A_107975/cms/article.html

And the wiring diagram:



Now, I understand the circuit and how all of it works, but I have a question about the DPDT relay. I usually only work with the SPST or SPDT relays, so this DPDT's something new. When it's used in this diagram, am I safe to use a DPDT relay that's rated relatively low for current, say 1A or 5A?

I'm thinking that 1A or 5A would be fine since the DPDT relay is kind of just acting like a switch, energizing the coil in the second relay.

 

Yes you can use a 1A-5A DPDT relay, the current demand of a LED or relay coil is probably less the 500mA. 94

 

I wonder if Fry's carries dpdt relays... It'd be 10x easier than ordering them online.

 

You could just use two SPDT relays in place of the DPDT relay. 94

 

Well crap, I went to a electronics store today and was totally overwhelmed by the DPDT relays I saw. Some had six contacts, some had eight, some had wayyy more!

I think I'll stick with the DPDT just for the sake of learning how it works. (That and it would take me some serious time to reconfigure the whole thing with 2 SPDT's since I'm a total newb at this =p).

 

A 4PDT relay will be more common then a DPDT, just use two of the poles. 94

 

After some quick reading, I finally figured out what the number's before the PDT mean. Thanks!