I actually found a good SPST automotive relay at radio shack for a reasonable price yesterday for my little project. I was expecting upwards of 12-15$ knowing their prices, but it was like 4.99 or something. Just look for one that is 12V 20/30A rated SPST (or SPDT if you need?) and you should be good to go.

Out of stupid curiousity, but I'll check the amp install thread again... are you just shoving the wire down in the positive battery terminal with a bare lead? or are there some sort of spades or something that work well with battery terminals? I've yet to figure this part out haha.

 

one thing to be careful about - for the low-current remote wire, you need a
relay whose coil doesn't draw very much current - if your remote wire is
rated .11A = 110mA, you need a relay that draws less than that. On
Radio Shack's website, the 30A relay draws 160mA. You don't need 30A
for your fan, so I'd look for a smaller relay capable of handling a few amps,
but drawing well less than 100mA for the coil. Hope that made sense.

 

This thread has been very helpful. I've had a general understanding of relays, how they work, and what their applications are but never as in depth as this.

Thanks everyone!

 

alright thanks, ill check out radioshack because its closer to my house. i only plan to run at the most my fan and eventually some cold cathodes and neons, but they dont draw a lot of power.
Good advice!