Hummer

I've got my amp in my back seat which looks cool, but doesn't cool very well. I bought 3 mini fans, about 1" square to cool it. Can I wire these to the remote turn on wire? I want them to come on whenever I turn my stereo on. What's best?

Jim85IROC

iTrader: (2)

The remote lead from your amp is only designed to provide about 0.5 amps, which is not enough for fans. You need to use that remote lead to turn on a relay that can provide a direct shot of 12 volts at up to 20 amps.

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Chris Luongo

Go to a car stereo shop, or AutoZone, or whereever....you want a standard SPDT (single-pole, double-throw) relay. Actually, a SPST (single-pole, single-throw) relay would work as well...but they're harder to find.

If the guy helping you has no clue what SPDT means...just ask him to show you what relays he has and you can pick for yourself.

The relay has five terminals:

85-coil
86-coil
30-common
87a- normally closed
87- normally open

Here's how to hook it up:

85: Hook up to ground
86: Hook up to your blue remote wire

(When the radio is on, 12V+ will be sent
to terminal 86, engergizing the relay's
electromagnetic coil.)

30: Hook to constant 12V+
87: Hook to the positive wire on your fan
87a: Don't connect to anything

(Also, don't forget to ground your fan
too.)


If you're curious how the relay works:

Normally, when the relay is "off," 30 and 87a are connected together.

When you supply power to 85 and 86, you are energizing the relay's electromagnetic switch, turning it "on."

When you do this, 30 becomes disconnected from 87a, and connects itself to 87, sending power to your fan.

The relay only draws something like .1 amp of current, which is easy for the remote wire coming from your car radio. Now, you can hook up practically all the fans you want (up to 30 amps' worth) to the relay.

Once you know the basics of how a relay works, you'll realize you can do nearly anything you want with it. You can turn current from negative to positive, you can make stuff turn on when you turn the switch off...you can do anything you can imagine with a simple relay.

Jim85IROC

iTrader: (2)

That SPDT relay that he mentioned above is known by most people as a "bosch" relay. It's your standard relay that comes with fog lights and all of that crap.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

Hummer

Thanks a lot guys. I've had relays explained to me a million times, but it really never clicked until now. All I knew is that they give you a boost when needed. It's nice to have an explanation like that. Anyways, thanks again.

Belker

[This message has been edited by Belker (edited June 06, 2001).]