I've been reading through some posts from others about time delay relays, but nothing jumps out at me and says, "YES! This is what you need!" So at the risk of sounding noobish, I thought I'd just come out and ask.

What I want to do:
My off road race truck has a dixie horn. It's become our trademark. Right now I have a regular switch that activates a relay, which powers the compressor for the air horn. I have to hold the button down while the horn plays. I'd like to convert the system so that I only have to press the button once to play the whole horn.

Requirements:
I'd like something simple (simple means less likely to break), and robust.
Must work with 12vdc @ 20 amps (if I'm replacing the existing relay, otherwise, I guess I just need enough to trigger that relay)
Single trigger to activate, and stays on for a set period of time from the initial trigger (not from when the trigger is released)
Adjustable length (I'm not sure exactly how long the horn loop is, so I want to be able to fine tune it)

So I ran across one of these: http://www.grainger.com/Grainger/DAYTON-Time-Delay-Relay-5WML9

Seems like it might do the trick, but since I really have no idea what I'm doing here, I thought I'd ask some experts to point me in the right direction.

Thank you in advance.

 

Automotive mods aren't allowed to be discussed on this site, but since it's for an 'offroad' vehicle I'll take the liberty of chiming in. If the mods decide to close the thread, they can delete this post too, if they feel like it.

no, the relay you linked to won't work. it's for 24VAC/DC. You need 12V. All the relays I can find at grainger that would work are pretty expensive.

much more affordable products are available on ebay but probably won't handle a 20A load. Simple solution, use the ebay timer relay to switch a high amp automotive relay to switch the compressor.