Truck Air Horns

Pembo, I have set up a few of these for mates, using what you said truck tank, el cheapo compressor. If you want the system to recharge automaticly, you'll need a hops switch(like on arb compressors) wired in before the relay for the compressor and a fuel shut off(to activate the horn), which you can get from any wrecker of a duel fuel car. they're not desighned for the pressure but I have no problems and they're dirt cheap. hope this helps.

Rob,
I agree with what Tuff60 has said. Another idea for the switch is to use the one from ARB which controls the diff lock/s (air solenoid?)

Yep, I set mine up with a 1/2 Gallon Truck air Tank, my Blue Tounge Compressor, and ARB pressure switch and an ARB 12V air Solinoid. Works awsome!
I don't know exactly how well I cheaper air compressor will go at an 80psi restart though. :-(

Rob,

I set up an agricultural chemical sprayer solenoid ($65) that handles 140 psi. I have a remote switch by the turbo timer behind the steering wheel so that the normal horn still works. The switch is a dash mounted horn switch that activates a relay via a fuse. The relay activates the solenoid (an electromagnet).
My horn is a train style horn. They usually need high pressure (at least 50 psi) but low flow. The air supply could come from a small a/c that has a tank like the ARB job etc. I have a modified air cond comp fitted with a 5 litre tank (a tank any bigger needs certification). The supply is via 6mm truck brake line (I cut into my pressure gauge / switching line. My compressor has the usual high and low pressure switches like the ARB job.
Horn sounding duration depends on tank capacity and compressor capacity. Obviously my 8 cfm compressor can sound the horn all day or until something rattles loose (it's loud enough to make a nearby doof doof car CD player skip, LOL).

Its good fun but you have to be responsible because it can scare people. Have fun.

Regards,

Chris.