Thread: car horn help!

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soooo I bought a cheap car horn from harbor freight about a week ago. My thought was to hook it up behind a fake car front that I have built with headlights attached. The problem is I cannot find a 12v power supply that will actually power the horn. I wanted to hook this into a picoboo 103 and just have a mat trigger that would make the lights and horn both come on at the same time.

http://www.harborfreight.com/12-volt...orn-40134.html

That is a link to the horn I bought, any help is greatly appreciated!

The .pdf specs lists the power draw as 10 watts, which would be less than 1 amp. As long as you find a power supply that is rated for 1 amp or better you should be OK. A PC power supply should work fine, too.

The supply I have is a 12v 1.5amp supply and I get nothing from the horn whenever it is hooked up to it, any ideas? The power supply works, I tested it with my picoboo and it works fine.

While I'm waiting on an answer to that question, just thought I'd post a video of what I came up with. I hooked the horn up to a 12v battery for this test, it isn't ideal but it worked. The lights are recessed can lights I found at goodwill last week for 3 bucks. The rest of the front is foam board and some paint, and I made a Doom Buggy license plate, naturally.

Originally Posted by vtswordfish

soooo I bought a cheap car horn from harbor freight about a week ago. My thought was to hook it up behind a fake car front that I have built with headlights attached. The problem is I cannot find a 12v power supply that will actually power the horn. I wanted to hook this into a picoboo 103 and just have a mat trigger that would make the lights and horn both come on at the same time.

http://www.harborfreight.com/12-volt...orn-40134.html

That is a link to the horn I bought, any help is greatly appreciated!

Do you have a old printer you're not using, if so most printer have at least a 1 amp DC power supply. One other thing, if you are using DC on the lights, and the horn, and your only requirement is for both to turn on at the same time. Then I would save the Picboo for something else (never mind I just looked at your vid and see why you need the picoboo). Your switch mat should be able to turn both on at the same time. Just a thought.

Go to your local thrift store and you should be able to find a wall wart (power supply) with enough amps to run your horn.

I wished the lights were DC as well would've made wiring a lot easier! If I can find a wallwart that will run the horn I might just buy one of those remote control outlets and run it from that to save my picoboo for something else. I unfortunately just threw out my old printer a few weeks ago, go figure...I left it sitting around for a while thinking I might use it for something :-p Oh well!

Worse case, use the battery (or battery charger)....it makes the horn loud. My wife was walking by when I played the video and she jumped I'm sure that is the reaction you want and I'm also sure you'll get that same react just about every time this prop goes off.

Horns require a good ground. I had a bad ground on old car once... Car horns are usually on a 15 amp fuse inside the car. I don't think you have enough amps to power it up.

The power supply you mentioned @ 1.5 amps should power the horn. When you energize it can you hear the relay click? You will need 12Volts to the coil to close the relay and 12 Volts across the Common + Normal open contacts to pass power on to the horn itself. Is this how you have it hooked up?

Correction: the positive lead will go through the relay contacts and the other side of the horn will go to ground.

I just checked the installation manual for that horn. It requires a 30 amp 12 volt power source to run the air compressor. A car battery or a large battery charger would probably be your best bet.