View Full Version : 12 Volt Issue

10-07-2009, 08:35 PM
I may be WAY off here, but shouldn't I be able to operate a car horn on AC power with a 12 volt DC power supply? Just a standard 12 VDC "wall wart" should work, shouldn't it? I've used them to power car stereos before, but I just can't get one to work with a car horn. I know the horn works, because I tested it with a car battery.

Any help is appreciated. Thanks!

10-07-2009, 08:43 PM
Same problem!!!!

10-07-2009, 08:43 PM
Action, it takes more power to activate a horn than a radio. Thats why it wont work. not enough output in the adapter.

Haunted Illinois
10-07-2009, 08:46 PM
Nope. Most likely, your "wall wort" is putting out less than 1 amp. A standard car horn needs from 5-6 amps. If you want to try to operate one, I would use a standard car battery or a battery charger that has a rating higher than 6 Amps.

10-07-2009, 08:52 PM
We use an airhorn from a truck and put it on a 24v solenoid. It works great.

10-08-2009, 03:54 AM
A computer power supply may have enough amps. Just check the diagram on top.

Cheap, too.

Jim Warfield
10-08-2009, 11:02 AM
The more "Juice" gets eaten by the wire, the more current you need to supply the item.
I couldn't believe it once when an electrician didn't know why his air compressor wouldn't run at the end of 250 foot of drop cord!?
One October someone forgot to get power run down the pole to power the Fire Dept. food tent across the parking lot from my house, at the same time a guy had set up a inflateable Laser tag thing in the other parking lot on the east side of my house and they ALL thought I could just be a good neighbor and throw them a drop cord to make their cookers, cofe makers, fans, battery chargers, lights all work.
Of course my electrical panel might have blew off the wall or killed something and I would get blamed because it was my cord/electricity..
Then some Chamber of Commerce planners thought they could run an entire Mayfest festival from one streetlight in the city park! Lucky an electrician was there to educate them on that.
(Disclaimer: I don't "Know" everything, but I know this much)

10-08-2009, 12:15 PM
Thanks, everyone for the input. I tried the computer PSU, but I can't get it to turn on. It's something in the lead that goes to the power switch on the computer or a "sense" wire? I don't know. I'm going to tinker around with that some more tonight. Also, I was trying the 12V adapter to run a dual tone horn, so I may try disconnecting one of them and see if that works.

10-08-2009, 08:42 PM
I got it figured out. Had the sense wire connected to the wrong lead. Works like a charm now. It says on the top that, for 12V, it only puts out 1.5 amps, but I bundled all 5 of the 12V leads together, so maybe it's 1.5 amps per lead? Would that be 7.5 amps? Haha, I'm just happy that it works and that it's LOUD!

Nick, if you have a power supply out of an old computer laying around, shoot me an e-mail and I'll tell you how I did it.

Thanks again, everyone

10-09-2009, 08:48 PM
Glad you got it working. I just logged on to send you a couple of tutorials on how to make these things work. They are a little tricky but work great because they have multiple voltages and lots of amps. Cheap, too.

Heere's a site with a simple way of using a computer power supply to power a variety of things: http://www.scary-terry.com/atxps/atxps.htm