# current draw of 12vdc air horn



## RustyShackleford (Jul 7, 2012)

Anybody have a clue as to how much current an automotive airhorn like this one:

http://www.amazon.com/gp/product/B001CS6C9M/ref=oh_details_o01_s00_i00

... would draw ?    The product description is of no help.    The meager instructions show a 30amp fuse, so I assume it's a lot of juice.   My multimeter only measures up to 10 amps so I'm afraid of blowing its fuse.

I'm not going to use it in a motor vehicle, so I'm a little perplexed as to how to power it.   

I'm actually going to use it to attempt to frighten away nuisance birds.   It's the last stop for them before Mr. 20 Gauge, so they'd appreciate your help !


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## basod (Jul 7, 2012)

If you plan on wiring it up you'll need a 12V battery parralleled with a charger. 

If you already have an air compressor you could just attach the horn to a valve and use it when needed.  A portable pancake compressor may be cheaper than battery/charger/wiring, plus you have it for filling tires, air nailers etc.  Most of them will run up to 120psi and that'll surely provide you with plenty of blasts before having to plug it in and re-pressurize.

A more portable option maybe one of those boat distress horns, and adding a refill valve that could be pumped with a bike pump.


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## MasterMech (Jul 7, 2012)

Wire it up like a regular automotive horn, with a relay that can handle 30 amps.

12V Mower battery should do nicely with a small solar charger attached.


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## RustyShackleford (Jul 9, 2012)

Thanks all. I figured an automotive battery is required; my girlfriend conveniently just need a new car battery so using her old one. Probably don't need to worry about charging it, because I will likely use it very little and only for another week or two with any luck - the birds go nuts during breeding season and attack their reflections in the windows - and I have a trickle charger I can top it off with when needed. Just curious how many amps, for wiring and such.

Using a compressor or non-electric version is no good, because I want to be able to operate it remotely - from a button next to my bed, which goes to the aforerecommended relay, conveniently supplied with the air horns linked above.


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## MasterMech (Jul 9, 2012)

RustyShackleford said:


> Using a compressor or non-electric version is no good, because I want to be able to operate it remotely - from a button next to my bed, which goes to the aforerecommended relay, conveniently supplied with the air horns linked above.


 
Gonna make a helluva alarm clock in the off season.


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## basod (Jul 11, 2012)

The 30 amp is probably for inrush current during starting.
10 gauge from + through 30a fuse to relay load contact and one straight back to the negative battery lead should work. You can use something around 18-22 (probably even less like 28 if you can find it) for the relay coil (A1-A2) You'll still need 2 legs for the remote switch as this isn't a grounded automotive system. A length of 2 conductor or some left over phone wire/t-stat wire would work fine for the relay load to switch. You can get those little inline glass fuse holders and put a low fuse rated ~1-2amps just to prevent a fire on the remote leg you're bringing into the bedroom.


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