Air horn, Pushing-my-luck wiring ?

[RatLabGuy]

Wiring in a nice HF 130dB air horn ;-)
On side of the small compressor that came w/ it, says 12v 40A. Holy hell that's alot of juice.
1 - I assume w/ that kind of current draw, best needs a line straight from battery on dedicated circuit 9fused of course) vs just tapping the main primary line at, say, the terminal block?
2 - In classic form I lost the relay that came w/ it. Have another rated 30A. Think it's really fry the relay to use that?
3 - I'm assuming at that kind of dB, mounting under the hood (say on top of fender) will be just as loud as outside...

 

[Roughshod]

1- Yes, go to the battery via a fuse.
2- A 30A relay should be fine for that application, at least for a while. After all, it's not like it is going to see a whole ton of use. How often do you really blow air horns?
3- Well, technically no, but it's certainly going to be good enough.

 

[Ron]

yea yea...time current curves etc....you will be fine..

THE HF air horn will burn up before the relay does.

I also bet if you read teh fine print you will learn that tehe 130dB rating is at 40A and you will probably never be ablee to get the horn to draw 40A....just my HF experience.

 

[Lurch830]

#2 - Radioshack sells a 12VDC/40A SPST Relay for $7....if you're that worried about it

 

[Benjie]

A ford starter solenoid is cheap as well. about $10 from any part store. Not sure the rating, but they can handle the juice.

 

[Reid]

maryland drivers that bad?

 

[Bobby D.]

Where did you get your horn from?

 

[RatLabGuy]

#2 - Radioshack sells a 12VDC/40A SPST Relay for $7....if you're that worried about it

Well I found the 40A one about 90 sec after posting this. Classic.

maryland drivers that bad?

Yep.
But 4x4Cross spectators are even worse

yea yea...time current curves etc....you will be fine..
THE HF air horn will burn up before the relay does.
I also bet if you read teh fine print you will learn that tehe 130dB rating is at 40A and you will probably never be ablee to get the horn to draw 40A....just my HF experience.

This thing is literally a small compressor, with a tube going out of it to the horn (which is just a big pice of plastic with the right dimensions to create loud noise). I'm not sure how it could "fail" besides the pump just no really cranking the CFM it's supposed to (which is likely I'm sure).

Where did you get your horn from?

Harbor Freight, on sale maybe $20. "kit" includes compressor, 2 horns, a relay, some tubing, and a few F quality bolts wit hwhich to mount it.

Not having ever used one - does it just run/crank out the noise as long as the voltage is applied? E.g. as long as you on the momentary switch? Or do they tend to just run out of air/pressure within about 1 second?

 

[catfishblues]

It's going to be a vane-style compressor, probably. It'll run as long as it needs to. It will create a short delay between the time you hit the button and when it builds the pressure to blow, but after that, it'll just keep honking.