Hello
I am a woodworking hobbyist and I recently built a VW bus bunk bed. I added a steering wheel, hub caps, emblem and non working headlights. I would like to wire a VW horn into the dash. I purchased the horn and a push button switch but need some guidance in the wiring. Can I use a 110ac to 12volt transformer and do I need to wire in a relay. Any advice is appreciated , thank you.

 

A transformer will work, but from what I found you will need one capable of producing five amps for the horn to work. A push button by itself should do the job, but in the interest of safety you will want it on the 12 volt side of things (little fingers get in the wrong places!!).

If you want to use the steering wheel button you will need the relay... if just a regular push button then no as long as it is rated for the job.

 

A transformer will work, but from what I found you will need one capable of producing five amps for the horn to work. A push button by itself should do the job, but in the interest of safety you will want it on the 12 volt side of things (little fingers get in the wrong places!!).

If you want to use the steering wheel button you will need the relay... if just a regular push button then no as long as it is rated for the job.

Ok thanks
the push button switch is rated for 5 amps. So I can wire the transformer to the switch then to the horn and it should work?

 

It should work. The main reason for the relay is your horn draws much more current than a relay. Since the circuit was designed with a relay in mind the wiring, contact area of the steering wheel clock spring, and such were sized for the load of the relay instead of the horn itself. It just made life easier back in the day.

 

A transformer will work,

While I've never tried it, will a 12VDC horn work on 12VAC? I ask due to how a horn is made with the internal contacts to make and break the circuit to move the diaphragm.

 

While I've never tried it, will a 12VDC horn work on 12VAC? I ask due to how a horn is made with the internal contacts to make and break the circuit to move the diaphragm.

Exactly my thoughts.

Could always add rectifier and a capacitor. Might have to oversize the transformer slightly to compensate for diode voltage drop, but then again maybe it won't matter.

 

I doubt a capacitor will be needed, just a full wave rectifier, use a 12vac secondary.
Max.

 

I doubt a capacitor will be needed, just a full wave rectifier, use a 12vac secondary.
Max.

So I need a transformer and a rectifier? Sorry I'm not super knowledgeable in this area

 

Check the current on a automotive battery to get an idea of the transformer capacity needed and diode specs.
Max.

 

Good new is it works, the bad news is its to loud. Can I wire in a resistor to dampen the horn?

 

Can you use any kind of muffle material to dampen it?
Max.

 

Can you use any kind of muffle material to dampen it?
Max.

I was thinking of building a small insulated box for the horn

 

I built a small box with horn screwed to outside and the business end pushed against insulation and the electrical connections on the outside, it works well. Assuming the horn doesn't heat up. True?

 

Should be OK, especially if the electro-magnetic end is in free air!
Max..