MTFCA Forum

So I found a repro horn at Luray and tried jumping it off my battery. and It's not working. Do they sell a new circuitboard for these? Everything inside look new. No signs of water or corrosion.

Do you have a picture of the horn, or the name of it? The original horns don't have a circuit board. There are two types of electric horn original to a T. One is a magneto horn and the other is a battery horn. They are not interchangeable. The magneto horn can be used on any model T if it is connected to the magneto, but it won't work on the battery and the battery horn will not work on a magneto. These horns are made to be used with a 6 volt battery. It might not work with a 12 volt battery. There are also OOGA horns which were not original to the T, but were stock on a Model A. Most A horns were Spartan horns. There have been many reproductions of the OOGA horns and some might have been made for 12 volts because they are used on later cars. All of this type have a small electric motor and the commutater and brushes must be clean for the horn to work. There is also an adjustment which if too tight or too loose will either cause the armature to stick or to spin without honking the horn.
Norm

So I was able to take some pictures. I could only see writing on the circuitboard. I couldn't find anything on the body of the horn. I never knew that this may only be able to run on the Mag. That could be.

This is what the guts look like

That appears to be a "Fun Projects" reproduction horn with a '26 - '27 mount - maybe John will respond.

I agree with Steve, Based on the mount it looks like a 26/7 horn and judging from the base, where the circuit board is, its to large to be a mag horn. I believe that the adjustment may be the brass nut with the slotted bolt for a flat head screwdriver. Simply connect the horn and tighten or loosen the nut to increase or decrease the space between the contact or points, if you will, so the magnet will engage causing the rectangular spring metal plates will vibrate resulting in a sound. That’s if you’ve looked down the bell and didn’t see a flat blade screw or perhaps Philips head or it could even be a nut to tighten or loosen the diaphragm for a different pitch. I see pop rivets on the support plate. So it very well could be the brass nut and slotted bolt. Just another question is there one wire or bolt to connect the positive wire? If so how did you you ground it? If there are two wires or connectors did you hook both positive & negative up? Just using Ockham’s razor, "the simplest explanation is usually the best one.", to explain why it’s not working.

Yes it has one wire connection for the positive. I used a jumper wire from that to the positive of a 6 volt battery and then another jumper wire from the bracket to the neg post. It may be that the plate is too tight like you said.

Wast that horn offered in 12v also??

I think it was made for a 12 volt as well. But everything i've read says if you hook it up to a 12 volt and it's a 6 you will destroy the horn. I also looked down the throat and did not see any screw just the metal part that would vibrate. The other issue I have is the battery I'm testing it on is over 4 years old and has been sitting on a battery tender all that time.

Did you try adjusting the brass adjusting screw in the center of the diaphragm? I think that is what that screw is for, if I'm not mistaken.

I have a 1926 battery horn and a magneto horn, neither installed at this point. The mounting bracket looks like 26-27. The wide cover looks like my battery horn. The magneto horn would have a narrower dome cover than this one. The large coil in the middle in highest probability is an electromagnet not a transformer. Transformers only work with A/C (magneto), not D/C. You can test the coil to see if there is an open, preventing it from operating. But if the ICs are burned out and you cannot get a replacement circuit, then consider getting mechanical components from a donor horn. Radio Shack in the 70s had electronic learning kits that taught you how to make an oscillator circuit, keeping the coil. I'm sure youtube can help if you feel like pursuing that endeavor.

Thanks everyone. I also tried to look up the number on the circuitboard but couldn't find anything. I'm going to try adjusting the brass nut to see if I can get it to go. It is for a 26/7.

That horn could be 6 or 12 v negative ground as both were made by Fun Projects. Bird haven now makes these and you could contact them for repair.

Reading the pdf Instructions on their page tells to not connect other than neg ground or damage will occur to the electronic driver, also the powder coated unit is grounded by the bracket, there must be hard contact with star washers to cut to clean metal, same with the cover, it won’t operate with the cover off.

Bird haven (Texas T) same company, link to horn, contact Birdhaven
http://www.texastparts.com/mm5/merchant ... ns-Signals

I may give them a call. I read their PDFs as well thanks!!

Why not find an original? They are not hard to find. That might correct your circuit board problem!

DO NOT ADJUST THE CENTER NUT since it is setup once and no adjustment is ever needed unless someone else screwed with it. In that case you will likely damage the horn before you ever GUESS at the correct setting. When I owned Fun Projects I would let anyone return either version of the horn
(6V or 12V) and I would change it to the other 12 or 6 and only charged for the shipping. That would be for a horn not screwed with first. Send me an email BEFORE you start screwing with it since you will only make matters worse. The adjustments have to be made correctly in the correct sequence to get it to work right. The horn has a stainless steel diaphragm so it won't rust out. Finish is powder coated so it should hold up a long time.