Hey everyone,
A while back I bought this antique horn from a garage sale with the goal of fixing it up. It so happens to be the same colour as my car 
First off, I haven’t a clue where it’s from. It’s missing the back cover that would have had a metal plaque with the manufacturer’s name on it. There are no indications on it whatsoever, it doesn’t even have a negative wire.
My best guess is that it’s from the 1950s or earlier and initially made for a boat or a train.
Today, I took it apart and cleaned up practically everything using WD-40 and/or oven cleaner. Before the clean up, I hooked it up to a 9 volt battery and I heard a quiet click… barely audible.
Here’s the re-assembled horn after the clean up :
The back end before :
Front part of the speaker after a little sanding and a few drops of oven cleaner :
After clean up (I had to stop because I discovered 3 little holes <1mm in diameter) :
Shortly after beginning to clean up the back part of the speaker :
After :
After a bit of calibrating, I tried hooking the horn up to my half dead 36 volt bicycle battery pack.
I braced myself and…
the click was a little louder but it didn’t resemble anything like
a car, boat or train. The best I got was a quick series of clicks.
Afterwards, I hooked up a spare plug (OKAY I FEEL BAD ABOUT HAVING DONE THIS AND EVEN BEFORE DOING IT I KNEW IT WAS RISKY) to the positive and negative
terminals. I plugged the horn in, quickly tapped
the power switch and had a blue spark.
I decided to give up any further attempts at 120 volts, and to my
relief, when I returned to 36 volts, I had the same clicks as before.
Therefore, my horn is either still okay, or it was broken from the start.
Do any of you guys know where I could get this checked out or
how I could repair it?
Tomorrow morning, I’ll hook up my horn to my car and see what happens when I honk 
Hopefully it won’t be just clicks.
Back end (after cleaning up) :
