The Stovebolt Site Forums The Shop Area The Electrical Bay Horn Capacitor

Hi everybody, the capacitor in the horn for my 52 is shot. I have checked with Radio Shack, and the two local parts houses. They didn't have anything close. I checked online as well, and I don't want to buy a gross to get a single part. So could anyone tell me where they got the capacitor to repair their horn? I would really appreciate it, Jimmie.

Jimmie D,

I had no idea there was a capacitor inside one of these old horns. I wonder what its purpose is? Have you tried a local electronic repair shop...maybe something along the lines of TV or stereo repair. Maybe replacing the horn would be the best alternative. Good luck.

Stuart

Stuart,
I did try the electronic repair shops here, with no luck. Some people call it a capacitor, some call it a resistor. In the trumpet style horn the original part looks like layers of foil and paper rolled around a tar like plug in the center. I have been told that it is to keep the points in the horn from burning out. I have working ramshorn horns in the truck, I just thought it would fun to have one of the original style horns under the hood. Jimmie.

Jimmie D,

I use deals called MOV's at work when I need to quench an arc at a contact. They are 'metal oxide varistors' and are wired in parallel with the contacts. I wonder if Radio Shack might have these items. Maybe it takes a special deal on the contacts in a horn...don't they open and close a bazillion times a minute to make the TOOT!

Stuart

I didn't know they used a capacitor either, but since the horn coil is a reactive device, it makes sence to use a capacitor with it. I would expect it to work pretty much as the engine coil and condenser(which is a capacitor). I would suggest trying an automotive condenser as an experiment just to see if the horn works. Such experimention will not damage the horn.
meansam

The condenser is a capacitor. Used to smooth out the peaks/valleys in the DC power supply.

Radio shack sells capacitors in a variety of sizes, however if you cant find one there, try digikey.com, or newark.com.

MOV's are generally used to protect a circuit from over-voltage such as lightning strikes and errant alternators.

Scott

I wonder if swapping to 12 volt would hurt the horn if you only used it to wake up those knucklehead on their cell phones at the stoplight. If so then a resistor might be used to drop the voltage.

Scott,

Regarding MOV's..I was under the impression that when a set of contacts was opened under load, voltage would spike. The MOV absorbed this spike and saved the delicate contact surfaces. Isn't this how they work? Much the same as a condenser in a points type ignition.

Stuart

If the capacitor is making it not work that probably means it shorted. The horn would probably work a little while without one at all.

I don't think the actual value is real critical since the intent is just to suppress arcing. I'd buy an assortment at Radio Shack and experiment if it were me.

But then my electronics training dates from the days when vacuum tubes were common, and its not been kept up to date...

Tubes still make the best Audio amplifiers....LOL

Hey, everybody. Thanks for the great information. In the archives there is mention of a 100 volt 56 microfarad capacitor to replace the shorted out original. Any ideas or opinions on that? Any ideas or tips on installation? I can solder in a new part, but electricty just escapes me. It just will do things that my literal mind says it can't/shouldn't do. Jimmie.

This is the source I use for buying capacitors.
http://www.justradios.com/

They have a great site with charts and prices. They will usually mail the next day.

Digi-Key is good too but I think you would need one of their catalogs first.

56 Microfarad is an odd value, closest you'll find is going to be a 47 microfarad (notated uF). Radio Crack isn't going to have any capacitors of this value, but PM me your address and I'll mail you a cap.

I'm sure the cap is for arc suppression but does anyone have a schematic for these original 30's-50's style horns? That should clear up what it's purpose was and how it is applied to the circuit.
Denny Graham
Sandwich, IL

Some of the guys might not be familiar with what we are talking about so I thought a picture from when I rebuilt mine might help clear things up.
http://rides.webshots.com/photo/2618841590098611668vIAlyJ
Denny Graham
Sandwich, IL

you could use one from a distributor.

Hi All,
I just wanted to thank everybody for their help. I want to thank Justin for the assortment of capacitors. As soon as I get a chance to work on the horn I will post what I find out.

Reviving an old thread I know but wondering if a suitable capacitor was found and if so any details?

Cheers,
Dave