32 6volt horn not good with volt drop 12v to 6v

[Newc]

Horn doesn't do much with a volt drop in line. Really spins with full 12 volts tho. Answers?? Newc

[drolston]

What are you using to drop the voltage to the horn?

[sugarmaker]

Newc,
Mine works pretty good with the droping unit from Snyder's. I assume you have adjusted it with the screw on the back?
Regards,
Chris

[glennpm]

Hi,


I posted this a while back


"I converted to 12volt and looked into various options. I bought a resistor but
didn't like the idea of the heat from it although the horn isn't used that often
to really be a problem. I found the post below and added a shunt wire to my
horn which bypasses one of the horn coils, simple and reversible. It works
great.

https://www.fordbarn.com/forum/showp...3&postcount=13


"We have had good luck soldering a shunt wire across the two wires coming out of one of the fields in the horn. This basically puts that field out of service, allowing the horn's rpm level to stay the same other than double. Did mine quite some time ago still works fine."

[fortyonerag]

Sounds like what you used to reduce the voltage can't handle the high current the horns draw. You can use a resistor for voltage drop IF the current draw is fairly uniform when the horns run.

If you can determine the current draw of the horn at 6V, you can then select the correct resistor to give you a 6V drop before the horns.

As an EXAMPLE ONLY, say the horns draw 10A (careful, I draw this number from my backside)

RESISTOR SIZE: A resistor that drops 6V at this current will give you the inline voltage drop you need. Ohm's law says V=IR (6V=10 A X 0.6 Ohm) so a resistor of say 0.6 Ohm will give you the drop you want. Use your own numbers here.

RESISTOR POWER RATING: The resistor has to be rated to absorb the power of the voltage drop. One of Ohm's laws says P=IV (Power rating = 10Amp X 6Volts) so 60W of heat will be dissipated. It will get hot, so I'd go up to say 100W to play it safe.

So, if, and only if, your horns draw 10A at 6V, you need a 0.6 Ohm 100W resistor.

[rotorwrench]

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The rotating Klaxon style horns have easy access to their field coils. There is a procedure to rewind these coils for 12-volt use. A person needs to find a spool of the correct gauge coated magnet wire and practice up on soldering skills. Here is the link.
http://www.santaanitaas.org/wp-conte...ooguh-horn.pdf

[Charlie ny]

I've been running 12v thru my '32 horn for 2 1/2 yrs....lucky I guess....only short toots. Charlie ny

[Planojc]

Back in the day of working on analog meters we would make our own precision resistors with nichrome resistance wire. Come to find out nichrome wire is used with wire welders so I cut about a foot or so of it and began testing the sound on a 6V Model A horn at various lengths and resistance. The best original 6V sound was with a wire resistance of .8 Ohms. I wrapped the wire around some nylon all thread, with heat shrink and soldered bullet connectors on the ends. Still working great.

[A bones]

Hey rotorwrench - Thanks for that. I may use it.

Planojc - Mine may be different,but what length wire did you end with. Thanks

[Newc]

Thanks fellows: try some of these ideas. Newc

[cas3]

To rewire for 12 volts, you use exactly half the wire gauge, and twice the length of the original 6v winding.

[sshep]

Originally Posted by Charlie ny

I've been running 12v thru my '32 horn for 2 1/2 yrs....lucky I guess....only short toots. Charlie ny

Agreed Charlie. My Dad never changed a thing when running 12volts to 6volt horns. Just tested a couple of 6V Klaxon horns he left me with a 12v battery, no issues. The one I picked out to use on my 6 volt system still works fine after testing with 12v too.

[glennpm]

Running with 12 volts won't burn the horn wiring but it doesn't sound right since the motor is running twice as fast as it would with 6V.


All you need to do is solder a wire to bypass one of the coils. Simple change with no need of rewinding or resistors. See my post #4 above.

[cas3]

glenn is correct, they just dont have that real AHOOOGA sound on 12 volts. Its doulbe the rpm, but mainly I think they spin up to max RPM immediately and take away the lazy spin and correct sound. https://www.youtube.com/watch?v=KBmvQ9MpnqY

[cas3]

The black and silver one at .34 is an example of spinning up too fast, unlike the first one in the video that has nice tone. The black and silver is also a modern POS I believe. I have about 40 ahooga horns, always buy em when they are cheap. Hoarder I guess.