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12V to 6V for Klaxon Horn

capngrog

By capngrog
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capngrog 5,000+ Points

capngrog

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I have a nice old (c. 1930) Klaxon horn that is, of course, rated for 6V.  I've thought of using a standard ballast resistor to drop the voltage down to 6V, but wonder if that type of resistor would handle the horn's amperage requirements.  Of course, hitting the horn button is usually an event of only a few seconds' duration; however, there are times ...

 

Cheers,

Grog

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I usually sound my Klaxon 12C (motor driven) three or four times a year to be sure it is working.  The first time, when it hasn't been used for a while it draws 30 amps, the second time it drops to 20 amps.  It stays at 20 amps unless it has been unused for a long time.  I had the cover off about thirty years ago lubed and tuned it then and never have serviced or touched it since.  It has never failed when I needed it.

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capngrog 5,000+ Points

capngrog

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34 minutes ago, padgett said:

Can you measure the draw (amps) at 6v ? That would tell the size or the resistor needed in both watts and ohms.

 

I'll give it a try tomorrow.  I have a 6V system in my Crosley wagon, and I can use that battery.  I'll have to figger out how to use my multimeter in the amps mode.  I'm a bit at sea when it comes to electricity; however, I do know that "I don't want to get any (electricity) on me!"

 

Cheers,

Grog

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lump 10,000+ Points

lump

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When I was a teenager, my parents' daily driver was a 67 Impala convertible, and our old car was (now mine) 1923 Hupmobile touring car. Dad was always rooting through junk shops and hardware stores, and finding old car parts & accessories. I recall one time when he found a Klaxon horn in good shape. He merely put a 6V resistor in a line, grounded it to the radiator core support, and used that Klaxon as the only horn in our 67 Impala. We had a lot of fun with that over the years! 

 

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Fossil 25,000+ Points

Fossil

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This is what I'm running the factory horn with. It's not an ooga horn though. 

https://www.amazon.com/uxcell-Converter-Regulator-Waterproof-Transformer/dp/B01CUA4LQQ/ref=sr_1_5?dchild=1&keywords=12v+to+6v+converter&qid=1608180938&sr=8-5

If you have an old amp meter out of a garden tractor or car just hook it in series with the horn. If you lived closer I'd give you one. 

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capngrog 5,000+ Points

capngrog

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On 12/16/2020 at 9:01 PM, Akstraw said:

Mac’s Model A Parts carries a voltage reducer for exactly this application.  About thirty bucks.

 

 

I found three voltage reducers on the Mac's Model A site, but none of them mentioned use with a Klaxon-type horn.  There was one  with a 25 amp rating which should be enough to power the horn.

 

Is this the one you were thinking about?

 

https://www.macsautoparts.com/voltage-reducer-with-wiring-magnum-12-to-6-volt-25-amp-28-73930-1.html

 

Thanks for your help.

 

Cheers,

Grogh

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padgett 25,000+ Points

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Well there are amps and then there are amps. A motor draws the max current on startup and drops quickly. That is why bigger ones often have a starting capacitor to soften the inrush (got deeper than sane figuring out how to reliably start a 13k btu RV AC from a 2kW generator a few years ago. I need AC).

 

Am sure a 25A Chinese reducer is fine for electronics but not so about a motor.

 

The link to a not-so-cheap one above says it all "For Heater & Wiper Motors As Well".

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capngrog 5,000+ Points

capngrog

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Akstraw;

 

I did a search for "Mac's Model A Parts" and the more generic "Mac's Auto Parts" came up.  I searched that site and came up with the 25A voltage reducer shown in my above post.  I again searched "Mac's Auto Parts" with using the stock number shown in your recent post (A13802R) which yielded this:

 

https://ecklers.com.imgeng.in/media/catalog/product/6/4/64-73930.jpg

 

This is the one that came up in my previous search and has a sale price of $144.99.  Where did I go astray in my search for the voltage reducer you recommended?

 

I appreciate your help.

 

Cheers,

Grog

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capngrog 5,000+ Points

capngrog

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Jack M;

 

From your research, it looks like Summit has the same VR-10 25A voltage reducer as the one offered by Mac's Auto Parts.  It appears that the only difference is that Summit offers it for $122.45; whereas, Mac's Auto wants  $144.99.   A savings of $22.54 is pretty significant in my book.  It seems that Mac's Auto Parts is owned by the Eckler's group, whom I've found, in the past, to be a bit pricey.

 

Thanks for your help.

 

Cheers,

Grog

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JACK M 25,000+ Points

JACK M

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It looks like you can get something similar for a lot less money with a simple google search.

I have done many six to twelve conversions and don't recall any major problems. 

I wont try the Mopar fluid drive change over however.

But have done gauges, blower motors etc. and used twenty dollar reducers.

Oddly enough I am doing this exact thing with some old horns I dug up recently and think they will work with 12 volts, just louder.

I have a buddy that has the knack for making these things work so I am going to approach him after Christmas. If I need a resister I have one of those

$19 units from Speedway in my stash. 

 

Fun stuff....

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capngrog 5,000+ Points

capngrog

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You're right in that the 6V klaxon-type horns will work with 12 volts, because I've tried that with mine.  My main concern is that repeated/prolonged use of the horn using 12V could cause the motor to burn out.  Some of my friends have told me to just use the horn intermittently for short beeps.  Well, where's the fun in that?  If I can't use the horn to clear elephant herds from the right of way, what's the use?

 

Cheers,

Grog

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maok 5,000+ Points

maok

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Klaxon works fine on 12v, I've been doing it for 5years on our tours, however, it the sound is very high pitched and loud, so it doesnt quite sound correct, especially if you have an alternator installed (14v).

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Bloo 25,000+ Points

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Don't they make new 12 volt Ahoooga horns? If it has to be old, maybe one from a Dodge Brothers car?

 

If you must use this one, try the ballast resistor. Try a Chrysler one. It's about half an ohm. It might even work. There is no good way to do this with a resistor, as the load is not constant (it's super-high on startup). When you find a resistor that works, the horn will be starting on less voltage than intended, but running on higher voltage than intended. Is that good? Not really, but it might be OK. Reducing the run voltage all the way to the original 6 (or 7) will probably make the motor not start.

 

In my opinion trying to run a motor on an electronic "voltage reducer" is most likely going to result in a pile of broken voltage reducers.

.

Edited by Bloo (see edit history)
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lozrocks 1,000+ Points

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Your best bet is a 12volt to 6 volt step down converter that will supply 30 amps.

https://www.ebay.com/itm/New-Waterproof-DC-DC-Converter-Regulator-12V-24V-Step-Down-to-6V-30A-180W/141929142470?hash=item210ba2d8c6:g:IlsAAOSwz2pfQ05B

This will do the job.

There are 40 amp units available as well if you need more grunt.

 

Do not use a resistor. It just becomes a fire hazard.

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capngrog 5,000+ Points

capngrog

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On 12/23/2020 at 2:42 PM, Bloo said:

Don't they make new 12 volt Ahoooga horns? If it has to be old, maybe one from a Dodge Brothers car?

 

If you must use this one, try the ballast resistor. Try a Chrysler one. It's about half an ohm. It might even work. There is no good way to do this with a resistor, as the load is not constant (it's super-high on startup). When you find a resistor that works, the horn will be starting on less voltage than intended, but running on higher voltage than intended. Is that good? Not really, but it might be OK. Reducing the run voltage all the way to the original 6 (or 7) will probably make the motor not start.

 

In my opinion trying to run a motor on an electronic "voltage reducer" is most likely going to result in a pile of broken voltage reducers.

.

 

Yes, they make 12V Ahoooga horns, but they don't have the style and panache of an old original Klaxon.  The Klaxon I have is circa 1930.   and I don't want to take the chance of burning out the motor.  The car I plan to install it on is somewhat of a mixed anachronism (it's a 1952 Crosley pickup rat rod), but I install old, odd accessories whenever possible.  The Crosley rat rod ain't pretty, but it sure is interesting and lotsa fun. 

 

Merry Christmas,

Grog

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