Horn for my tractor

Hello all,
This is a simple question and I know someone will have the answer even if it a bit off topic. I have a 755 John Deere and want to install a
horn on it. The tractor has a 12 volt system and the horn is 6 volt. Can't a resistor be added to make the horn work. I assume a resistor of the same value as the horn is added but in series or parallel??? Or as I wrong.
TIA,
Rich
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You can indeed add a resistor, in series. They sell 12V horns, though, it could be easier. I have a 12V horn on my boat.
i
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Thanks, you are right about a 12 volt horn but this horn came off a '32 Ford and according to my neighbor who owned the Ford its been sitting for 65 years under his bench. I wanted to give it a chance at a new life:) It seems someone hit the car when it was parked and it was totaled, the horn is all that remains.
Rich
Ignoramus4093 wrote:

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It seems to me this could very likely be a motor-driven horn. If it is it would be hard to measure it's resistance, also running it at a different voltage would change it's sound and maybe overload it. For something like this I've salvaged a length of nichrome resistance wire from an old heating element. With one end of the wire connected to a 12 v battery and the horn grounded to the other battery terminal I connect an alligator clip to the horn wire and to the other end of the resistance wire. With a voltmeter across the horn I move the clip toward the other end until I get a 6v reading.Without a voltmeter you could just go by the sound of the horn. When I determine the proper wire length I wind it around a piece of somesort of non-combustable building board and connect it in series with the horn circuit. Engineman1
dogpoint wrote:

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dogpoint wrote:

Sell the horn on ebay. It'll go on to grace a _real_ '32 Ford and will feel like it's where it belongs. You can use the money to buy 10 (or 100?) horns at your local parts emporium for a truely interesting sounding tractor.
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dogpoint wrote:

It would be best to use high current (e.g. 22 amp) or more rectifiers - 10 in series to drop the voltage. That would be better than a resistor for the real sound. The impulse voltage/current would be lost - e.g. no punch and it would sound funny as the resistor heated up and changed the current.
It would be better to have a 6 volt battery to be the other 6 volts. A motorcycle battery - but then how to charge it....
Not always easy.
Martin
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motorcycle
Straight from the 12 volt system. Connect both negative terminals together, connect the 6 volt terminal to the 12 volt terminal via a high value resistor. Something like 6k9 ohms will give about 1 milliamp charging current, a slow tricke which would give a nice slow charge that will allow you to use the horn a number of times until the bike battery discharges and then it will take a couple of days for the bike battery to recharge from the car battery. If you wanted a faster recharge, decreaase the resistor value to around 1k ohm and this will increase the charging current to about 7 milliamps.
I charge the second (12 volt) battery in my car via an old coil resistor and this allows a charge current of a few amps with no melting if there is a short on the second battery wiring. A resistor is added to disconnect the second battery when the moptor stops and only draws current when the motor is running.
Hope this helps, Peter
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dogpoint wrote:

A new 12V horn is $10, a used one $2 Horns pull a lot of current. A resistor to do the job may cost you as much as a horn. Is this some sort of special horn?
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I have changed several VW's from 6 volt to 12 volt and I have never bothered to change the original 6 volt horn as they are quite happy on 12 volts, and give a little bit more noise. Mind you, I have never tried to see how long the horn would blow for, but they certainly lasted long enough to give a good blast without getting hot. Some of them even had an adjustment nut to allow you to get a slightly different note.
You are correct about a resistor, in series, which would reduce the current flowing and cause a portion of the voltage to be across the horn and the other part across the resistor. To get a suitable cheap resistor you could use a couple of old car (points ignition type) coil resistors, in parallel and then wire this assembly in series with the horn, but I wouldn't bother with the extra trouble. The resistors would get hot in use.
Hope this helps, Peter
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    --Here ya go, bwahahaha!     http://www.dieselairhorns.com/trucks.html
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"dogpoint" clip) Can't a resistor be added to make the horn work. I assume a resistor of the same value as the horn is added but in series or parallel??? (clip) ^^^^^^^^^^^^^^^^ I take it you are doing this for the fun of it. The resistor would have to be in SERIES. But, for extra fun, why not wire a red light in series with the horn (has to be a six-volt bulb of similar current drain) so when you blow the horn, the red light turns on?
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But, for extra fun, why not wire a red light in series with

Red light turn on, blowing, extra fun.
What is this NG devolving into?
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Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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Leo Lichtman wrote:

If it isn't your vehicle, wiring the horn to the brake light switch is always fun.
Chris
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Christopher Tidy wrote:

Or the low beams, turn signal, etc.
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In article

Actually I would recommend a 12 volt headlight (you probably need 2 in parallel) because a surge will kill the 6 volt light too quick and a 12 volt light array will nicely limit current at 6 volts.
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Test it out in series with a 6v headlamp
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If this is a motor-driven klaxon type horn, the headlamp idea is going to limit the current too much. You would need a resistor of just a couple ohms but very high wattage (say 50W). Those 6V motor horns draw from 8 to 12 amps from 6V, depending on size. You don't want to run a 6V motor horn at 12V, it will turn the motor too fast for the horn to resonate properly and it will start releasing its smoke after a few seconds of testing. What worked for Peter's old VW buzzer horns will kill a motor horn.
If the horn is a vibrator/buzzer type, it will take more abuse but a resistor is still recommended if you want it to last. The buzzer horns draw nearly as much current as the motor type, so you're still talking about high-power resistor. You should probably experiment for the resistor value, don't just match the DC resistance of the buzzer coil (quite low) because these buzzer horns operate by periodically interrupting the current to the horn, thus the actual impedance of the horn while blowing is an AC one, primarily inductance. Your current-limiting resistor value will end up being a much higher ohm value than the DC resistance of the horn's magnet.
Good luck,
Adam
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The 6V headlamp in series will probably be the safest (for the antique horn). It would most likely pass enough current, while acting as a voltage divider sharing half of the applied 12VDC.
A small 6V lamp would likely limit the current, and the horn may not run or not sound like it should (loud). Lamps are handy to use at other times, as current limiters.. light emitting power resistors.
I would feel exceptionally lucky to be given a Ford Model A horn.. not just for the dollar value.
Auto parts stores used to have a device for using 6V accessories with 12V systems. It was a sort-of transition product, commonly available in the mid 60s when there were still a lot of 6V aftermarket parts around (as well as earlier cars with 6V systems that were being converted to 12V). Lamps were easy enough to change, but electric wipers, heater blower, etc could be used with 12V batteries.
The ones I used to see were ceramic blocks with a semi-circle of heavy duty coiled resistance wire in a trough. A brass screw terminal at each end so it could be placed in say for example, the heater/defroster fan motor circuit for use with a 12V battery system. A little open U clamp with a thumbscrew let ya clamp it in place (typically under the dash).
WB ...........

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Some older tractors used a ceramic resistor to limit the 12v from the tractor to 6v at the coil. International and Fords come to mind. Check out Tractor Supply Co. or even a NAPA dealer. I even think some Chrysler products from the 60's used them. Jesse
dogpoint wrote:

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If you can find the jumper bar in your battery you can tap off 6V in the middle of the battery. I've done this in the past for old hotrods. Usually scraped the top of the battery to find the jumper and then tapped into it and covered the tap with roofing tar. lg no neat sig line

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