Tractor Horn

[Dave Westlund]

I'm converting an M Farmall to 12v system and this tractor has a vey old horn on it (see picture) The tractor did have a non working charging system with a 12V battery in it when I bought the tractor and the horn did work but I only tried once for fear of melting the internals.

Would you recommend adding a resister in between the horn button and horn or is it not necessary?

 

[Texasmark]

Think VIT......Voltage applied x Current flowing x Time of occurrence. VIT= watt-seconds much different from removing the seconds and replacing with continuous. The thing going for you is that most of the time the horn is only blown for a second or two. One second of overpowering vs continuous overpowering are two entirely different situations. I'd do it and just keep the blowing periods brief.

 

[PJH]

I'm converting an M Farmall to 12v system and this tractor has a vey old horn on it (see picture) The tractor did have a non working charging system with a 12V battery in it when I bought the tractor and the horn did work but I only tried once for fear of melting the internals.

Would you recommend adding a resister in between the horn button and horn or is it not necessary?

I would use a relay in the circuit. The horn button would control the relay and the relay would do the hard work. The little "ice cube" relays are cheap.

 

[Dave Westlund]

Thanks for the replies!

PHJ Sir. If I use a relay I would assume that I would need a socket for the relay. I've never used one!

 

[Brown David]

Thanks for the replies!

PHJ Sir. If I use a relay I would assume that I would need a socket for the relay. I've never used one!

I've wired in many relays using individual wires with crimp on ends with no problems.

 

[NDIHC]

Ive had the ahoooga horn from my grandpa's 1927 Studebaker in my 56 chevy pickup since I bought the pickup in 1987. My brother had it in his 55 chevy pickup before that. Been running on 12 volts all those years. Just don't lay on the horn for more than a couple of seconds at a time. If you have any worries, a resistor could be added. Just have to make sure it's rated for at least whatever amperage the horn draws.

 

[used red MN]

The suggestion of using the “cube” relay will offer zero additional protection against your concern of feeding to much voltage to the horn. The same voltage that goes in a relay comes out of it. A relay is really just a remote switch. The wire you energize to activate the relay is telling an electro magnet to essentially “flip the switch or push the button in this case” In fact in a minute way it may actually increase the voltage due to the distance the current is traveling in wiring will be reduced. Likely the horn is powered right off the battery. Here would be my short cut approach. Temporarily feed the horn off the ignition switch, this will allow you to read the amps it takes on the ammeter. See how this compares to how much just the ignition coil alone deflects it which should be about 2 -3 amps. If this is comparable to the horn you could simply buy an ignition resistor to place in line to the horn feed. I believe those horns actually have a motor in them so it will likely draw more than the coil. In which case I would put a pair of the ignition resistors connected in a parallel in the feed. Parallel means you would put the 1st one
in the feed wire then you would run short jumpers off both terminals of the 1st one connecting to the terminals of the 2nd one, each jumping over to the respective ends. If I really applied myself I could probably come up with the proper ohm resistance if you gave the amp reading shown on the gauge.

 

[PJH]

Thanks for the replies!

PHJ Sir. If I use a relay I would assume that I would need a socket for the relay. I've never used one!

The "ice cube" relays have a mounting tab so it can be solidly bolted down. Then like David said, crimp connectors for the electrical connections. If you're concerned about the horn being 6 volt on a 12 volt system, you could add a heavy resistor in the circuit as others have said. I've used 6 volt horns on 12 volts with no problems but I'm a horn tooter and not a horn blower. Everything has a duty cycle.