The Ford Barn

Russ B · 02-25-2013, 11:55 PM

How to Restore Your Model A, Volume 8, pp.110-112, has a reprint of an article by Bob Hess on "Converting to 12 Volts." Part of the discussion is about modifications needed so one can reliably use their existing 6 volt horn. I would recommend that anyone planning a 6 to 12 volt conversion should look at this article.

As the reprint is from a 1991 original article, revised 2002, I found one additional update that is still needed.

Because of the heavy current draw of a horn, the author indicates a small resistor, sometimes used for dropping the voltage, does not work when converting a 6V horn for use with higher voltage. He recommended an Ohmite Divideohm part 210-100-1 RO. That part number no longer is current. Since it took a bit of searching to find the current part number and a source where I could buy it, I am posting the updated number for anyone who can use it.

The new Ohmite part number is D100K1ROE.

I found it at www.galco.com

the other side shows how it is adjusted, moving the slider bar in the middle:

The author also recommended adding a relay to the horn circuit as a means of getting a stronger current to the horn. I built a small test circuit, shown below, to be able to test and adjust the sound of my horn.

My horn still needs some adjusting as I put it together from several different, older (mostly aftermarket) horns and replacement parts. The little 2X3 board is just a simple mounting arrangement of the components of the circuit. Once I get it all adjusted, I will permanently mount the relay and resistor on the floor pan under the seat.

02-25-2013, 11:55 PM	#1
Russ B Senior Member Join Date: Aug 2011 Location: Millbrae, CA Posts: 508	6 to 12 V horn conversion How to Restore Your Model A, Volume 8, pp.110-112, has a reprint of an article by Bob Hess on "Converting to 12 Volts." Part of the discussion is about modifications needed so one can reliably use their existing 6 volt horn. I would recommend that anyone planning a 6 to 12 volt conversion should look at this article. As the reprint is from a 1991 original article, revised 2002, I found one additional update that is still needed. Because of the heavy current draw of a horn, the author indicates a small resistor, sometimes used for dropping the voltage, does not work when converting a 6V horn for use with higher voltage. He recommended an Ohmite Divideohm part 210-100-1 RO. That part number no longer is current. Since it took a bit of searching to find the current part number and a source where I could buy it, I am posting the updated number for anyone who can use it. The new Ohmite part number is D100K1ROE. I found it at www.galco.com the other side shows how it is adjusted, moving the slider bar in the middle: The author also recommended adding a relay to the horn circuit as a means of getting a stronger current to the horn. I built a small test circuit, shown below, to be able to test and adjust the sound of my horn. My horn still needs some adjusting as I put it together from several different, older (mostly aftermarket) horns and replacement parts. The little 2X3 board is just a simple mounting arrangement of the components of the circuit. Once I get it all adjusted, I will permanently mount the relay and resistor on the floor pan under the seat.