The Ford Barn

Juergen · 01-05-2015, 05:33 PM

Anyone know the capacitance in the early Ford horns?

gearhead1952 · 01-05-2015, 11:23 PM

I was thinking they were just a coil of wire like most horns so maybe resistance or inductance values instead of capacitance?

koates · 01-05-2015, 11:30 PM

Hi there, capacitor value for early ford vibrator horns is .2uf (microfarads). Voltage rating 400 to 600 volts. They are available from electronics stores or easier to buy on ebay. Just google "capacitors .2uf " and scroll away. They are very cheap. Regards, Kevin.

koates · 01-06-2015, 01:12 AM

Further to the above. The function of the horn condenser is to absorb the arc or greater part of it across the contacts as they are opening. If the condenser is defective (which most are after 80 years of use ) the arc across the contacts will be very severe when the horn is operated. Contact life will be shortened and the horn will sound quite rough in its tone. A new condenser of .2 mfd (microfarads) and a quick reface of the contacts and final adjustment will give it a nice new sound. Regards, Kevin.

Juergen · 01-06-2015, 09:15 AM

Thanks, Kevin. That is what I needed.

I am repairing a horn and the vibrator just went down and did not return when the contacts opened up. I disconnected the top contact and it still went down (that is the coil stayed energized) so the coil must be getting energized through another circuit. I then took an ohmmeter across the capacitor and it immediately went to near zero ohms instead of going slowly there. So I cut the coil wire and the horn worked well, implying the capacitor was shorted. But I was afraid of short point life without the capacitor/condenser

And Gearhead1952 thanks for responding also. The later horns (I think after 1940) used the wound resistor instead of the failure prone capacitor so your comment is correct for the later style. I was going to substitute with one of those motors if I couldn't get the original to work.

rotorwrench · 01-06-2015, 02:48 PM

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Most of the early cars that didn't have a horn relay had a capacitor. The capacitor also helps get the vibrator function going with its stored charge as well as limiting the arcing of the points. They will function without a cap but will function a lot better with one. Using a proper relay will get more power direct to a horn than the old design circuits will if properly taylored to the application.

01-05-2015, 05:33 PM	#1
Juergen Senior Member Join Date: May 2010 Posts: 500	Capacitance for Ford horns Anyone know the capacitance in the early Ford horns?

01-05-2015, 11:23 PM	#2
gearhead1952 Senior Member Join Date: May 2010 Location: Julesburg, Colorado Posts: 714	Re: Capacitance for Ford horns I was thinking they were just a coil of wire like most horns so maybe resistance or inductance values instead of capacitance?

01-05-2015, 11:30 PM	#3
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,079	Re: Capacitance for Ford horns Hi there, capacitor value for early ford vibrator horns is .2uf (microfarads). Voltage rating 400 to 600 volts. They are available from electronics stores or easier to buy on ebay. Just google "capacitors .2uf " and scroll away. They are very cheap. Regards, Kevin.

01-06-2015, 01:12 AM	#4
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,079	Re: Capacitance for Ford horns Further to the above. The function of the horn condenser is to absorb the arc or greater part of it across the contacts as they are opening. If the condenser is defective (which most are after 80 years of use ) the arc across the contacts will be very severe when the horn is operated. Contact life will be shortened and the horn will sound quite rough in its tone. A new condenser of .2 mfd (microfarads) and a quick reface of the contacts and final adjustment will give it a nice new sound. Regards, Kevin.

01-06-2015, 09:15 AM	#5
Juergen Senior Member Join Date: May 2010 Posts: 500	Re: Capacitance for Ford horns Thanks, Kevin. That is what I needed. I am repairing a horn and the vibrator just went down and did not return when the contacts opened up. I disconnected the top contact and it still went down (that is the coil stayed energized) so the coil must be getting energized through another circuit. I then took an ohmmeter across the capacitor and it immediately went to near zero ohms instead of going slowly there. So I cut the coil wire and the horn worked well, implying the capacitor was shorted. But I was afraid of short point life without the capacitor/condenser And Gearhead1952 thanks for responding also. The later horns (I think after 1940) used the wound resistor instead of the failure prone capacitor so your comment is correct for the later style. I was going to substitute with one of those motors if I couldn't get the original to work.

01-06-2015, 02:48 PM	#6
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: Capacitance for Ford horns Sponsored Links (Register now to hide all advertisements) Most of the early cars that didn't have a horn relay had a capacitor. The capacitor also helps get the vibrator function going with its stored charge as well as limiting the arcing of the points. They will function without a cap but will function a lot better with one. Using a proper relay will get more power direct to a horn than the old design circuits will if properly taylored to the application.