|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
12-05-2020, 02:40 PM | #1 |
Senior Member
Join Date: May 2010
Location: Woodstock, Illinois
Posts: 597
|
12 volt system on a Model A
Hi All, I am not familiar with the 12 volt conversions for the Model A so I have a question. I thought the output of the ceramic mounted resistor would be 6volts going to the ignition switch and then on to the distributor points. The one I have in the shop is 12volt in and also 12 volts out??? I do not understand thanks for the help, Ken
|
12-05-2020, 03:53 PM | #2 |
Senior Member
Join Date: May 2010
Location: Austin, Texas
Posts: 925
|
Re: 12 volt system on a Model A
I think this is what you are seeing:
With the ignition switch closed and the points OPEN you will see "static" voltage (12 volts)at the output of the ceramic resistor. With the ignition switch closed and the points CLOSED you will see 6 volts at the output of the ceramic resistor. A function of current flow.
__________________
I noticed the harder I work the luckier I get! |
Sponsored Links (Register now to hide all advertisements) |
|
12-05-2020, 04:43 PM | #3 |
Senior Member
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 7,496
|
Re: 12 volt system on a Model A
What MAG says.
__________________
I'm part of the only ever generation with an analogue childhood and a digital adulthood. |
12-05-2020, 08:55 PM | #4 |
Senior Member
Join Date: Sep 2017
Location: Mint Hill, North Carolina
Posts: 386
|
Re: 12 volt system on a Model A
Yup. There is a formula for that.
E (Voltage) = I (Current) x R (Resistance) What happens is 6 volts are 'dropped' across the resistor when the points are closed, so that the coil sees 6 volts rather than 12 volts. E (6 volts) = I (4 amp Current Thru Coil) x R (1.5 ohms of ballast resistor) |
12-05-2020, 10:39 PM | #5 |
BANNED
Join Date: Dec 2019
Posts: 1,196
|
Re: 12 volt system on a Model A
Or just convert to a full 12v system,no resistors needed
|
12-05-2020, 10:52 PM | #6 |
Senior Member
Join Date: May 2010
Location: Alabama
Posts: 8,099
|
Re: 12 volt system on a Model A
Sponsored Links (Register now to hide all advertisements)
|
12-05-2020, 11:06 PM | #7 |
Senior Member
Join Date: May 2010
Location: Alabama
Posts: 8,099
|
Re: 12 volt system on a Model A
With a three OHM coil the ignition will also operate on 12 volt . If a resistor and six volt coil are used , the ignition will be running on a weaker six volts and won't run as well .
|
12-06-2020, 10:35 AM | #8 |
Senior Member
Join Date: Dec 2017
Location: Guthrie, OK
Posts: 1,144
|
Re: 12 volt system on a Model A
Except they are two different coils. The "weaker" voltage drives the "stronger" coil, which the car has had all along. The two arrangements should be equivalent. The resistor just wastes >30W of power in heat.
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|