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Re: [oletrucks] External Coil Resistor

To: oletrucks@autox.team.net
Subject: Re: [oletrucks] External Coil Resistor
From: Thomas Allen <thomasa@halcyon.com>
Date: Fri, 07 May 1999 22:28:18 -0700
Hi All:

Pardon me if I omitted an important point in my earlier post.  

Not all coils have the same primary-side reisitance. So check the
resistance of the ballast resistor and the coil. A balast resistor with
resistance equivalent to that of the coil will cut the voltage to the coil
in half. Ohms law. So a 6V coil having, say, 1.5 ohms primary resistance in
series with a ballast resistor of 1.5 ohms will get six volts at the coil
on a 12 V system. 

A 12 V coil having 3 ohms resistance will draw the same current as the six
volt coil, above, with balast resistor. 

 With Ohms law you can figure out how much current you should be putting
through the points by measuring the resistance  of the original components
that were intended for your application. So any combination of coil and
resistor that draws the same resistance should not tax the points.

Ohms Law -- I = E/R
Where: I = Amps; E = Volts; R= Ohms

Tom Allen
51 3800

At 06:37 PM 5/6/99 -0400, Bill Bailey wrote:
>>
>>The purpose of the resistor, is to allow the full 12 volts for cranking,
>>then it cuts the voltage down to conserve the points.  Now, as I said, I
>>could be wrong, but this is the way it was explained to me, and made sense
>>then and now.
>>
>
>Yep, that's the way I understood it to be too.
>Bill Bailey
>57 Chevy 3100
>http://members.tripod.com/~oltruck
>oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> 
Tom Allen
Seattle, WA

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