Re: 12v conversion for super a

Posted by John T on February 16, 2007 at 18:20:21 from (66.244.90.5):

In Reply to: Re: 12v conversion for super a posted by SuperA-Tx on February 16, 2007 at 16:40:40:

Tx,

Q Now from what I understand the resistor is to keep from burning up the points.

A Thats true cuz it (if actually needed and used) limits/reduces the current in the coils primary (its in series with it) which is the current they have to switch.

Q Isnt the resistor still needed even with a 12V coil?

A MAYBE A full true 12 volt coil has around 3 ohms of primary resistance which limits the points current to around 4 amps (about all they should switch to avoid premature burn up) AND THEY DO NOT USE ANY BALLAST

HOWEVER Some coils are labeled "12 Volts for use with external ballast" and they are in reality 6 volt coils and require a ballast, otherwise the points current is doubled and they burn up fast. A full true 12 volt coil is labeled "12 volts" or "12 volts NO Ballast Required" AND THEY DO NOT USE AN EXTERNAL BALLAST

Q I know you can get a coil with an internal resistor and I would go with that if I had it to do again. Mine has a 12 volt coil but I have a external ballast resistor as well.

A What some refer to as "Iternally Ballasted"
are 12 volt coils and the added primary resistance is usualy just cuz theres more wire length or else it has higher resistance wire, versus them having an internal discrete actual resistor. They DO NOT use an external ballast and if ones added, sure the points will last a longggggg time, buttttttttt the spark is weaker.

The typical full true 12 volt coil has around 3 ohms primary resistance yielding 4 amps of coil and points current, while a 6 volt coil may be more like half that, but since the voltage is halved the points current still remians around 4 or so safe switching amps to avoid premature points burn up.

Hope this helps

John T

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