Re: Re: Re: Re: Re: Re: Re: Electrical Question

Posted by ltf in nc on September 01, 1999 at 19:15:52 from (206.228.213.149):

In Reply to: Re: Re: Re: Re: Re: Re: Electrical Question posted by The High School Electronics Teacher on September 01, 1999 at 18:29:06:

You need to do some research on the Kettering ignition system. I agree with your statement that the voltage reading will be as you indicated as long as the coil primary and the ballast are in series. However, there is more to this than the simple electrical circuit. The coil was designed to operate on approximately 6 to 9 volts and during the crank cycle to get 12 volts. The ballast resistor also serves to dampen oscillations between the coil primary and the capacitor across the points. This has to do with the "back EMF" and the 200 volts that is produced across the primary. Within the ignition system this can only be accomplished by having the ballast resistor electrically in the circuit from the switch to the primary side of the coil. I am sure you can better explain the EMF better than me. In your comment regarding 12 volt battery and a 6 volt coil we would be using a dropping resistor for voltage correction. Same type just a different name. Early 6 volt systems also used a resistor to lower the voltage to the coil to achieve the benefits mentioned above. In summary, all Kettering ignition systems need a ballast resistor. The ballast resistor belongs in the circuit from the switch to the primary side of the coil. Good day.

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