What ballast resistor do you use for the aftermarket electronic ignition system?

great explanation here


FYI.....on the ORIGIONAL issue of the MOPAR ECU's system (approximately 1973 +/-) used the four pin ballast resistor. The resistor had two sections: one section was 0.5 ohms, used to control the coil primary current and the other section of the ballast resistor was 5.0 ohms, which applied a constant voltage to the internal components of the ECU. The wiring was "keyed" to insure correct connections. The external switching transistor switched the coil current on/off to create the spark controlled by internal components of the ECU. These internal components controlled the DWELL function (ON time of the switching transistor to charge the coil's primary winding and to determine when the spark event occured to begin the next recharge event) and to turn OFF the switching transistor to create the spark.
Later editions of MOPAR ECU redesigned the circuitry of the ECU to eliminate the need for the separate 5.0 ohm section of the ballast resistor, using just the 0.5 ohm resistor to control the coil primary current. .....ITS JUST THAT SIMPLE......
BOB RENTON