The ignition coil.

The coil P/N is IC4021Nis a closed E core design with a primary resistance of 0.5 ohms and inductance of 7.5 mh. With a 14v supply it takes about 2 milli seconds to reach 5 amps.

The trigger is designed to to provide 2 milli seconds of dwell time at about 3600 rpm. This produces a nice healthy spark with minimum wasted power.

The ballast resistors.

The ballast resistors are a pair of 13.8v 50w lamps , I am using these instead of resistors because of there varying resistance property.

They are about 0.3 ohms when cold and about 4 ohms when hot. When starting because the start disk slot is so small the coil is only on for

a few milli seconds so the element does not have enough time to heat up , the resistance stays low and therefore the current can build to 10 + amps

and create a very high energy spark. Ideal for starting. If the engine stops with the slot over the sensor the lamp comes on and reduces the

current to 3 or 4 amps.