DELCO-REMY Transistorized: Operation

With ignition switch turned on, engine not running, current from battery flows through ballast resistor to control unit. Current then flows through transistors TR-1 and TR-2, resistors R-l, R-2 and R-5, and the coil primary winding and resistor R-8 to ground.

NOTE: Full current flows through coil primary winding, and condenser C-l is charged with positive voltage towards transistor TR-2.

When engine is running, vanes on rotating pole piece (iron core) in distributor line up with internal teeth on pole piece, establishing a magnetic path through center of pickup coil, and inducing a voltage in pickup coil. This voltage causes transistor TR-3 to conduct, resulting in current flow as follows: Charged condenser C-1 causes transistor TR-2 to turn off which causes transistor TR-1 to turn off, interrupting the circuit to ignition coil primary winding. The high voltage required to fire the spark plug is induced in coil secondary winding.