G-650 C-4042 SPARK TIMING CONTROL A spark timing control for an electronic internal combustion engine ignition system that provides a constant spark advance regardless of engine speed. A series of crankshaft pulses are developed which occur at each 60 degrees of rotation of the crankshaft. The system has a source of constant frequency clock pulses which are counted up by an up-counter during 60 degree periods. The count attained by the up-counter during a 60 degree period is loaded into a down-counter. The up-counter is now counted up at a constant rate from zero and the down-counter is counted down at a constant rate from the count magnitude that was loaded into the down-counter. When the count magnitudes of the two counters are equal, a digital comparator that is connected to the counters develops an output signal that can be used to cause the firing of a spark plug.
