Ignition system dwell control

Abstract From the Canadian patent

Abstract of the Disclosure, A control circuit for developing a digital signal for use in a closed loop dwell control of an electronic internal combustion engine ignition system. The circuit has a ramp counter and a down-counter. The ramp counter counts-up clock pulses for a period of time beginning when the primary winding of an ignition coil is energized and ending when primary winding current increases to a sensed current limit value. When current limit is reached, the most significant bits of the count in the ramp counter are loaded into the down-counter. The ramp counter is now counted-up and the down-counter is counted-down until the down-counter underflows. The final or ultimate count …