Digital meter measuring IC engine speed - counts multiple pulses derived from ignition voltage or shaft rotation and determines ignition timing

摘要

The digital meter, for measuring the speed of an internal combustion engine, has a multiplier (7) to multiply the quantity representing engine speed (e.g. ignition voltage or current, shaft rotation). The output of the multiplier is gated (8) through to a counter (9). The gate is controlled by pulses of given frequency. To determine sparking advance or retard the gate is triggered by a signal derived from the triggering pulse of the flash light (15) used to set the ignition. To determine the contact angle of the distributor contact (3) the gate is closed for the time for which the contact is closed.