Electronic spark timing adjustment circuit

Abstract

An electronically adjustable spark timing signal is provided for an internal combustion engine to be used in conjunction with a breakerless constant percent dwell output electronic ignition system. A monostable multivibrator circuit uses two constant current sources, one of which is adjustable, to produce an electrical signal the pulse width of which, under static conditions, is representative of the predetermined amount of desired advance or retardation required for efficient engine operation at all speeds, the pulse width of the output signal also varies as a function of engine speed and provides automatic dynamic advance with increasing speeds. This electronic timing adjustment signal is then combined, in a delay circuit, with the digital output of a constant percent dwell circuit to provide an adjusted spark timing signal which controls the operation of the ignition coil.