IC engine ignition circuit control - has two Schmitt triggers with outputs connected directly and via delay circuit respectively to OR=gate

摘要

The engine injection circuit controlled as a function of the rotation angle. The circuit is based on the detection of positive or negative threshold levels at the engine phase sensor. The sensor (13) which may be a Hall effect device or an inductive arrangement directly activates two Schmitt trigger circuits (14, 15) and an inverted Schmitt trigger (16). One normal trigger and the inverting trigger are fed to an OR gate (18) the first via a delay (17). The OR-gate output then controls the first Schmitt circuit by varying the operating threshold level. The output from this latter circuit is used as the ignition control signal (20). The delay may be a simple RC-circuit. The Schmitt trigger is an operational amplifier accepting the OR gate output at its inverting input via a grounded emitter transistor.