TIMING CONTROL CIRCUIT FOR AN AUTOMOTIVE ENGINE IGNITION ANALYZER

摘要

An improved timing control circuit for an automotive engine ignition analyzer is disclosed providing an improved sweep signal for the oscilloscope of the analyzer and providing both retard and advance lamp triggering signals for driving a strobe lamp associated with the analyzer. The ramp generator incorporated provides self compensation for changes in the engine speed of revolution by employing a phase lock loop with phase detector, integrator and voltage controlled oscillator. The oscillator provides a ramp voltage for use as a sweep signal and input to the strobe lamp signal generator. The ramp voltage provides a sweep signal of substantially constant length while the engine speed varies over the range of idling to full speed. The timing control portion for the strobe lamp used in adjusting the timing of an internal combustion engine provides a signal which retards lamp triggering for setting ignition advance and a signal which advances lamp triggering for setting ignition retard, The circuit provides for advance and retard selection, the amount of advance or retard, and zero degree triggering for engines with various numbers of cylinders. The lamp circuit employs the ramp voltage synchronized with engine timing, a reference voltage for setting the amount of advance or retard, and a comparator which provides a triggering signal for the lamp when the ramp and reference voltages match.