Circuit for recognizing a pulse waveform and an ignition system for an i. c. engine including such a circuit

摘要

A pulse waveform recognition circuit includes an input stage consisting of a tuned circuit tuned to approximately the frequency of a sinusoid to half-waves of which the pulses to be recognized approximate. A transistor is biased to conduct weakly and has its base coupled to the tuned circuit so as to be turned on by a pulse within the band width of the tuned circuit. The transistor drives a monostable multi-vibrator with a frequency dependent feedback circuit which causes the reversion time of the multi-vibrator to decrease as the frequency of triggering increases and which also increases the threshold voltage required to trigger the monostable circuit as this frequency increases. The circuit is used in an ignition system for an i.c. engine.