Electronic pulse repetition rate indicator

Claim 1

AN ELECTRONIC TACHOMETER FOR INDICATING THE SPEED OF AN INTERNAL COMBUSTION ENGINE HAVING A ROTATING MEMBER COMPRISING, A SOURCE OF IGNITION PULSES, A BISTABLE MULTIVATOR HAVING FIRST AND SECOND SWITCHING ELEMENTS, MEANS FOR APPLYING SAID IGNITION PULSES TO BOTH SAID FIRST AND SAID SECOND SWITCHING ELEMENTS FOR PRODUCING A RECTANGULAR WAVE PATTERN, THE LEADING AND TRAILING EDGES OF SAID RECTANGULAR WAVES BEING PRODUCED IN TIME COINCIDENCE WITH SUCCESSIVELY OCCURRING IGNITION PULSES, A DIFFERENTIATING NETWORK FOR PRODUCING ALTERNATELY POSITIVE AND NEGATIVE PULSES IN TIME COINCIDENCE WITH THE LEADING AND END TRAILING EDGES RESPECTIVELY OF SAID RECTANGULAR WAVES, CLAMPING MEANS BRIDGING A PORTION OF SAID DIFFERENTIATING NETWORK FOR ELIMINATING ALL OF SAID PULSES OF ONE POLARITY, AN AMPLIFIER COUPLED TO SAID DIFFERENTIATING CIRCUIT FOR AMPLIFYING THE PULSES OF THE OTHER POLARITY, A SOURCE OF SUPPLY CONNECTED TO SAID AMPLIFIER, MEANS COUPLED TO SAID SOURCE OF SUPPLY FOR REGULATING THE VOLTAGE APPLIED TO SAID AMPLIFIER, AND CALIBRATED INDICATING MEANS COUPLED TO SAID AMPLIFIER FOR INDICATING THE ANGULAR VELOCITY OF SAID ROTATING MEMBER IN ACCORDANCE WITH THE FREQUENCY OF SAID IGNITION PULSES.