Flow meter

Claim 1

IN A FLUID FLOW METER, A HOUSING HAVING FLUID INLET AND OUTLET OPENINGS, A ROTOR ROTATABLY SUPPORTED IN SAID HOUSING TO BE DRIVEN BY FLUID FLOW THERETHROUGH, AN INDUCTOR COIL HAVING A PAIR OF OUTPUTTERMINALS, MEANS FOR INCLUDING VOLTAGE VARIATIONS IN SAID COIL IN RESPONSE TO ROTATION OF SAID ROTOR TO PRODUCE AT SAID OUTPUT TERMINALS AN UNDULATING ELECTRICAL SIGNAL WHOSE AMPLITUDE AND FREQUENCY ARE PROPORTIONAL TO THE ROTATIONAL VELOCITY OF SAID ROTOR, A TRANSISTOR AMPLIFIER CIRCUIT HAVING EMITTER AND BASE TERMINALS AND A COLLECTOR, MEANS ELECTRICALLY CONNECTING ONE OF SAID TRANSISTOR CIRCUIT EMITTER AND BASE TERMINALS TO ONE OF SAID INDUCTOR COIL OUTPUT TERMINALS, MEANS ELECTRICALLY CONNECTING THE OTHER OF SAID TRANSISTOR EMITTER AND BASE TERMINALS AND THE OTHER OF SAID INDUCTOR COIL OUTPUT TERMINALS TO A FIXED REFERENCE VOLTAGE SOURCE, A TRIGGER CIRCUIT, MEANS ELECTRICALLY CONNECTING THE INPUT OF SAID TRIGGER CIRCUIT TO THE OUTPUT OF SAID AMPLIFIER CIRCUIT TO RESPOND TO THE AMPLIFIER OUTPUT SIGNAL FOR PRODUCING A SIGNAL OF PREDETERMINED FORM, AN ELECTRICALLY ACTUATABLE REGISTER OPERATIVELY CONNECTED TO THE OUTPUT OF SAID TRIGGER CIRCUIT TO BE ACTUATED BY SIGNALS PRODUCED BY SAID TRIGGER CIRCUIT, AND GAIN CONTROL FEEDBACK MEANS CONNECTED BETWEEN SAID COLLECTOR AND SAID ONE TERMINAL OF SAID TRANSISTOR AMPLIFIER CIRCUIT FOR (A) UTILIZING THE FULL GAIN OF SAID AMPLIFIER CIRCUIT TO PRODUCE SAID AMPLIFIER OUTPUT SIGNAL UP TO A PREDETERMINED FREQUENCY AND (B) FOR DECREASING SAID GAIN AS SAID UNDULATING SIGNAL INCREASES ABOVE SAID PREDETERMINED FREQUENCY TO AVOID A POSSIBLE VOLTAGE BIAS SHIFT ON SAID TRIGGER CIRCUIT.