Voltage compensation for noise in a frequency meter

Claim 1

A STABILIZED FREQUENCY DETECTING CIRCUIT COMPRISING MEANS FOR GENERATING NOISE SIGNALS CONNECTED AT THE INPUT OF SAID FREQUENCY DETECTING CIRCUIT, FREQUENCY DETECTING ELEMENTS, AN INDICATOR CONNECTED TO THE OUTPUT OF SAID DETECTING ELEMENTS, AMPLIFYING MEANS CONNECTED BY A TRANSFORMER TO THE INPUT OF SAID DETECTING ELEMENTS, SAID AMPLIFYING MEANS INCLUDING AN INPUT TRANSISTOR HAVING ITS BASE CONNECTED TO AN A.C. INPUT TERMINAL, ITS COLLECTOR CONNECTED TO THE PRIMARY WINDING OF SAID TRANSFORMER, AND ITS EMITTER CONNECTED TO THE OTHER END OF SAID PRIMARY WINDING, MEANS APPLYING A D.C. SOURCE TO SAID COLLECTOR TO PROVIDE ACTIVATION POTENTIAL TO THE TRANSISTOR, A ZENER DIODE CONNECTED BETWEEN THE D.C. SOURCE AND SAID OTHER END OF THE PRIMARY WINDING TO MINIMIZE THE POWER SUPPLY RIPPLE AND REGULATE THE VOLTAGE APPLIED TO THE TRANSISTOR, SAID GENERATING MEANS ELIMINATING ERRONEOUS UP-SCALE READINGS ON SAID OUTPUT INDICATOR.