Electronic time registering device

Claim 1

AN ELECTRONIC ELAPSED TIME METER FOR REGISTERING THE HOURS OF OPERATION OF A DEVICE, INCLUDING IN COMBINATION, A RELAXATION OSCILLATOR HAVING A UNIJUNCTION TRANSISTOR, MEANS INCLUDING A ZENER DIODE COUPLED TO SAID TRANSISTOR TO APPLY A REGULATED VOLTAGE THERETO, SAID OSCILLATOR INCLUDING TIME BASE MEANS FOR PERIODICALLY TURNING ON SAID UNIJUNCTION TRANSISTOR INCLUDING A CAPACITOR, A VARIABLE RESISTOR AND A THERMISTOR, SAID THERMISTOR ACTING TO COMPENSATE FOR THERMAL VARIATION OF SAID CAPACITOR, A TRANSISTOR CONTROL AMPLIFIER HAVING FIRST AND SECOND STAGES AND INPUT AND OUTPUT CIRCUITS, MEANS COUPLING SAID OSCILLATOR TO SAID INPUT CIRCUIT OF SAID AMPLIFIER, SAID CONTROL AMPLIFIER INCLUDING CAPACITOR MEANS COUPLING SAID SECOND STAGE OF SAID AMPLIFIER TO SAID FIRST STAGE THEREOF TO PROVIDE POSITIVE FEEDBACK, SAID CONTROL AMPLIFIER BEING RENDERED CONDUCTING BY PERIODIC PULSES APPLIED THERETO BY SAID UNIJUNCTION TRANSISTOR, AND COUNTER MEANS INCLUDING AN ACTUATING ELECTRIC SOLENOID COUPLED TO SAID OUTPUT CIRCUIT OF SAID AMPLIFIER, SAID COUNTER MEANS INCLUDING COUNTER WHEELS ACTUATED BY EXCITATION OF SAID SOLENOID DURING SAID PERIODIC CONDUCTION OF SAID CONTROL AMPLIFIER TO REGISTER THE NUMBER OF PERIODS OF CONDUCTION OF SAID RELAXATION OSCILLATOR.