Line frequency slaved voltage-to-frequency converter system

The system includes a synchronous voltage-to-frequency converter connected to receive an analog input signal voltage and to generate a train of output pulses. A counter is connected to receive and count the output pulses and a digital register is connected to the counter for periodically receiving and storing the count in the counter. A conversion interval timer circuit is connected to control the operation of the counter and the register to determine a conversion interval during which the output pulses from the synchronous voltage-to-frequency converter are accumulated in the counter and then stored in the register. The conversion interval timer circuit is operable to determine the end of a prior conversion interval and the beginning of a new conversion interval in response to a predetermined phase of a predetermined cycle of the ac power line voltage. A timer is provided for exact measurement of the duration of each conversion interval and a multiplier is provided for multiplying the number stored in the register by a function which is a reciprocal of the exact duration measurement from the timer to thereby contact the number for variations in the conversion interval.