Abstract: A voltage-to-frequency converter is provided for generating a frequency which is proportional to the square of the input voltage provided to the converter. Since the input voltage is correlative to current flowing in a conductor, the output frequency exhibits a proportionality similar to the relationship between the temperature of the conductor and the current flowing in it. The arrangement includes two charging circuits which receive the input voltage and are alternately charged as a function of the input voltage. While the first charging circuit charges to a predetermined voltage, the second charging circuit discharges. Upon exceeding the predetermined voltage, the output of a flip flop is set to discharge the first charging circuit, and to charge the second charging circuit. When the second charging circuit charges to a predetermined voltage, the output of the flip flop is reset, so that the first charging circuit charges again.

Abstract: An improved power supply is provided for circuit breaker applications and draws power from the power lines which the associated circuit breaker protects. The alternating current on the power lines is sensed by a current transformer and rectified by a full-wave rectifier. The full-wave rectified signal is alternately switched between a low impedance path, which does not provide power to the power supply, and a charging path, which does provide power to the power supply. During the major portion of the a.c. cycle, the full-wave rectified signal follows the low impedance path without loading the current transformer or distoring the current signal. However, near the zero crossings of the a.c. current signal, the low impedance path is opened so that the full-wave rectified signal charges a charging circuit. The charging circuit feeds a voltage regulator to provide output power from the power supply.