Abstract: Voltage regulating circuitry maintains a load voltage of a DC to DC converter within a prescribed range. For that purpose, an SCR latching switch is connected to conduct upon the load voltage increasing to a predetermined upper level, and to become non-conductive in response to the load voltage decaying from the upper level to a predetermined lower level. Bistable switching circuitry, connected to an output of the SCR switch, serves as a current source in response to the SCR conducting, and as a current sink in response to the SCR latch becoming non-conductive. The bistable circuitry provides "snap action" control of an output transistor, which is coupled to the converter, when its load voltage rises and falls, respectively, to the upper and lower levels of the prescribed range, so that the voltage regulating circuitry has a stable, well defined hysteresis.

Abstract: A capacitive load driver circuit which has good response time without cross-conduction includes a positive drive subcircuit for charging an output load in response to a first input logic signal, and a negative drive subcircuit for discharging the output load in response to a second logic signal. The charging rate of the positive drive subcircuit is greatly increased only during the existence of a predetermined difference between the actual and desired output voltage. The discharge rate of the negative drive subcircuit is greatly increased only when the rate of discharge exceeds a predetermined value.

Abstract: In a demodulator circuit for processing a frequency-modulated (fm) signal, two rectangular-wave signals of opposite phase are generated from the fm signal and separately processed in two similar circuit paths. Each circuit path includes an inverter that receives one of the rectangular-wave signals and a NOR gate that receives both the rectangular-wave signal and its inverted version from the inverter. By imparting a slight delay on positive-going transitions of the inverted signal, a pulse stream is produced by the NOR gate in coincidence with such transitions. The pulse streams from both paths are combined to obtain a resultant signal having a pulse repetition rate that is twice the frequency of the fm carrier. Temperature-caused pulse variations in one circuit path relative to the other . . . which will allow the fundamental carrier frequecy to reappear . . . are stabilized by having the inverters, and the NOR gates, in thermally-coupled packages.

Abstract: A battery power indicator for a DC to DC flyback converter is responsive to the current flowing in the secondary winding of the converter's transformer. In one embodiment the power indicator is lighted when the battery is weak but not dead. If the battery is good, the indicator is bypassed and remains off. In a second embodiment, the indicator is lighted to indicate a good battery and when the power capability of the battery drops below a predetermined level, the indicator turns off.

Abstract: A DC to DC flyback converter for charging a capacitor in which the maximum current supplied from a battery to the converter's transformer is determined solely by the battery recovery voltage, circuit resistances, the transformer turns ratio and semiconductor junction voltages.