Abstract: A photovoltaic power supply and battery charging system comprises a photovoltaic solar energy power supply panel connected through a blocking diode to a secondary storage battery which, in turn, is connected to a suitable load. A temperature sensitive reference voltage is supplied to one input of a voltage comparator, the other input to which is connected to the battery and thereby varies in accordance with the variations of charge on the battery. A short circuit shunt switch is connected directly across the photovoltaic panel; and this shunt switch is opened for varying periods of time by the output of a variable pulse width generator. The pulse width generator, in turn, is connected to and is controlled by the output of the voltage comparator to produce pulses of different widths. The charging current supplied to the battery then occurs in the form of high current pulses of varying widths depending upon the charge state of the battery.

Abstract: A temperature monitoring and display system is used in conjunction with two or more low temperature sensors which produce output currents representative of the temperature being sensed. The currents produced are converted to voltages and applied through differential amplifier circuits to produce output analog signals representative of the sensed temperatures. These signals also are applied to a differential comparator which produces an output signal having a sign and magnitude representative of the difference in the sensed temperatures. A switch is used to select any one of the outputs of the first and second differential amplifiers or the comparator and to apply this output signal to an analog-to-digital converter, the outputs of which then are used to drive a suitable digital display.