Abstract: The present invention relates to a compact electrical power supply which derives electrical energy from a low frequency medium voltage source (e.g. a 120 V 60 Hz ac main), and converts the electrical energy to a low voltage format suitable for solid state signal processing equipment. The supply entails in succession bridge rectification means, a dc-dc boost converter, a capacitor storage bank, and a half bridge converter, either resonantly or non-resonantly operated. The converters operate at frequencies substantially above audible frequencies in the interests of compactness. The design provides a high input power factor (inductive) with minimum EMT, and provides a lengthened voltage hold up after loss of power.

Abstract: A Royer circuit, which includes an inverter and a saturating output transformer, is powered from a current source rather than from a voltage source, thereby reducing transistor current overshoot when the output transformer saturates. A current source inductor and a PWM (pulse width modulated) power transistor are series connected in the current return line of the inverter. The PWM power transistor emitter is connected so that potential between it and the common DC input power terminal will be low. This permits the PWM power transistor to be direct-coupled from a low voltage PWM switched mode power supply control circuit. A start-up circuit for supplying start-up power to inverter control circuitry from the DC input source is provided. Feedback loop control for the PWM power transistor is also provided.

Abstract: A control circuit for electrically heatable windshields of automotive vehicles which controls the quantity of heat supplied by the vehicle alternator to the windshield heating element to be adequate for deicing the windshield yet limited to avoid windshield damage and to minimize decoupling time of the alternator from the vehicle battery. The control circuit, which employs an inexpensively installed temperature sensor element that senses ambient temperature, responds to the temperature difference between the ambient and a reference deicing temperature and to the supplied heating power for controlling the duration of the heating period.

Abstract: A control circuit employed within an automotive electrical system for controlling the voltage transition rate between battery float and discharge levels in the presence of a switchable coupling between the battery and standard alternator. The control circuit includes means for regulating the alternator output voltage to said battery float level when the battery is coupled to receive charge current from said alternator, and for transforming said alternator output voltage to said discharge level at a predetermined rate prior to the battery coupling being switched to supply current to the load circuit, and further means for transforming said alternator output voltage to said float level at said predetermined rate after said battery coupling being switched to again receive charge current, whereby said predetermined rate provides a gradual change in the energization of said load circuit in the presence of the recited switchable coupling.