Abstract: A 12 volt input is supplied to a timer providing a square wave output with an approximately 50% duty cycle. The output is applied to the bases of a pair of transistors and the collectors of the transistors conduct when a drive motor is in either the forward direction or the reverse direction. During the time that a particular transistor is conducting, its collector current rises to a point of cutoff. At this time, energy stored in a transformer circuit is released to the secondary of the transformer circuit. To regulate the increase in voltage in the secondary, diode clamping is accomplished by a common string of zener diodes connected to the output of the secondaries of th transformer circuits and to the emitters of the transistors. By adding additional zener diodes in the secondary circuits of either of the transformer circuits, a change in the high voltage output for that particular transformer is accomplished.

Abstract: Apparatus is described for converting alternating current at line frequency (50 or 60 Hz) into alternating current of much higher frequency and at a voltage suitable for operating loads such as lamps which draw high starting currents. The apparatus has a current feedback inverter oscillator which may be implemented by switching transistors connected in push-pull relationship through output and feedback transformers which have windings connected in series with the load. The load current is fed back through the feedback transformers so as to self-excite the oscillator at a frequency much greater than the line frequency. A sensing circuit responsive to the current which is fed back provides a control voltage. A clamping circuit is responsive to this control voltage and clamps the voltage at the base of the switching transistors so as to reduce collector peak current within the ratings of the transistors during high peak current draw conditions as occurs during lamp load turn-on.

Abstract: A wide range power conversion system which produces a highly regulated output over a wide range of variations in input AC source frequency and magnitude. A square full duty cycle voltage waveform is provided to current limiting means comprising a saturable-core reactor. The waveform has substantially constant volt-second characteristics, and the current produced by the waveform is controlled by the current limiter to provide a constant magnitude current to a load.