A voltage regulator for an anode voltage supply in a CRT powered by a deflection flyback pulse generator includes a voltage sensing network for providing a feedback signal to a summing amplifier. A pulse sensing network which may be a capacitive divider is connected between the output of the flyback pulse generator and the input to the summing amplifier. The resultant output of the summing amplifier is the flyback pulse level shifted with respect to a DC level which is applied to a MOSFET switch to turn it on whenever the flyback pulse goes above the MOSFET's threshold. The output of the MOSFET switches current through a shunt capacitor coupled to the output of the deflection flyback pulse generator for altering its capacitance thereby regulating the height of the flyback pulses, and thus regulating the anode voltage supply.

A self-oscillating, high voltage DC power supply for a cathode ray tube drive. Included within the high voltage power supply are an oscillator coil connected to a DC supply and transistor switching means connected to the coil between the coil and ground so as to provide a charging circuit for the oscillator coil. Diode means and output filter are connected between the coil and the DC output to provide a smoothing of the ripple of the DC output. Included in the oscillator power supply are a feedback coil inductively coupled to the oscillator coil and wound in the opposite direction. The feedback coil is a part of a base drive circuit for the transistor switch. Included also are feedback resistance in series with the coil and these elements are connected between the base of the switching transistor and ground. The feedback coil operates to open the switch by means of current induced in the base drive circuit when the current in the feedback circuit reaches a predetermined level related to the current in the oscillator coil primary and thus the transistor. The feedback value is selected such that when the transistor switch reaches its saturation limit, it is shut down to prevent any further large currents therethrough which might damage the device and ultimately the cathode ray tube or any other components connected in the high voltage drive circuit. Preferred embodiments of the invention include high voltage regulation in conjunction with the self-oscillating DC drive.

A telephone power isolation system that will provide fused AC or DC power for multiple individually isolated telephone circuits using a single AC powered inlet and a multiple pair telephone connector for output connections. LED indicators are provided to illuminate and indicate a blown fuse condition that can be remotely observed and immediately identified.

A fly-back transformer to be used for use in the supply of a DC high voltage into a cathode-ray tube such as TV image receiving machine or the like. The ringing removing wire connected with the secondary winding through the distributed capacity with respect to the secondary winding to form a closed circuit of ringing current together with the secondary winding is connected in parallel to the primary winding through the DC resistance component, so that the ringing may be damped by the closed circuit.

A transformer coupled switching regulator power supply having current-limiting circuits and under-voltage detecting circuits on the primary side of the power transformer. The under-voltage detection circuit acts to substantially terminate the flow of current through the switching circuits in the case of a short circuit in the load.