A power supply for producing DC voltage with a minimum voltage drop from a source voltage that is either AC or DC in which the emitter-base junction of a transistor is coupled to the source so as to provide base current required to turn the transistor on, an output capacitor is connected in series with the emitter-collector path, and a capacitor and resistor are connected in parallel in the base circuit of the transistor.

Two full-wave bridge rectifier circuits embodying the invention are disclosed. In each rectifier circuit four transistors and four sets of transformer windings for controlling base current are connected in a bridge configuration. Each transistor is connected in an inverted mode so that voltage blocking is performed by its collector-base junction. High efficiency is achieved by controlling the base current of each transistor in response to the emitter current thereof so that the base current is proportional to the emitter current so as to minimize circuit losses.

Full-wave and half-wave rectifier circuits are disclosed; the former circuit using two transistors and the latter circuit using one transistor. In both circuits transistors are connected in an inverted mode so that, for example, with an NPN transistor current flow is such that line current flows into the emitter and load current flows out of the collector. Furthermore, voltage blocking is performed by the collector-base junction instead of the emitter-base junction. High efficiency is achieved by controlling the transistor base current in response to the emitter current so that the base current is proportional to the emitter current and is also at an optimum magnitude so as to minimize circuit losses.

Active full-wave rectifier circuit for a current transformer used for example in an earth leak detector circuit and comprising active components such as operational amplifiers and transistors to detect and process relatively weak output voltages.

A synchronous rectifier circuit employs therein a pair of synchronously-operated switches, each switch being coupled between a separate respective input terminal and an output terminal of the circuit. One of the synchronously-operated switches is gated ON when a voltage applied across the synchronous rectifier circuit input terminals is of one polarity, and is gated OFF when current therein becomes substantially zero. The second switch is gated ON when a voltage applied across the input terminals is of the opposite polarity, and is gated OFF when current therein becomes substantially zero.