Regulated d.c. power supply

Claim 2

A regulated DC power supply comprising: a full-wave rectifier having input terminals adapted for connection to a source of AC line voltage; an output voltage filter coupled to said rectifier and having output terminals for connection to an external load; control means including a multivibrator having no more than one stable state for generating a square-wave control voltage having a predetermined nominal duty cycle; means including a transistor coupled to said input terminals of said full-wave rectifier and to said control means for detecting zero crossings of said AC line voltage and to provide trigger pulses in response to said detected zero crossings for phase-synchronizing said square-wave control voltage with said line voltage; means coupled to said output terminals and to said control means for varying said duty cycle inversely with changes in the DC output voltage developed at said output terminals; voltage regulating means coupled to said rectifier and responsive to an applied control voltage for stabilizing said output voltage; and means coupled to said control means for applying the variable-duty-cycle control voltage to said regulating means.

Claim 3

A switching-type regulated power supply which dissipates little power, minimizes radio frequency interference and provides a constant DC voltAge output comprising: a first full-wave rectifier comprising a pair of diodes having a common return circuit and having input terminals adapted for connection to a source of AC line voltage; an output voltage filter coupled to said first rectifier and having output terminals for connection to an external load; a multivibrator having no more than one stable state for generating a square-wave control voltage having a predetermined nominal duty cycle; means including a second full-wave rectifier and a transistor coupled to said input terminals of said first full-wave rectifier and to said multivibrator for detecting the zero-voltage crossings of the AC voltage across said first full-wave rectifier and to provide trigger pulses in response to said zero-voltage crossings for synchronizing the beginning of its duty cycle period with said zero-voltage crossings; means coupled to said output terminals and to said multivibrator for varying said duty cycle inversely with changes in the DC output voltage developed at said output terminals; voltage regulating means comprising a switch coupled in series with said common return circuit and said output terminals and responsive to an applied control voltage for stabilizing said output voltage; and means coupled to said multivibrator for applying the variable-duty-cycle control voltage to said switch to switch it on in synchronism with said zero-voltage crossings thereby to eliminate radio-frequency-interference-causing current surges.

Claim 4

A switching-type regulated power supply which dissipates little power, minimizes radio frequency interference and provides a constant DC voltAge output comprising: a first full-wave rectifier comprising a pair of diodes having a common return circuit and having input terminals adapted for connection to a source of AC line voltage; an output voltage filter coupled to said first rectifier and having output terminals for connection to an external load; a multivibrator having no more than one stable state for generating a square-wave control voltage having a predetermined nominal duty cycle; means including a second full-wave rectifier and a transistor coupled to said input terminals of said first full-wave rectifier and to said multivibrator for detecting the zero-voltage crossings of the AC voltage across said first full-wave rectifier and to provide trigger pulses in response to said zero-voltage crossings for synchronizing the beginning of its duty cycle period with said zero-voltage crossings; means coupled to said output terminals and to said multivibrator for varying said duty cycle inversely with changes in the DC output voltage developed at said output terminals; voltage regulating means comprising a switch coupled in series with said common return circuit and said output terminals and responsive to an applied control voltage for stabilizing said output voltage; and means coupled to said multivibrator for applying the variable-duty-cycle control voltage to said switch to switch it on in synchronism with said zero-voltage crossings thereby to eliminate radio-frequency-interference-causing current surges.

Claim 5

A switching-type regulated power supply in accordance with claim 2, wherein said varying means comprises a zener diode in series with a variable impedance coupled from said output terminals to said control means.

Claim 6

A switching-type regulated power supply in accordance with claim 2, in which said multivibrator is powered by an auxiliary power supply coupled to said input terminals of said first full-wave rectifier, and in which said auxiliary power supply is unregulated for providing additional output voltage stabilization.

Claim 7

A switching-type regulated power supply in accordance with claim 2, wherein said switch included in said voltage regulating means comprises a transistor.

Claim 8

A switching-type regulated power supply in accordance with claim 2, wherein said switch included in said voltage regulating means comprises two transistors connected in a Darlington pair configuration.

Claim 9

A switching-type regulated power supply in accordance with claim 2, wherein said variable-duty-cycle control voltage applying means comprises an emitter follower.