AC to DC converter with voltage regulation

Claim 1

An arrangement for converting AC input power to DC output power at a reference voltage, comprising: a capacitor; rectifying means for rectifying said AC input power; controllable switching means coupled between the output of said rectifying means and said capacitor for supplying current to charge said capacitor including a first transistor arranged with its collector and emitter in a current carrying path between said rectifying means and said capacitor and a second transistor coupled to the base of said first transistor; first means responsive to the rectifying means output voltage being above a predetermined threshold for preventing said switching means from supplying said current, including a first voltage divider connected across the output of said rectifying means and having first and second resistors connected in series, and first coupling means for coupling the junction of said first and second resistors in said first voltage divider to the base of said second transistor; and second means responsive to the voltage across said capacitor being greater than said reference voltage for preventing said switching means from supplying said current, including a second voltage divider connected across said capacitor and having third and fourth resistors connected in series, and second coupling means for coupling the junction of said third and fourth resistors in said second voltage divider to the base of said second transistor, and wherein said first and second coupling means together form an OR circuit consisting of a respective diode having its anode connected to the respective resistor junction and its cathode connected to said second transistor base.