A Phase-Regulated Transistor Power Supply

Transistors have been utilized effectively for class A regulation of power supplies. However, the power-handling capacity and high-temperature performance of these power supplies are basically restricted because of the power-temperature limitation of transistors. This paper describes a type of regulated transistor power supply in which the dissipation in the regulator transistors is extremely small. This enables low-power transistors to control large amounts of power and permits substantial improvement of power supply capabilities at high temperature over that of the Class A regulated supply. The principle of operation of this supply is similar to that used in thyratron regulation. The regulator transistors are operated as rectifying switches whose conduction period is varied in phase with respect to the ac input. Regulation is obtained by controlling the conduction phase of the transistors in response to load and input voltage variation. A transistor switch circuit for this power supply is described together with general design and operating considerations for its power supply application. The performance of a 12-volt, 0 to 1-ampere developmental phase regulated power supply is discussed.