IMPROVEMENTS IN OR RELATING TO VOLTAGE STABILISED POWER SUPPLY UNITS

摘要

1282159 Controlling converters MARCONI CO Ltd 3 Nov 1969 [23 Jan 1969] 53723/69 Heading H2F [Also in Division G3] A power supply providing a number of stabilized D.C. voltages of different values comprises a transformer T2 having a plurality of secondary windings each feeding a respective rectifier R1, R2, R3 and output filter Fl, F2, F3 and having a primary winding fed through phaseopposed transistors Tr1, Tr2 controlled by driving pulses produced by an external drive circuit, which is controlled by an error voltage obtained from a comparison of an output voltage of the transformer T2 with a reference voltage, the arrangement being such that the mark/space ratio of the driving pulses is varied to maintain the D.C. voltages constant. A winding AP of transformer T2 supplies a rectifier PR1 to produce a mean value of voltage which is compared with a reference voltage produced by a Zener diode Z1 The resulting error signal from a transistor Tr7 controls the duration of drive pulses produced by an astable generator MAS, the arrangement being such that part of the full square wave produced by this generator is cancelled by a variable duration pulse produced by a monostable circuit MMS forming part of a coincidence circuit. The resulting pulses are alternately reversed by a modulator comprising transistors Tr8, Tr9 and are then amplified by transistors Tr10, Tr11 for application to an impedance matching transformer T3 supplying the bases of transistors Tr1, Tr2. Transformer T2 and transistors Tr1, Tr2 may be supplied with an input D.C. voltage from a transformer/rectifier T1, PR or from a battery B. The external drive circuit is provided with a stabilized supply via terminals a-a and members Tr12, Z2.