Multi-output transistor frequency converter - has measuring circuit coupled to additional winding of power transformer for controlling transistor switching

摘要

The converter provides several stabilised output voltages (UIT Ux), with an auxiliary winding (V) of the power transformer supplying a voltage proportional to the voltage across the secondary windings (II-IV) to a measuring circuit (M) adjusting the switching of the switching transistor (TS). The measuring circuit (M) has a capacitor (C3) which is charged and discharged via equal ohmic resistances (R1,R2). The charging resistance (R1) is bridged by a diode (D3) during discharging. The measured voltage is obtained from the capacitor (C3) via a voltage divider resistance (R3) with a high ohmic value relative to the charging and discharging resistors (R1,R2). The measured voltage is then fed via a regulating amplifier (RV) to a A/D converter providing the control signal for the switching transistor (TS).