Switching circuit for TV receiver - has collector of transistor connected to DC supply through transformer primary and emitter to earth through diodes

摘要

The switching circuit has a transistor (T) operated periodically, whose collector is supplied with voltage via the primary of an isolating transformer (TR) and whose emitter is earthed via a diode resistor chain (D1, D2, R3). A capacitor (C1) shunts the diodes. The emitter is connected to the power supply by a resistor (R1) of several hundred kilo ohms. The emitter's earthing resistor serves as a current-measuring resistor. The circuit is used to make the transistor conduct intermittently The secondary windings of the transformer supply various other parts of the TV. ADVANTAGE - Blocking voltage is maintained sufficiently large during pauses in transistor operation.