Control circuit for switching on electronic appts. - has capacitor powered transistor operated by base input signal and holding over switched on circuit

摘要

The control circuit is for switching on power to electronic or electrical appts. by sending a control signal into the controlling transistorised amplifier. The ac supply (14) is used to charge a capacitor (7) so that a ready source of power exists for the transistor (5) to operate with its collector load relay (3) when the control signal is received at its base (6). The transistor (5) and relay (3) get their holding current from the centre tap (13) of the equipment input transformer (1) via a diode (12), resistor (11), zener (8) circuit. The relay (3) is used to connect (2) the power supply (4) directly to the input transformer (1) of the equipment. The charging current for the capacitor (7) is via a high resistance (10) and therefore insufficient as holding current, hence the separate holding supply from the then switched-on transformer primary.