Video apparatus for generating a conductively isolated control signal

摘要

An input signal for controlling a television power supply has "power-on" and "power-off" signal states. When the input signal is in the "power-on" state, it couples a clock signal to a primary winding of a transformer causing an alternating current voltage that is conductively isolated from the input signal to be developed across a secondary winding of the transformer. When the input signal is in the "power-off" state, it decouples the clock signal from the primary winding so that no alternating current voltage is developed across the secondary winding. The signal across the secondary winding is demodulated in a demodulator that produces a control signal that is conductively isolated from the input signal. The control signal is coupled to a regulator of the power supply. A power-on state of the control signal occurs when the alternating current voltage is developed at the secondary winding terminal. A power-off state of the control signal occurs when the alternating current voltage is absent.