Delay circuit using photocoupler

Delay circuit using photocoupler

It uses an optocoupler , which has the characteristics of strong anti-interference, fast response, long life and
high reliability.
    A direct-coupled amplifier is composed of transistors VTi and VT2, which improves reliability. A three-terminal fixed voltage regulator A is used as the
DC working power supply . After the power is turned on, the bidirectional thyristor V is turned on and the load Rfz power supply is turned on. After a delay, V
is turned off and the power supply is cut off.
    The maximum delay time of this circuit reaches th. Adjust the potentiometer RP to change the delay time.