Transistor time relay circuit three

Transistor time relay circuit three

This circuit can achieve long delay times without using large capacitors . When the capacitor C1 =lOOvF,
the timing time can reach more than 1.5h.
    The timing portion of the circuit uses a "multiplier capacitor". That is, the charging current Jb of capacitor Cl is much smaller than the charging current IR in an ordinary RC circuit
, so under the same RC parameters, its charging time constant will be much larger than that of an ordinary RC circuit.
    Adjust the potentiometer RP to change the timing time. Capacitor C2 is an anti-interference capacitor .