High reliability universal timer (CC4518, CC4001) circuit

(1) Introduction to circuit principle Figure 3-18 shows a high-reliability universal timing circuit. The timing time of this circuit can be deleted from 0.1~:99.9. The timing
method is BCD counting type. The control state can enable the socket cz to supply power or cut off power regularly. fIC2 and IC3 are each cascaded BCD counter/distributor
, Kl. K3 is the BCD decoding command timing selection switch, IC1 is the RS flip-flop and timing time base oscillator, and AN is the timing control
state selection. When the DC power supply is connected, the circuit is automatically cleared, the timing time starts, and the relay J is connected to AN to work in the preset state. If the scheduled time
is up. Al. A3 outputs high level, RS triggers and changes state, J also changes state, the oscillator stops oscillating, the LED goes out, and the timing time
ends.
    (2) Component parameter selection Selection of components