Rice cooker timer circuit

The working principle of the circuit: The M and N terminals are connected to the two terminals of the rice cooker power lever switch.
When the rice cooker is powered on and working, the M and N terminals are short-circuited and the timer does not work. Ic, Ic2
is a dual monostable trigger with two independent monostable circuits. Each
monostable circuit has two trigger input terminals A1, A2 and B. , B2,
the trigger pulse input from terminals A1 and A2 acts on the rising edge, and terminals B1 and B2 should be connected to high level ;
the trigger pulse input from terminals B1 and B2 acts on the falling edge, A. , A2 terminal should be connected to low level. The monostable time of lC1 and
IC
2 is determined by R4, C3 and R5, C4. According to the values ​​in the figure, they are IO min and 10 s respectively. CD is the reset terminal and can be connected to high level .