Timer circuit for blasting

　　NE7555 and peripheral components form a clock oscillation circuit. The oscillation frequency period of NE7555 is adjusted by potentiometer BP. Its minimum time is 1 min and the maximum setting time is 10h. Each time the switch SB is pressed, the circuit will work for one cycle , then K pulls in, the normally open contact K1 closes, replacing the SB switch to turn on the power supply, and after a timer of 10 hours, K automatically releases the power outage. The timer circuit for blasting is as follows.