Silent timer reminder circuit

　　Working principle of the circuit : After the power switch is turned on, the circuit automatically resets its operation so that each IC is in its initial state. The reference signal generating circuit 8651B generates a signal of 1/60 Hz, which is input to the reverse counting end of the counter 74HC192. 74HC192 is a presettable 4-bit forward and reverse counter. By changing the IC input terminal, it can be used as a forward or reverse counter .