Intermittent operation control circuit of electrical appliances

Circuit working principle: The IC model in the picture is CD4538B, which contains two identical
and mutually independent monostable triggers D. and D2, which are connected with peripheral components
to form a multivibrator. When the output terminal 14 pin is at high potential, the relay K is powered on
and the electrical appliance is energized to work; on the contrary, when the output terminal is at low potential, K is de-energized and
released, and the electrical appliance is powered off and stops working. The length of the high and low potential conversion time at the output end (
the length of power-on and power-off time of the electrical appliance) is adjusted through the potentiometers RP and RP2 respectively
. RP is used to adjust the power-on time, and RP is used to adjust the power-off time.
The length of power-on and power-off time (about 30 minutes respectively) can be adjusted independently without affecting each other
, so it is very convenient to use. When the power switch S is turned on, the electrical appliance M can automatically operate intermittently according to
the set power-on and power-off time periods.