Water tank automatic water supply control circuit

Working principle of the circuit: After the voltage of 380 V is reduced to a low voltage of 6.3 V by the transformer T, it
is converted from VD. ~VD. After full-wave rectification and C2 filtering, the working voltage is provided for the base time circuit NE555
; when the water level drops below the sun, pin 2 of NE555 is at low potential , and its internal trigger
circuit flips, and pin 3 outputs high level, and the relay K Get electric action, double knife contact
K. 1. The closed motor is started to pump water, and at the same time K. : closed, the wiring at point C is
short-circuited; when the water level rises to point A, the power supply voltage passes through R. , 4, and four points make the potential of pins 2 and 6 of
NE555 rise to high potential . Pin 6 is the high trigger end of the time base circuit. When
its voltage value reaches 2/3 VOD, the internal circuit flips over, causing the output of pin 3 to turn to
low level, and K loses power and releases Ki_,, K. 1: The motor stops working, the BC connection contact
jumps open, the AB connection is short-circuited, and the circuit enters the waiting state. When the water level is lower than point A
but higher than the mouth point, press button K2 to manually fill the water tank.