Automatic flush control circuit

Circuit working principle: The controller uses infrared photoelectric control to realize automatic
flushing. It consists of two parts: transmitting and receiving. Figure a is the electrical schematic
diagram of the transmitter part. 220 V is stepped down by the capacitor, rectified and filtered, and then supplied to the circuit. lC.
A multivibrator with a duty cycle of 90% and a frequency of 700 Hz is constructed . Pin 3 of IC controls
the infrared light emitting tube to emit light pulses . Figure b is the electrical schematic
diagram of the receiving control part. The photosensitive receiving part is a silicon photocell. The infrared light pulse is converted into an electrical signal ,
amplified by two levels of VT, VT2 (9014 type), and
then input to pin 2 of IC
2 after being detected by VD, VD2 (2AP9 type). IC: It is still a 555 circuit, forming a monostable circuit here . When there is an infrared light pulse, the voltage of pin 2 of IC2 is higher than 3V,
so pin 3 of the output terminal of IC2 is low level, and the thyristor is cut off because there is no trigger signal . When
the infrared light pulse is interrupted, the voltage of pin 2 of IC 2 is zero, and pin 3 of IC 2 becomes high voltage.
One way triggers the bidirectional thyristor vs (M94A4 type) to conduct, and the solenoid valve is energized to open
the flush ; the other way is connected to the light source. Diode indicates operating status. The receiving control circuit still uses the
capacitor step-down method for power supply, but a Zener diode is added.