Bathroom automatic flush circuit

The automatic toilet flusher is modified on the basis of the ordinary toilet flusher. It flushes automatically once after use, which is simple and reliable. The power supply is completely disconnected when not in use
, which has the advantages of energy saving, easy use and long life.
    (1) Circuit composition The toilet automatic flush circuit consists of a power supply circuit, a monostable trigger and a solenoid valve control circuit, as
shown in Figure 1-47. The power circuit consists of the step-down capacitor C1, the rectifier diode VD1, the voltage stabilizing diode vs and the capacitor C2.
    (2) Working process When the toilet lid is opened, the switch S is turned on, and the AC 220V voltage is stepped down by cI, rectified by VD1, stabilized by vs and
filtered by G to provide working power for the circuit. ． . . ':
    The monostable trigger circuit is composed of a time base integrated circuit lc and related peripheral components. The initial voltage of the trigger terminal of pin ② of 1C is divided by Rz and R3
and then is higher than Vcc/3. Pin ③ of 1C outputs low level , the monostable trigger is in a steady state, the relay K does not operate, and the large-capacity capacitor 0 is charged.
Fully charged.
    After use, when the toilet lid is closed, the switch S is turned off and the circuit is powered off. Due to the isolation effect of VD2, the charge on cz is quickly
discharged by Rz and Po. The ② pin of lC becomes low level and is triggered. At this time, the large-capacity capacitor G supplies power to the IC through the diode VD3. The monostable circuit is
triggered and enters the transient state. The ③ pin of the IC becomes high level and the relay K is closed. K closes and locks itself to restore power to the circuit. K closes and turns on the solenoid
valve Y to start flushing. At the same time, the power supply charges C3 through the resistor. When C3 is charged, the potential of pin ⑥ of IC rises to 2Vcc/3.
The transient ends, pin ③ of IC turns back to low level, relay K is released, and K is disconnected, causing The entire circuit is powered off and flushing ends.
    The thyristor VTH is used in the circuit to discharge G to ensure that it is flushed only once. When the ③ pin of the IC just flips from low level to high level,
VTH is triggered to conduct, discharge G, and the voltage drops to 2~3V. If the G discharge circuit is not set, after the transient state of IC is over, the relay K is released
. K is suddenly disconnected, causing the circuit to lose power. The ② pin of the IC jumps to low level , and G provides working power to IC through VD3. The single The steady-state circuit
is triggered again, and relay K is closed again, and so on.