Sub-ultrasonic remote control circuit

The sub-ultrasonic remote control switch introduced in this example is controlled by a compressed air sub-ultrasonic whistle (made of rubber, with olive shape and oblate shape). When in use,
pinch the sub-ultrasonic flute with your hand, and the remote control switch will be turned on; pinch the sub-ultrasonic flute again, and the switch will be turned off. This sub-ultrasonic remote control switch can be used to control
lighting, exhaust fans and some small electrical equipment.
    (1) Circuit composition The sub-ultrasonic remote control switch circuit
consists of a power circuit, a sub-ultrasonic control circuit, a bistable trigger and a control execution circuit.
    The power circuit consists of a fuse FU, a step-down capacitor Cl, a resistor Ri and a rectifier diode VD1 , VD2, filter capacitor C2 and voltage stabilizing
diode vs.
    The sub-ultrasonic control circuit is composed of sub-ultrasonic sensor B, transistors VT1, VT2, diode VD3, resistors R2, R3, inductor L and capacitors
G and C5.
    The bistable flip-flop is composed of transistors VT3 and VT4, diodes VD4 and VD5, resistors R4 and R, and capacitors C5 and CH.
    The control execution circuit is composed of transistor VT5, resistors Rio, Ru, light-emitting diode LED and relay K.
    After the AC 220 volt voltage is stepped down by CJ, rectified by VD1 and VD2, filtered by G and stabilized by vS, a 9V DC voltage is generated, which is supplied to the sub-
ultrasonic control circuit, bistable trigger and control execution circuit.
    (2) Circuit principle When the sub-ultrasonic flute is pinched by hand, the sub-ultrasonic sensor B converts the received sub-ultrasonic signal into an electrical signal.
After the signal is amplified by VT1 and VTZ, it triggers the bistable trigger to make it Transform from one state to another.
    If the bistable trigger outputs a low level when the subsonic flute is not pressed, VT5 is cut off and K is in a released state. The LED does not light up, the output
capture base xs Yuan Dian J gross output, and the load (electrical equipment) does not work.
    When the ultrasonic flute is pinched, the bistable flip-flop changes to another state, outputs a high level, and turns on VT5. K pulls in, its normally open
contact is connected, and the working power is provided to the load through xs. At the same time, the LED lights up, indicating that the sub-ultrasonic remote control switch is in the on state. Pinch the
sub- ultrasonic flute again, VT5 will be cut off, K will be released, the voltage on xs will disappear, and the LED will go out, indicating that the remote control switch is in a closed state.