Light remote control switch circuit

The remote control switch circuit of the electric light consists of two parts, the transmitting part and the receiving part, as shown in the figure. Figure (a) is the transmitting part, which is a transmitter. Transistors VT1 and VT2 are self-excited multivibrators, and their collector loads are not resistors, but inductors. When the power switch SB on the stage is turned on, the oscillation circuit works, the two tubes are turned on and off in turn, and the current passes through the coil intermittently. Through the mutual inductance of L1 and L2, a high-frequency oscillation signal is directly radiated from the transmitting antenna WD1 to the space. The working band of the transmission can be determined by selecting the size of capacitors C2, C3 and resistors R1, R2. The oscillation frequency can be changed by adjusting capacitor c1.

Figure (b) is the receiving part. After the receiving antenna WD2 receives the electromagnetic wave in space, it selects the high-frequency oscillation signal emitted through the resonant circuit. Since this signal is strong, it is added to the base of the transistor VT3, making VT3 saturated and turned on. After the triode detection and the composite tube composed of VT3 and VT4 amplification, a large current passes through the collector of the transistor and VT4, so the relay KA connected in series to the collector of VT4 is attracted. When the relay KA is activated, it drives the actuator to control the on and off of the light. When in use, press the button SB of the transmitter. The receiver fixed on the light switch works, the relay armature is attracted, and the ratchet is driven to rotate one tooth, and the light turns from bright to off or from off to bright.