Homemade simple remote control switch circuit

The characteristic of this remote control switch is that it does not require a special remote control mobile phone. It can be operated remotely with a ready-made color TV remote control at home. It can very conveniently control the on and off of household appliances. The remote control distance can reach six or seven meters. The circuit principle is shown in the figure. In the picture, IC1 is the color TV remote control receiver. The ① pin is the ground, the ② pin is the +5V power supply terminal, and the ③ pin is the signal output terminal. When no signal is received, it is about +3.6V, when the signal is received, it is about 0V. IC2 is CD4017 Decimal counting/decoding integrated circuit. The DC 12V voltage obtained after step-down, rectification and filtering of the AC 220V power supply is used as the working voltage of the relay. +12V is then limited by R2 and VD is stabilized to obtain +5V to power other parts of the circuit. In static state, T1 is turned on, the state of IC2 is Q0=1 and remains unchanged, and the indicator LED lights up. When any button on the remote control is pressed, the ③ pin of IC1 outputs a series of low-level pulses. After smoothing by C4, T1 changes from conduction to cut-off, and the pin of IC2 inputs a positive pulse, Q0=0, Q1=1 , T2 conducts, J pulls in, and the controlled household appliances are powered on. When the remote control is pressed again, Q1=0, Q2=1. Since the Q2 terminal is connected to the IC2 pin, IC2 is reset and Q0=1. Therefore, J loses power and the controlled appliances are powered off.