Infrared remote control switch circuit diagram composed of CD4017

　　Most of the lighting lines in buildings nowadays are dark wires. If you use a 4-wire electronic switch to control these lights, you need to connect another power source and modify the line. This is time-consuming and labor-intensive, and affects the appearance. Today we are going to design and produce a single-wire infrared remote control switch. It has only a single input line and a single output line, and can directly replace the very popular wall switch in the home. It is very convenient to install and replace; it can also be easily remotely controlled.

　　1. Performance Introduction:

　　The advantages of this circuit are: ⑴ The circuit adopts the current transformer principle to boost the voltage, and uses diodes to limit and stabilize the voltage, which cleverly solves the problem of the switch's own power supply; ⑵ It has a wide range of applications and can be remotely controlled with a color TV or DVD player remote control. ⑶ It also has the advantages of small voltage drop and low power consumption.

　　2. Working Principle:

　　As shown in the figure, the AB end on the left side of the circuit is a single-line input and output end, which is connected in series with the load and then connected to the 220V mains. The integrated circuit CD4017 is connected into a bistable trigger circuit to control the unidirectional thyristor; SCR is used as a switch to control the on and off of the load, and the conduction of the thyristor is equivalent to the closure of the switch; the micro transformer B1 is used to solve the problem of the supply of its own power when the electronic switch is turned on; the diodes D1 and D2 are connected in parallel to the primary of the transformer to limit the primary voltage to about 0.7V, which can prevent the primary coil of the micro transformer from burning out, and can also prevent the output voltage from being too high due to excessive load current.

　　When the infrared receiver receives the infrared remote control signal, it outputs a negative pulse, which passes through transistor T1 to the phase, and then forms a pulse width gating circuit through R3 C2, and is input to the pulse input terminal 14 of the IC. The integrated circuit IC is connected to a bistable trigger circuit, and the state of the output terminal ② is flipped once for each input pulse, thereby realizing the on and off control.

　　When the switch is turned off: Pin ② of IC1 is at a low level, the thyristor is turned off, and the load is powered off. At this time, the mains electricity is rectified by the full bridge Q1, and then divided by the resistor R1 to provide low-voltage DC power to the electronic switch, ensuring the supply of standby power.

　　When the switch is turned on, the output terminal of IC1, pin ②, is high level, and the thyristor is triggered to turn on, which is equivalent to the switch being closed, and the load is powered and works normally. If there is current flowing in the load circuit, there must be current flowing through the primary coil of the transformer. After being stepped up by the micro transformer and rectified by the full bridge Q2, it can also provide low-voltage DC power to the electronic switch.

　　It can be seen that no matter whether the electronic switch is turned on or off, the problem of the electronic switch circuit's own power supply can be solved. Every time the remote control is pressed, the state of the electronic switch changes once, thereby realizing the function of the remote control switch.

　　3. Equipment selection and debugging:

　　1. The thyristor, diode and bridge stack in the figure should be selected according to the load current, and the breakdown voltage should be above 400V.

　　2. The micro transformer B1 uses a micro core of EE12 or less. When making it, the number of turns and the turns ratio of the coil can be adjusted to make the secondary output voltage meet the circuit requirements. For example, if the output voltage is required to be 5V, the primary and secondary turns ratio can generally be selected at about 1:10.

　　3. The infrared receiver should use an integrated receiver with negative pulse output. It is best to install a metal shield to improve the anti-interference ability.