Infrared remote control delay switch circuit

This infrared remote control delay switch is made of a small number of common electronic components and is used to control indoor lighting fixtures. It can bring great convenience, especially for families with elderly people and children. This switch has the characteristics of simple circuit, low cost, easy to buy components, small size, reliable operation, strong anti-interference, easy to use, and more importantly, only very low static power consumption. The whole circuit can be installed in an 86-type wall switch. When using it, there is no need to distinguish between the two lead wires. It can be connected in series with various lighting fixtures at will. Just pay attention to the best connection to the AC mains live wire like ordinary mechanical switches.

The circuit is shown in the figure below. The AC mains electricity is converted into pulsating DC power after bridge rectification by diodes VDJ~VD4. One path is directly added to the unidirectional thyristor VS, and the other path is added to the transistor VT1, the integrated infrared remote control receiver TR and the voltage regulator diode VD7 through the resistor R1 and the light-emitting diode LED, and a 5V DC voltage is established on the capacitor C4. Usually, since the IR③ pin outputs a high level, the transistor VT1 is cut off, the corresponding VS is turned off, and the LED lights up to indicate the power supply. ． When any button on the remote control is pressed, the IR③ pin outputs a series of low-level pulses, and VT1 continuously changes from cut-off to on. As a result, vs is triggered and turned on, and the corresponding lamp is powered and illuminated.

Due to the effect of capacitor C2, vs will continue to remain in the on state. Diode VD5 plays the role of increasing the voltage on capacitor C2. After vs is turned on, the corresponding voltage across C2 is measured to be about 1.6V. This voltage charges capacitor C3 through resistor R3. After a certain period of time, the corresponding transistor VT2 is turned on, and as a result, the charge on C2 is released, VS is turned off, and the lamp goes out. According to the values ​​of R3 and C3 in the figure, the measured delay time is 61s. In the figure, C1 is an anti-interference capacitor.

After vs is turned off, the pulsating DC current passes through the resistor R1 and the light-emitting diode LED, and quickly establishes a DC voltage of 5V on the capacitor C4.

There are two types of integrated infrared remote control receiver IR packaging:

One uses iron sheet shielding, and the other uses plastic packaging. Both have 3 pins, namely power supply positive (VDD), power supply negative (CND) and data output (VOUT). The pin arrangement of the infrared receiver head varies depending on the model. The integrated infrared remote control receiver head model used in this article is 557AA51, with pin ① as ground, pin ② as +5V power supply terminal, and pin ③ as signal output terminal. When no infrared signal is received, pin ③ outputs a high level of about 4:2V. When an infrared signal is received, pin ③ outputs a series of low-level pulses. The actual working current is 0.9mA under 5v working voltage. It is precisely because of this infrared receiver head with a small working current that the resistance value of the voltage drop resistor R1 can be larger. As a result, the static power consumption of the entire remote control switch is very small, about 0.4W, which is equivalent to the power consumption of an ordinary small light-emitting diode on a general wiring strip or wall switch. Now we have seen an integrated infrared receiver head with a working current of only 0.5mA, or using a capacitor to drop the voltage instead of R1, which can further reduce the static power consumption of the switch.

Transistor VT3 provides a discharge circuit for capacitor C3. After each delay, VS is turned off, and the 5V power supply voltage established on C4 is added to the base of VT3 through resistors R6 and R7. VT3 is turned on, and the charge on C3 is quickly released to prepare for the next delay. M is a touch metal sheet. When the human body, such as a finger, touches the metal sheet M, the induction signal of the human body can also turn on VT1, and as a result, VS is also turned on, which can also make the lamp energized and emit light into the delay state.

The load of this infrared remote control delay switch is determined by the thyristor vs and VD1. VD5 diodes. vs uses 1A600V, VD1~VD5 uses 1N4007, and the corresponding lamp power is within 100W. VT1 uses 9015, VT2 and VT3 use 9014. VD6 and VD7 use low-power voltage regulator diodes with voltage values ​​of 3V and 5v respectively. The resistance values ​​of R1~R8 are 120kΩ, 2.2kΩ, 220kΩ, 1kΩ, 2.2kΩ, 68kΩ, 39kΩ, and 1.5MΩ respectively, and the power of R1 is 1/2W. The rest are all 1/16W. C1 is a ceramic capacitor with a capacity of 0.1μF. C2, C3, and C4 are electrolytic capacitors, which are 4.7μF, 25V, 470μF, 16V, and 100μ-F, 16V respectively.