We are a noted Manufacturer and Supplier of Infrared Remote Switch Circuit in India. The circuit described here can be used for any simple on/off function such as controlling a lamp or fan. The major advantage is that this circuit is absolutely free from ambient light interference and provides controlled range of about 10 mt without the use of any focusing lens. Transmitter and receiver circuits are described below:
Transmitter Circuit :
Transmitter section consists of a power supply, an oscillator and an output stage. The circuit diagram for transmitter is shown in fig. IC1 is wired as an astable multivibrator with a center frequency of about 26 KHz. When switch S1 is pressed, the circuit gets energized, output of IC1 is a square wave. The infrared LED connected at its output transmits IR beams modulated at the same frequency. The oscillator frequency can be shifted slightly by adjusting preset VR1.
Receiver Circuit :

• Receiver section comprises power supply an infrared detector module, time delay circuit with noise filter, bistable flip-flop and an output section. The IR signal from the transmitter is sensed by the sensor and output at pin 2 goes low. This in turn switches on transistor T1. Consequently, capacitor C8 starts charging through resistor R5. When voltage across capacitor C8 reaches about 3.5V, IC2 receives a clock pulse at pin 14 and its output at pin2 goes high. As a result T2 becomes on, whish energizes relay RL1. The output of IC2 is also used for lighting the LED D5 indicating the presence of a signal.
• When ON signal is available output of sensor goes high and T1 is switched OFF. Now capacitor C8 starts discharging through R6 and voltage across it decreases to zero. When another signal arrives after about 300miliseconds capacitor C8 again charges through R5 and IC2 gets another clock pulse. But its reset through diode D4, the output at pin2 toggles.
• If another pulse arrives from the transmitter before a delay of about 300ms, T1 again turns ON and voltage across C8 cannot fall below 1.5V i.e. maximum input voltage required to sense a logical low by IC2. Hence, the output of IC2 does not change. This feature prevents false triggering. R5, C8 network provides immunity against IR noise. IC3 is a regulator IC that provides a regulated voltage.

Protect the circuit :
High frequency produces a lot of harmonics act as a source sustained noise. To minimize this effect, the sensor should be covered with a dark red glass plate light from other sources like fluorescent lamps. IR candescent lamps and sunlight do not have any effect on the circuit.
Calibration :

• If LED D5 does not glow, adjust preset VR1 till it glows. Gradually increase the distance and fine-tune the preset for maximum range.
• ON/OFF switch by remote from 10mtr distance.

We are a noted Manufacturer and Supplier of Infrared Remote Switch Circuit in India. The circuit described here can be used for any simple on/off function such as controlling a lamp or fan. The major advantage is that this circuit is absolutely free from ambient light interference and provides controlled range of about 10 mt without the use of any focusing lens. Transmitter and receiver circuits are described below:
Transmitter Circuit :
Transmitter section consists of a power supply, an oscillator and an output stage. The circuit diagram for transmitter is shown in fig. IC1 is wired as an astable multivibrator with a center frequency of about 26 KHz. When switch S1 is pressed, the circuit gets energized, output of IC1 is a square wave. The infrared LED connected at its output transmits IR beams modulated at the same frequency. The oscillator frequency can be shifted slightly by adjusting preset VR1.
Receiver Circuit :

• Receiver section comprises power supply an infrared detector module, time delay circuit with noise filter, bistable flip-flop and an output section. The IR signal from the transmitter is sensed by the sensor and output at pin 2 goes low. This in turn switches on transistor T1. Consequently, capacitor C8 starts charging through resistor R5. When voltage across capacitor C8 reaches about 3.5V, IC2 receives a clock pulse at pin 14 and its output at pin2 goes high. As a result T2 becomes on, whish energizes relay RL1. The output of IC2 is also used for lighting the LED D5 indicating the presence of a signal.
• When ON signal is available output of sensor goes high and T1 is switched OFF. Now capacitor C8 starts discharging through R6 and voltage across it decreases to zero. When another signal arrives after about 300miliseconds capacitor C8 again charges through R5 and IC2 gets another clock pulse. But its reset through diode D4, the output at pin2 toggles.
• If another pulse arrives from the transmitter before a delay of about 300ms, T1 again turns ON and voltage across C8 cannot fall below 1.5V i.e. maximum input voltage required to sense a logical low by IC2. Hence, the output of IC2 does not change. This feature prevents false triggering. R5, C8 network provides immunity against IR noise. IC3 is a regulator IC that provides a regulated voltage.

Protect the circuit :
High frequency produces a lot of harmonics act as a source sustained noise. To minimize this effect, the sensor should be covered with a dark red glass plate light from other sources like fluorescent lamps. IR candescent lamps and sunlight do not have any effect on the circuit.
Calibration :

• If LED D5 does not glow, adjust preset VR1 till it glows. Gradually increase the distance and fine-tune the preset for maximum range.
• ON/OFF switch by remote from 10mtr distance.