control relay with infrared circuit


Posted on Feb 7, 2014

Normally, home appliances are controlled by means of switches, sensors, etc. However, physical contact with switches may be dangerous if there is any shorting. The circuit described here requires no physical contact for operating the appliance. You just need to move your hand between the infrared LED (IR LED1) and the phototransistor (T1). The inf


control relay with infrared circuit
Click here to download the full size of the above Circuit.

rared rays transmitted by IR LED1 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer or else. This circuit is very stable and sensitive compared to other AC appliance control circuits. It is simple, compact and cheap. Current consumption is low in milliamperes. The circuit is built around an IC CA3140, IRLED1, phototransistor and other discrete components. When regu lated 5V is connected to the circuit, IR LED1 emits infrared rays, which are received by phototransistor T1 if it is properly aligned. The collector of T1 is connected to non-inverting pin 3 of IC1. Inverting pin 2 of IC1 is connected to voltage-divider preset VR1. Using preset VR1 you can vary the reference voltage at pin 2, which also affects sensitivity of the phototransistor. Op-amp IC1 amplifies the signal received from the phototransistor. Resistor R3 controls the base current of transistor BC548 (T2). The high output of IC1 at pin 6 drives transistor T2 to energise relay RL1 and switch on the appliance, say, hand dryer, through the relay contacts. The working of the circuit is simple.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Soft Start for PSU
    LED operates as light sensor
    Automatic-video-switch
    Receiver Frequency-Converter Stage
    Precise One Shot Circuit
    20- 40W electronic ballast principle and maintenance
    50W car audio amplifier schematic circuits
    automatic water tank filler circuit diagram
    Car battery charger
    Electronic fishing shrimp machine circuit diagram 2
    Servo CDI Programmable Digital Ignition
    MCU power supply wiring portion



    Top