Wireless Light Switch Circuit

light electronic switchYou may use this wireless light switch instead of physical contact with switches which may be dangerous if there is any shorting. The wireless light switch 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 IR rays transmitted by IR LED1 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer etc.

This wireless light switch 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.

The working of the circuit is simple. In order to switch on the appliance, you simply interrupt the infrared rays falling on the phototransistor through your hand. During the interruption, the appliance remains on through the relay. When you remove your hand from the infrared beam, the appliance turns off through the relay.

Schematic of the electronic wireless light switch circuit


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  • jai

    thank you for this circuit and it is working very fine.but 5v relays are not available at my place,only 12 v relays are available please help me to convert this circuit to 12 v circuit.

    thanking you in advance

    • Yogi


      Just add regulator from the power. 7805 regulator is enough.
      the relay direct connect to the power. but the output 5 volt is connected to the circuit.
      I think that all.

  • Madhu

    I would like to know what u would connect across the load?? it the component itself for example bulb or u need a transformer?

    • Yogi

      Means of load is any load. motor, bulb, fan, etc.
      it just switch. you can switch anything by this switch.

  • Yogi

    Basically it’s simple schematic.
    it’s like a proximity censor.
    the switch has changed by infrared transceiver. isn’t it?
    I think it’s easy to understand.
    transmitter is LED as an infrared
    and the receiver using photo transistor.

    Good article

    Thanks a lot

  • sharik

    has anyone tried this………have u got d output….???

  • huda

    thanks buddy..

  • huda

    hay,pls anyone could give more information about D1 1N 4007,and ps explain diagram in detail..
    pls this is about my project..

    • Jim Keith

      This is called a free-wheeling diode, or commutation diode. paras raval has it correct except for the spelling.

      When transistor T2 turns off, the current flowing through RL1 relay coil continues to flow in the same direction and can generate destructive voltage. Since the coil is now the current source (rather than the power supply), the polarity of the voltage across the coil reverses and the current flow (free wheels) through D7 until it decays to zero. When the current drops to about 20%, the relay drops out.

      “Free wheeling” is a term borrowed from some early automobiles that automatically disengaged the transmission when coasting down hills. While an energy saving feature, it placed all speed limiting upon the brakes and/or air resistance, and tended to be dangerous.

      The expression “commutation diode” comes from SCR inverters, where SCRs are force commutated (turned off) via reverse biasing the device. In this case, the reverse voltage is clamped via an anti-parallel diode for a short period of time (perhaps 50uS) until the SCR electron carriers are cleaned up.

      Most silicon diodes will work for this application –1N914, 1N4148, 1N4002,3,4,5,6,7. Even a properly sized resistor connected across the coil can prevent the voltage from becoming excessive.

    • paras raval

      D1 1N4007 is a rectifier diode, here it work to reduce free wellington effect.

  • pavani

    plzzzz send documentation on wireless switch plz send as early as possible


    plz give me the full details of this circuit and also tell how to add a timer to it this ..

  • paras raval

    i think in this ckt we add flip-flop so that one time we interrupt IR the appliance ON & 2nd time interrupt IR the appliance OFF. is it so?

  • harsha

    i want connections for wireless switch plz its urgent ! on BREAD BOARD can u give a video on this?

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