IR Controlled Water Supply

This article is about IR controlled Water Supply, which is simple to build. This circuit is used in Restaurants and homes at automatic water supply or flush. Lets take one scenario to understand clearly. Automatic water supply will turn ON when you place hands ahead of a tap. When you remove hands, water supply will turn OFF. Let’s see furthermore about this circuit.

IR Controlled Water Supply Circuit

ir controlled water supply

Parts Required


  • IC1 7805
  • IC2,IC3 555


  • T1,T2,T3 BC548


  • R1 2.2K Ohm
  • R2 1K Ohm
  • R3 47 Ohm
  • R4 100 Ohm
  • R5 2.7K Ohm
  • R6 100K Ohm
  • R7 10K Ohm
  • Variable Resistor 20K Ohm


  • C1 10u,10V
  • C3 0.001u
  • C4 0.1u
  • C5,C8 100u,16V
  • C6,C7 0.1u
  • C9 10n


  • IR LED
  • TSOP 1738
  • 5V Relay
  • Solinodal Valve
  • Switch
  • Battery
  • 1N4001 Diode


IR Controlled Water Supply Circuit Working

IC1 7805 regulates the 9V DC power supply to 5V DC. IC2 is a 555 IC, which acts as an oscillator. IC2 will generate the digital pulse with 38kHz at pin 3. This IC2 is configured in Astable multivibrator mode. The digital pulse generated is fed to T1, when the pulse is high it connects the ground to IR LED and when the pulse is low acts as an open circuit. Here T1 acts as the switch for IR LED.

The TSOP 1738 is an IR receiver of 38kHz, it will receive IR signals of 38kHz. When TSOP 1738 receives the IR signal, it switches the T2. It leads to generate a single digital pulse by IC3 which was configured in Monostable mode. The time period of this pulse will be the time till you receive IR signal. The pulse generated is fed to transistor T3. Here T3 acts as a switch and connects ground to Relay RL1 to turn ON the relay. When the relay turns on it will turn ON the solenoidal valve and releases water.

The transmitter (IR LED) and receiver ( TSOP1738) has to be placed at the tap. When the hand is placed at the tap, IR signal generated by IR LED will hit the hand and reflects back to the IR receiver.


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