Touchless Water Tap using IC LM358

Circuit Design:

1. LM358 Connections:
   • Connect the VCC pin (pin 8) of the LM358 IC to the positive supply voltage (e.g., 12V).
   • Connect the GND pin (pin 4) of the LM358 IC to the ground (0V) of the circuit.
2. Proximity Sensor:
   • Connect the output of the infrared (IR) proximity sensor module or ultrasonic sensor to the non-inverting input (pin 3) of the LM358.
   • Connect the sensor’s VCC and GND pins to the positive supply and ground, respectively.
3. Voltage Divider:
   • Create a voltage divider using two resistors (e.g., 10kΩ and 100kΩ).
   • Connect one end of the 10kΩ resistor to the positive supply voltage.
   • Connect the other end of the 10kΩ resistor to the inverting input (pin 2) of the LM358.
   • Connect the junction between the two resistors to the inverting input (pin 2) of the LM358.
   • Connect the end of the 100kΩ resistor to the ground.
4. Output Stage:
   • Connect the output (pin 1) of the LM358 to the gate or base of a power MOSFET or relay.
   • Connect the source or emitter of the power MOSFET or relay to the ground.
   • Connect the drain or collector of the power MOSFET or relay to the positive supply voltage through a diode (e.g., 1N4148) to protect against voltage spikes.
5. Water Pump or Solenoid Valve:
   • Connect the water pump or solenoid valve to the common terminal of the power MOSFET or relay.
   • Connect one side of the water pump or solenoid valve to the positive supply voltage.
   • Connect the other side of the water pump or solenoid valve to the ground.

Working Principle:

• The LM358 is used to amplify the signal from the proximity sensor.
• The voltage divider sets a reference voltage for the inverting input.
• When a hand is detected by the proximity sensor, the output of the LM358 changes, triggering the power MOSFET or relay.
• The activated power MOSFET or relay turns on the water pump or solenoid valve, allowing water flow.