automatic sanitizer dispenser, using ir sensor, relay, water pump

Automatic Sanitizer — Apparatus Required and Principle of Working

The circuit shown uses an IR proximity sensor, relay module, DC pump/motor, and two 9 V batteries to operate a sanitizer dispenser automatically.

Apparatus required

1. IR obstacle/proximity sensor module – 1
2. Relay module – 1
3. DC mini water/sanitizer pump or DC motor – 1
4. 9 V batteries – 2
5. Battery connectors – 2
6. Connecting wires/jumper wires
7. Sanitizer container
8. Plastic tube/nozzle for dispensing sanitizer
9. Switch – optional
10. Small enclosure/frame to mount the components

Principle

The automatic sanitizer works on the principle of infrared (IR) detection.

The IR sensor continuously emits infrared radiation. When a person’s hand is placed near the sensor, the IR radiation is reflected back to the receiver. The sensor detects this reflected radiation and changes its output signal.

This output activates the relay. The relay acts as an electrically operated switch and supplies power to the DC pump/motor. The pump then draws sanitizer from the container and sprays/dispenses it through the nozzle.

When the hand is removed, the sensor output changes back, the relay switches OFF, and the pump stops.

Working

Step 1 – Detection:
The IR sensor continuously monitors the area in front of the sanitizer dispenser.

Step 2 – Hand detection:
When a hand is brought close to the sensor, the IR light is reflected from the hand and detected by the sensor.

Step 3 – Relay activation:
The sensor produces an output signal that activates the relay module.

Step 4 – Pump operation:
The relay closes its contact and connects the second 9 V battery to the DC pump. The pump starts rotating.

Step 5 – Sanitizer dispensing:
The pump draws sanitizer from the container and pushes it through the tube/nozzle onto the user’s hand.

Step 6 – Automatic stopping:
After the hand is removed, the sensor output changes, the relay turns OFF, and the pump stops automatically.

Block diagram

Hand → IR Sensor → Relay → DC Pump → Sanitizer Dispensed

Important note about your circuit

In the diagram, the first 9 V battery is used for the sensor/relay control side, while the second 9 V battery supplies the pump/motor through the relay contacts. This arrangement keeps the motor’s higher current demand separate from the sensor circuit.

Also, check the voltage rating of your particular relay module and pump before connecting the batteries. Do not assume every relay module or pump is suitable for 9 V.