Logic for dispenser Circuit:

1. The module will keep the pump off until the hand is detected by sensor.
2. When the sensor detects hand, the module will switch on the pump and the pump remains on until time expires (this time is set using potentiometer).
3. Once the time expires, the pump will remain off even if the hand is below the sensor, this will prevent the over dispensing of sanitizer.
4. When the sensor detects hand, the module will switch on the pump and if the hand is removed before the time period set by the user, the module will switch off the pump as soon as the hand is removed, preventing wastage for sanitizer.Example:Consider Module time is set to 2 seconds using an on_time potentiometer.

Case 1: Hand is kept below the sensor and pump starts, but the user didn’t remove the hand for next 4 seconds then

Operation:
The module will switch on the pump as soon as the hand is detected and keep the pump on for 2 seconds, then the module will switch off the pump and keep the pump off until hand is removed. Hence preventing over dispensing of sanitizer. Next time, when the hand is again detected pump will start and the same logic is implemented.

Case 2: Hand is kept below the sensor and the pump starts, but the user removes the hand after 1 second only.Operation:
the module will switch on the pump as soon as a hand is detected and keep the pump on for 1 second, but as soon as it detects the hand is removed, it will switch off the pump. Hence preventing the wastage of sanitizer