Sanitizer - Full Automatic
In the COVID-19 (CORONAVIRUS) pandamic, an automatic Hand Sanitizer is very essential and useful. This Sanitizer may be used at home or office entrance. A 9VDC or 12VDC (500mA) Adapter may be used as power supply for the circuit through the Arduino Uno DC jack.
The basic working of the circuit is, an Ultra-Sonic sensor (HC-SR04) sends signal continuously and checks for any obstruction (say your hand) and sends the pulse based on the distance of the obstruction. If the distance measured is in between 20cm and 40cm, then the Arduino Uno sends the signal to Servo motor (MG995) to operate its shaft. The lever connected to the servo motor shaft in turn pulls the lever of the Sanitizer Bottle, which sprays the liquid available in the bottle. The Nozzle of Sprayer bottle has two options, wide spray or narrow spray by rotating the tip of nozzle to 180 degrees.
Refer full circuit diagram:
Initial Setup / Testing :
Some components, like 7805 (a fixed 5V voltage regulator) and berg strips for easy connections to Servo motor and Ultrasonic sensor are soldered on a general purpose PCB. The connections to the PCB are made such that the berg strip pins are soldered on opposite side of the PCB and matched the pins of Arduino Uno board. So, the PCB may be directly placed on the Arduino Uno board. The servo motor requires up to 400 mA current (at 5V). So, a separate 5VDC power supply is provided through the 7805 IC.
Once the circuit is ready, then the sketch (Sanitizer_USsensor.ino) may be compiled and uploaded to the Arudino Uno board using Arduino IDE.
Now, connect 9VDC (8VDC to 12VDC, 500mA) power supply to Arduino Uno board through its DC jack. Two separate debugging elements are provided on the PCB.
1) TEST BUTTON: To test and adjust the stroke (angle of rotation ) for the servo motor, a Test Button is provided. By pressing the Test Button, the servo motor rotates as per the angle set in the sketch. So, you may adjust the angle or tension of the pulling wire of the lever.
2) SENSOR LED: An LED will glow, whenever the Ultrasonic sensor is sending pulse which matches to the required distance range (set 20cm to 40cm here). The range may be modified in the sketch as per your requirement.
All THE BEST. ENJOY.
FINAL ASSEMBLY : FRONT & BACK VIEWS