Arduino based HAND WASH Timer

My name is Santosh, I have made a hand wash timer using Arduino. The purpose is to help to remind ourselves to wash our hands for at least 20 seconds. We’re calling the project Go Corona, and I’m sharing the tutorial so that anyone can make it by themselves. This project is for everyone.

WHO recommends to wash our hands with soap for at least 20 seconds. But it is difficult to trace the time during washing hands. So, here I have come with this Non-Contact Hand Washing Timer.

Benefits of Hand Wash Timer (Go corona)

  • The entire system is automated and contactless.
  • Instantly ready for the second user.
  • Requires minimum cost.

Material required

SG-90 Micro Servo1
Arduino Uno1
HC-SR04 Ultrasonic Sensor1
Jumper wires1
hand wash3.png
Wire diagram for hand wash timer

Wiring Steps

Wire up the sensor and servo according to the wiring diagram attached below.

ultasonic sensor

VCC -> 5V on the Arduino

hand wash timer

Trig -> Pin 9 on the Arduino

hand wash sink

Echo -> Pin 10 on the Arduino

arduino ultasonic

GND -> GND on the Arduino

hand wash sink

For the Servo Motor, use the Male\Male wires to connect the following-

Red Servo Wire (5V) -> Vin on the Arduino

hand wash sink

Black Servo Wire (GND) -> GND on the Arduino

Orange Servo Wire (Signal) -> Pin 7 on the Arduino

hand wash sink

Assemble the Timer

And cut out a servo sized hole

Note: You can also check out the video for a step-by-step wiring guide.

Open the Arduino software
Make sure to install the NewPing, EWMA, and Queue libraries from the Arduino library manager before running to the sketch!

Download Code

Alright, it’s time to get your hands washed! Place your Go Corona to the sink and tape the ultrasonic sensor around the rim. 

The ultrasonic sensor works by sending out ultrasonic sound waves and measuring how long it takes for them to return. If the sensor is receiving reflections from things that aren’t hands in the sink, it may trigger the timer unnecessarily.

Warning: Electronics and water don’t mix! So, think about the location of your Arduino.

Once the sensor is in a good position, plug the Arduino into a USB wall adapter nearby. The servo should sweep back and forth, indicating the timer is active.

Try washing your hands and see if the countdown starts, then its working well.

hand wash near me

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