We all have to wash hands every now then to get rid of the virus and bacteria specially for Corona virus we need to wash our hands for 20 seconds to completely get rid of it. Also the soap dispenser or the tap knob may not necessary be hygienic or clean and its the first and last thing we touch while cleaning our hands. Also the water keeps on running these 20 seconds while we are still rubbing our hands with soap.

This project overcome these two problem

1- Hygiene

2- water wastage

by providing a cheap automatic solution

Step 1: Measurments

Note the shape and measure the tap knob size, diameter and note it down. Also measure the height of the knob from top of basin and note it.

Step 2: CAD Design

Make your CAD design using previous noted measurements. I used ThinkerCad.

Do make sure to make the cad design few mm bigger in diameter because it has to fit on top of the knob.

Also design and print the frame it can be very simple cuboid stick, its just for support.

Now save/download the .stl file.

open it in your preferred slicer and slice it. I used creality-cura slicer.

you can download my .stl file and play around

Tap Knob couple.stl
Download View in 3D

Step 3: 3D Printing

3D print your CAD model and clean it using some sandpaper. Specially from the inside to same smooth contact with the Tap knob.

Step 4: Knob Assembly

Now carefully align the servo head with the center of axis of knob rotation depending on your knob shape and size it may vary, mine is cylindrical so its the center point.

Now take super-glue and stick it in its position carefully.

Also test it by putting the head back on the servo and rotating it manually.

Step 5: Wiring

Connect the Arduino board to computer/laptop and connect as shown in wiring diagram

below is the code for the program you may need to change servo rotating parameters(in degrees and clockwise or anti-clockwise) according to your tap knob rotation.

you can also download directly the ino file given (Arduino ide).

code is as follows:-

#include
Servo myservo; const int buttonPin = 2; // the number of the pushbutton pin int buttonState = LOW; void setup() { // put your setup code here, to run once: myservo.attach(9); // attaches the servo on pin 9 to the servo object pinMode(buttonPin, INPUT); }

void loop() { buttonState = digitalRead(buttonPin); // put your main code here, to run repeatedly: // check if the pushbutton is pressed. If it is, the buttonState is HIGH: if (buttonState == HIGH) { myservo.write(190); // tell servo to go to position in variable 'pos' } buttonState = digitalRead(buttonPin); if (buttonState == LOW){ myservo.write(10); // tell servo to go to position in variable 'pos' } }