Introduction: Touchless Dog Hand Wash Timer (Made in Fusion 360)

About: I like to design something in 3D model.

COVID-19 makes us devastated, especially we should consider making our living cleaner and more sanitized than before. CDC always recommends us to wash our hand regularly and properly that can save our lives. The CDC guideline for good washing hands is that we should scrub our hands for about 20 seconds. For more information from the CDC guideline, click here. There are so many projects out there regarding touchless simple machines to help us combat this pandemic. In this challenge, I want to present a touchless hand wash timer combining with lights, music, and a creative enclosure that made my family and me delighted to use it.

This project is so simple to make and use. When we wave our hand in front of the ultrasonic sensor, it will turn on the light, start from green, and end with red. Moreover, to make this hand wash timer more interesting and fascinating is that I add a jingle that will sing to you for about 20 seconds in accordance with the CDC guideline. Actually, CDC recommends using Happy Birthday jingle for scrubbing our hands. We can change the jingles with any music as we desired and program it, so it will have a 20-second duration of jingles. Since my favorite animal is sheep, I used "Baa Baa Black Sheep" jingles for my hand wash timer.

This fall I am an 8th grader, who studies online schooling. You can find my enclosure design in Thingiverse and myminifactory. For the code, you can find in my blog.


Materials and tools that we need for this project:

Arduino Nano

Ultrasonic sensor

6 LEDs (1 green, 2 whites, 1 yellow, 1 blue, and 1 red LED)

Speaker (you can use whatever speaker you have or Piezzo buzzer. I used a speaker from my old and unused headset)

Battery holder (for 3 AAA Batteries with built-in switch)

3 AAA Batteries

Small Perf board (2 x 8 cm)

Large Breadboard and jumper wire male to male (for prototype)

3D Printer and slicer

PLA Filament (Green and red)

Foam for the speaker (actually you do not have to do this. My speaker's foam was torn out when I do some trimming in speaker, so I add another foam to cover the speaker)

Electrical Wires

Electrical tape

Solder wire

Hot glue

Phillips Oval Head Tapping Screws (4 pcs)

Spray Paints (Green and red)


Soldering gun

Desoldering pump

Makita Drill

Drill Bits

Philips screwdriver


Dremel Sander

Iron Hacksaw

Vise jaws

Double tape

Step 1: Wiring and Schematic

This is the whole idea for this project. We will connect Arduino Nano with an ultrasonic sensor, speaker, LEDs, and battery holder. The ultrasonic sensor has 4 legs in it. Connect Trig to D12 pin Arduino Nano. Echo leg is connected to D11pin Arduino Nano. VCC connects to 5V Arduino Nano. Gnd connects to the Ground pin in Arduino Nano. Then, connect the positive leg of the LED with Arduino Nano. Here are the breakdowns of the connecting wire:

Green LED connects to D7 pin Arduino Nano.

White LED1 connects to D6 pin Arduino Nano.

White LED2 connects to D5 pin Arduino Nano.

Yellow LED connects to D4 pin Arduino Nano.

Blue LED connects to D3 pin Arduino Nano.

Red LED connects to D2 pin Arduino Nano.

Connect the negative leg of LED to the ground pin in Arduino Nano. Wiring the speaker with a red wire as positive and black wire as negative. The positive wire of the speaker is connected to D8 pin Arduino Nano and the negative wire is connected to the Ground pin in Arduino Nano. Lastly, connect the components with a power source. Here, I used 3 AAA Battery with the battery holder and built-in switch. Connect the positive to Vin in Arduino Nano and negative to ground in Arduino Nano.

For your information, there are two pins of ground in Arduino Nano. You can use ground pin in digital and analog either way.

Here is the image of schematic for the project that I made in Fritzing.

Step 2: Understanding Code

Of course you will need some codes to make this project work. For viewing the code, you could download the code in my Blog. But you should download the pitch library as well.

First, we should define the echo and trig pins in Arduino Nano.

int echoPin = 11;
int trigPin = 12;

We set up the pin mode for trigPin and echoPin as output and input, respectively.

void setup() {
  for (int i = 2; i <= 7; i++) {
    pinMode (i, OUTPUT);
  pinMode (trigPin, OUTPUT);
  pinMode (echoPin, INPUT); 

Create the loop to order the Ultrasonic Sensor to measure distance and reads the measured data. If the distance is 15 cm, hand wash timer becomes triggered.

void loop() {
  digitalWrite(trigPin, LOW);
  digitalWrite(trigPin, HIGH);
  digitalWrite(trigPin, LOW);
  durationus = pulseIn(echoPin, HIGH);
  distance = (durationus * .0343) / 2;

  // This condition is to determine an object with a distance of 15 centimeters.
  if (distance > 0 && distance <= 15) {ledmelodytimer();}

For the jingle, I searched the notes of Baa Baa Black Sheep song on Pinterest. See the image. The left side is the ordinary note of the song that I searched from this source. On the right side, I input the notes as listed in the pitch library. The pitch library contains notes from C4 until C7. I choose #4 for the octave. The greater the number of octaves is, the higher the pitch is. It is entirely up to you to choose the octave. You can play around to create different pitches of the jingle. For note duration, I used the number of 2, 4, and 8, which meant half-note, quarter-note, and eighth-note, respectively. You can change the jingle as you like.

Step 3: Project Prototype

It is time to make a prototype for the project to make sure the project succeeds smoothly. I used large breadboard and jumper wires male to male to connect Arduino Nano with other components because it is very easy to make this without soldering. But before connecting with a power source of battery, it is better to use a power source from a computer. By using a USB cable, connect the prototype with the computer. Upload the code.

Step 4: How It Works

The global idea for this hand wash timer is that when your hand is waving in front of the ultrasonic sensor, it will lighten the LED on, start from the green LED, and ending with the red LED. At the same time, it will sing a jingle for a duration of 20 seconds. After succeeding in downloading the code, it is time for testing with the battery power source.

Step 5: Enclosure

We will make the enclosure for this project. Before connecting and soldering, I prepared the size of the enclosure overall. To make this, I used Fusion 360. For the easier enclosure, I searched on Google for the dog silhouette image. Save it in .jpg or .png file. Convert the image to .svg file. I used this converter.

Step 6: Sketch

Insert the SVG file into Fusion 360 by clicking the insert tab and choose to insert SVG. Before you can insert your SVG file, you should choose the plane first. After that, select your file and if you are satisfied, click ok. Now you have a dog sketch in your sketch area. Next, finish the sketch.

Step 7: Extrusion

Extrude the sketch for 50 mm and choose the operation to new body.

Step 8: Scaling

Because the overall sizes (for x and y) are too small, just scale it with the scale factor as you desired. For the resize is just for x and y (length and width), so select the scale type to non-uniform and input the scale for x and y scale, where the z scale remains the same.

Step 9: Shell

Shell the inner of the model. Choose the inside direction and input the thickness as you desired. Mine is 5 mm. Click ok.

Step 10: Details-Tongue

For creativity, add some details to the model, such as tongue, eyes and mouth. To create tongue, use form and select box. Play around with the form until you form a tongue model.

Step 11: Details- Eyes

You need to make a hole for the eyes. Later, we want to make eyes out of an ultrasonic sensor. For doing this, use a sketch and make two circles by using center diameter circle with a diameter of 17 mm and the distance between two circles is 10 mm. Finish the sketch. Extrude it by selecting a cut operation.

Step 12: Details- Mouth

Do the same as the previous step for creating the mouth. The only difference is that we only need one circle and the diameter is bigger than previous ones. For this diameter, you need to measure your speaker's diameter. I used 44 mm for the diameter. Finish the sketch and extrude it with the cut operation.

Step 13: Details- for the Screws

You have to make rooms for holding the screws. For this, just make circle sketch and attach to the body. Make sure you have to measure how big your screws are. See the pictures. I made four rooms for holding the screws.

Step 14: Stand

We have to make stand, so the model is more stable. Make rectangle in the sketch and extrude it. Make sure the rectangle should attach to the model.

Step 15: Back Part

For the back part, make a copy from the front part, but remove all the holes.

Step 16: Hole for Battery Holder's Cable

Make a hole in the back part for battery holder's cable by creating circle in the sketch. Extrude it by using the cut operation.

Step 17: Finish Modeling

Now it is time to rendering the model. I choose green painting color for the all the body and red for the tongue. You are finished creating your enclosure.

Step 18: Printing

Save the model to STL files and export it. You should have 3 bodies for this model, which are the front part, back part, and tongue. Print it. For printing the front and back parts, I used 0.2 mm of layer height, 20% infill, no raft and without support. For printing the tongue, I used 0.2 mm of layer height, 20% infill, brim and support with density of 12 %. Total printing is about 11.5 hours and spent about 53.5 meters long of PLA filament.

Step 19: Polishing After Printing-1

After printing, we should polish it because the printing result is not so smooth. Fill the gap with wood filler. Wait until it dry. Sand it with sandpaper and Dremel Sander until all the surfaces are smooth.

Step 20: Polishing After Printing-2

Then, paint it with spray paint. I used green color. You can choose your color as you like.

Step 21: Trim the Speaker

Speaker is too big to place inside the enclosure. I trimmed it by using iron hacksaw. The result of this trimming is that the speaker's edges are too sharp, so I smooth it with Dremel sander.

Step 22: Preparation of Soldering

Collect all the components for this project. See the picture. Solder wires to the speaker.

Step 23: Wiring the Component-LEDs

First, we need to connect all the LEDs. To make it simple, I used a small perf board (2 x 8 cm). Arrange the LEDs into one straight line with green, white, white, yellow, blue, and red LEDs in order. Solder the LEDs to the perf board and connect the negative legs together. Solder each of positive legs of LED to electrical wire one by one. Test the LEDs first by using coin cell battery CR2032 for each LED to make sure all LEDs work.

Step 24: Holes for LEDs

Measure the holes and mark it. By using Makita drill, drill six holes for LEDs in the enclosure. Smooth the rough edges.

Step 25: Holes for Screws

By using Makita drill, drill four holes for screws in the back part of enclosure.

Step 26: Wiring the Component

Connect the positive legs of LEDs to Arduino Nano. Then, connect Arduino Nano with the ultrasonic sensor. Lastly, connect speaker and battery holders to the electrical circuit. See the connection as I mention previously or you could see my schematic above. Mount every component to the enclosure properly. Tidy the wire. Make sure before connecting the battery holder, you should insert the cable of the battery holder to the hole in the back part.

Step 27: Close the Enclosure

Close the enclosure with Phillips oval head tapping screws one by one. Glue the battery holder to the enclosure.

Step 28: Assemble Tongue

Finally, glue the tongue to the enclosure.

Step 29: Finish Project

Here is the finish project of my touchless hand wash timer.

Step 30: Testing

At last, test it. The project is a complete success. My hands are super clean, but you should not keep the water running while washing hands. This project is a great project to teach kids how important to keep clean and wash hands properly.

I hope you like my instructables. Thank you for reading this. I really appreciate it.

For more project ideas, click: 3dPrintingCenter

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"Can't Touch This" Family Contest