Introduction: Simple Contactless Hand Disinfector / Soap Dispenser

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I have designed an contactless desinfector using a 9 gram servo, ultrasonic proximity sensor and arduino nano. The mechanism is very simple using only a string to push down on the cap of the hand sanitizer.

Step 1: Tools and Parts


- 3D printer

- Solodering iron

- Small cross tip screwdriver

- Ca glue



- Arduino nano

- 9g servo

- Ultrasonic Sensor HC-SR04

- Toggle swich

- wire

- 3 pin header

- small protoboard

- non elastic thin string

- round hand sanitizer

- li-po battery (optional)

-5V boost circuit(optional)

Step 2: 3D Printing the Enclosure

3D printing parts are avalible here.

For 3D printing the model needs to be split into two parts and parts need to be aligned the biggest surface down for the best printing results. (the model already consist of two parts).

Step 3: Inserting the Servo

Before gluing the two parts together you must first screw in the servo using the inclded screws.

When attaching the servo lever pay attention that the servos upper end point stops before hitting its oppening.

After attaching the servo, you can glue the two parts together using ca glue or other preffered glue for gluing 3D printed parts.

At last run the servo cable through the side hole.

Step 4: Inserting the Proximity Sensor

Insert the proximity sensor in the front by sliding it in and pushing it in the holes.

If you want you can solder some wires on its pads or you can just use the standard jumper wires.

Run the wires through the side hole.

Step 5: Solder the Electronics Together

Solder the 3-pin header to the protoboar and connect 5+ and GND terminafrom the protoboard to the arduino and to the proximity sensor and the servo 3-pin header. (and to the output of the boost regulator if you are using a battery for power supply).

You need to connect the trigger and echo pins from the proximity sensor to digital pins 11 and 10.

From the 3-pin header solder the servos signal pin to the arduinos digital pin 9.

If you are not using the battery for power supplay the circuit will be powered by the arduinos usb connector.

Step 6: Insert the Electronics and Upload the Code

After soldering all the wires you need to put the electonics in the bottom of the dispenser.

Run the USB cable through the side hole and upload the code to the Arduino.

You can find the code here.

Step 7: Finishing Up

Now you need to insert the hand sanitizer bottle in the holder and run the string from the servo lever over the bottle press cap to the hook on the other side.

Tip: To prevent the string from sliding of the cap you can cut small notches on the side of the cap.

You can do the same on the servo side by using a linkage stopper or small pice of a push rod.

Step 8: Finished

Now the Automatic hand sanitizer is ready to use!

Stay safe and healthy!

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