Twinkle, Twinkle, Little Soap Dispenser

January 21, 2011

Most people do not wash their hands  properly. Many sources say that you should scrub your hands for at least 15-20 seconds. A good way to keep track is to sing a song like Twinkle, Twinkle, Little Star.

Here is a Lysol LYSOL® Healthy Touch® No-Touch Hand Soap System that has been modified using Arduino to show a countdown and play Twinkle, Twinkle, Little Star.. 

Here are the parts you will need.

  • LYSOL® Healthy Touch® No-Touch Hand Soap System
  • Aruino Uno
  • NPN transistor
  • 3x 330 Ohm resistors
  • 2x 1k-10k Ohm resistors
  • 2 7-segment displays
  • 24-gauge solid core wire
  • perfboard

 Disassemble the soap dispenser. There are three screws on the bottom and four screws in the battery compartment. Once you take them out, you should be able to take off the bottom and access the circuit board

Cut off all the wires from the board. Solder some solid core wires to the IR receiver.

Cut the traces for the IR receiver on the back

Now, lets take a look at the schematics.

Here is the schematic to hook up the parts.

First let's make the display. Wire segments a-g from both displays together and then wire them to Digital0-Digital6. Take a resistor to each common cathode and wire them to Digital7 and Digital8. Here is what the display will look like

You can see the resistors for both of the displays.

For the other resistors and the transistor, we use another piece of perfboard.

Now finish the wiring and hook it up to the Arduino. Now time to program the Arduino.

You should now have something that look like this

Now it's time to program the Arduino. Download the source code from below.

Click Here For Source Code

Change the pins in the program to match what you hook them up in the Arduino.