It’s during times like these that inspire innovation. I even made something for the cause!


In that spirit, the “Fighting Germs” contest is here to not only reward that innovation ─ but also give to other charities for those attempting the same thing! It’s fun, it’s beneficial.


They say the best time to plant a tree is thirty years ago. The next best time is today.




Washing your hands for 20 seconds will destroy the Covid-19 virus.


Wow, is counting to 20 gets boring after a while. Also, I find my counting is somewhat inaccurate. Especially when I want to go do something else.

So, I thought a visual timer that would countdown every time I put soap on my hands would be a better option. To curb the tedium with this, I also wanted the countdown to be different looking ever time.


Being in a social distancing environment, lockdowns, etc.… I had to cut a few corners in the construction of the soap dispenser actuator. My shop is challenging to get to.

Behold my ingenuity… I placed a soap pump on a big button! It works too!


How the system works:

Once the Micro:bit is powered, you can set the time it takes to erase the image on the device’s LED screen. The screen is a 5x5 LED matrix if you don’t already know. Press the “B” button to increase the time.

There will be an image placed on the screen. I used a variety of images already in the Library. The system waits for a button press.


The soap dispenser would be placed on a very sensitive button. In my project, I ended up using a button I salvaged from a demolished factory. In my original plans would have been a contact switch with a travel of a micrometer. However, my salvaged button travels about 2.54 cm (an inch). I give it a gusto press, and the sequence starts.


A spiraling dot will erase the image and flash the screen with a square. You’re done washing!

It will reset to the next image and wait.



First, let’s gather all the necessary components you’ll need to build this project.

1x BBC Micro:bit

1x Kitronik Inventor’s Kit (This is mainly for the breakout adapter and project wires.)

Project Wires Female - Male

1x Momentary Contact Button


For the momentary button - I am thinking a foot pedal push button might be a good option for simplifying this project. You can then put any soap bottle on the button and use it. The one I selected here is watertight. Might work out.



Load the code onto the Micro:bit.

I am providing the hex file you need to drag and drop onto the Micro:bit, and the python code as two separate files. For the below process, just use the hex file.

Plug the MicroUSB cable into the Micro:bit, and plug the other end of the cable to a PC or MAC.

At this point, you are going to copy over the code to the Micro:bit. I am providing the program (code) in this post that needs to be copied over. When the Micro:bit plugs into a computer, it shows up as a USB flash drive. All you have to do is copy the file over to the Micro:bit, like it’s a USB Flash Drive, and the Micro:bit will reset, and the program is active.

You can remove the Micro:bit from the computer at this point. The program will start running, and without the rest of the circuit, it will not function.

A little bit about the code:

The main feature of the program spirals the image down to nothing. It does this by drawing a bright LED, and a “black” LED behind it. A black LED is just turned off if you are wondering.

Then the code flashes a square three times when the spiral finishes.



The schematic is the simplest I could make for a first version. Wire it up like the drawing.



Place the soap on the button!




When you turn the system on, it’ll start up immediately.

However, it’ll be set at 1 second. It’ll take 1 second to wipe the screen.

Press button “B” to increase the time by one second. You could set it for 20 seconds, the recommended hand wash time fighting the virus. Or 25 seconds to adjust for the time it takes to start washing, I suppose.


To reset the time, just turn it off and on.


Step 5

If you’d like to change the image without counting down, just shake the Micro:bit. The accelerometer triggers an image change.



Fight the virus, don’t skimp on the hand washing. This just might help curb the tedium.