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.
Version 3 of the hand wash timer. This time with sound!
Lights… yeah… that’s one way to show a timer (See V2 in this link). But, the tedium of hand washing has now prompted me to turn to sound.
The Micro:bit has some basic speech synthesis built-in, perfect for this situation. So, my goal this time was to have the Mico:bit count down the 20 seconds, or whatever amount.
For nostalgia's sake, the results turned out like those old text to speech sound-card programs from the DOS days.
How the system works:
Once again, when powered, the Micro:bit waits for the user input.
Pressing the “A” button will increase the time it counts down. So, when A is pressed you will hear an audible number.
Again, I don’t have a very sensitive button for this project. 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 almost nonexistent. However, my salvaged button travels about 2.54 cm (an inch). I give it a gusto press, and the sequence starts.
I added another function, a cancel button. Pressing “B” on the Micro:bit itself will cancel the sequence. Stops the countdown, in other words.
Only issue I had was the sound level from direct connection to the speaker. I know this could be remedied with using a powered speaker or amplifier. But, that’s an issue for a future version, I’m sure.
First, let’s gather all the necessary components you’ll need to build this project.
1x Kitronik Inventor’s Kit (This is mainly for the breakout adapter and project wires.)
Project Wires Female - Male
1x Speaker
Video demonstration of the project:
STEP 1
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.
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A little bit about the code:
Yes, the countdown time only goes up to 30. However, do we need to wash hands for longer than that? 
STEP 2
The schematic is the simplest I could make for a first version. Wire it up like the drawing.
STEP 3
Place the soap on the button!
STEP 4
When you turn the system on, it’ll start up immediately.
Press “A” to increase the time to whatever you want. I set it for 5 seconds to start.
Dispense soap, and the sequence will start.
Step 5 optional
Press “B” to stop the sequence at any time.
Conclusion:
Super-computer voice to the rescue!
Top Comments
I'm sure it could be done on Arduino.
However, the Microbit is pretty useful device.