According to the ADA, we are supposed to brush our teeth for two minutes for optimal results. This works out to 30 seconds per side of your top and bottom teeth. I used to use a powered toothbrush that had a built-in timer and it would pause ever so briefly when it was time to switch. It was a great feature, but I had one break and after replacing it eventually decided the cost of the replacement heads were too much (not to mention the toothbrush itself).
I wanted a less expensive option. So I looked for a way to build a simple timer that provided both audio and visual cues when it was time to switch the side of your teeth to brush. The audio cue needs to be audible over the sound of running water or a running hair dryer (spouse/roommate compatible). In the event the sound is not audible (the hairdryer is a tough one to overcome) the visual cue needs to be obvious.
Here is what I came up with:
countdown starts at 3 seconds, beeps after first 30 second interval at 33 seconds
This repeats until the two minutes are up, using one LED per 15 seconds. I only use 8 of the 10 LEDs so the time period can be evenly applied as an integer to each LED.
Parts List
Code
That’s all there is to it. I’m sure the code can be written to work with the newer generation Circuit Playground as well.