3 minute timed brushing timer

All my life I'm afraid of dentists. I go to treat my teeth almost every year. After the next questions: “Do you know how to brush your teeth? Do you brush your teeth for 2-3 minutes? ”, The idea was born to create a device that would monitor the time of brushing. The idea got stronger and turned into a timer for 3 minutes. The first prototype was bulky (7x3x3 cm) made of glued plastic sheets (there is no photo because it was lost), it was powered by a large battery, but it performed its function. But I wanted something less, in terms of size ... The idea lived with me for several years, I got a simple 3D printer and finally decided ... And let it still glow in the dark!



Objectives:

• compact device with one button;
• loud clear signal;
• powered by a small battery (“tablet”);
• print the case on the printer.

Tasks:

• 3 minutes after pressing the button, play the melody;
• nothing more.

Usage Algorithm



After pressing the button, the “start” melody sounds. I'm starting to brush my teeth. Further, at the end of the first and second minutes, a “beep” sounds to roughly orientate in time. After the third minute the melody “finish” is played (in my case, an excerpt from a Russian folk song “two funny geese lived at the granny”).



Board manufacture



Attiny13A controller. Small, quite economical in terms of nutrition and I have a small supply of them.



A piezodynamic was taken as an acoustic system. He was lying in a box for a long time, so I do not know his name. There are two main options for connecting these speakers to the microcontroller:

• one contact can be planted on the ground, and the second can be controlled via a microcontroller
• connect both contacts to the microcontroller and apply different logical levels to them.

I chose the second option, because it is louder, and I have many free legs (3 out of 5).

I wanted to make an LED display, but I realized that it was superfluous. Sound is more than enough.

I chose the CR2032 battery as power.



The board is very simple and compact.







There is a lot of free space left on it. Descendants will be able to place a temperature sensor and teach the controller to communicate useful information and motivating slogans through the speaker. I do not need this, and there is no free space left in the controller.



Body



The case was printed on a 3D printer from a luminous PLA. Nozzle 0.8 mm, large parts print very quickly with acceptable quality for me.







It consists of a glass with a button cut out at the bottom. The lid springs are cut out.







To form the springs, you need to heat the lid, then the plastic softens and can be molded like clay.



Assembly diagram







I thought and invented a system for pressing a button for a long time. So far, knowledgeable people have not shown this simple method without additional details. I repeated it as I could.



When you press the case, the upper part bends and presses on the speaker. The speaker presses the button and the timer starts to work. Pretty simple.



Sound example



In order not to remove 3 minutes, I wake up the controller by pressing the button.





Output



It turned out to make a primitive device with one function without any settings. Long cherished the idea and therefore this device fully meets my needs! Of course, the case would be even smaller and ergonomic. But the first printouts completely satisfied me. While I use this option and it suits me. Brushing your teeth has become more interesting, and most importantly now the problem is not to withstand 3 minutes of brushing, but to keep within them. The battery lasts 4 months. And the glow function was not useful.



Link to GitHub (I doubt it very much, but all of a sudden someone will want "the same").