Dry and Mighty Toothbrush Smart Cup - was created to address a worldwide problem - wet slimy toothbrush cups.  No one wants a slimy toothbrush cup with icky water inside. Looking around the Internet, I found no good solution except to make one on my own.

I designed the Dry and Mighty Toothbrush Smart Cup using space age technology (3D printing, Ardunio and software) to rid the world of wet toothbrush cups one bathroom at a time.  I use mine every day.

Dry and Mighty uses a simple accelerometer to control a fan to dry your toothbrush so it is less likely to ever build up a pool of muck in the cup.  

All parts are 3D printed WITHOUT any support.  You might get a slightly nicer print if you use support but I did not use any and it came out really good.  

November 5, 2019.  Uploaded a V3 of the cup itself with smaller "windows" to prevent the base of the toothbrush from sneaking out.

The principle design of Dry and Mighty are 1) Use as much of the stuff you have in your house already,  2) an accelerometer, 3) Ardunio Micro, and 4) Generic USB power supply (which you have many laying around the house.)

An accelerometer (MCU6050 module) is used to sense motion/vibrations in the cup (e.g. removal or replacement of a toothbrush, razor, etc..).  Using an Arduino Micro as a controller as the main brain, tied to the accelerometer - Dry and Mighty turns on the fan to dry your teeth cleaning or shaving device when it senses movement.

To let the user know the Dry and Mighty is active an optional LED is used as an indicator for the drying.   

Dry and Mighty uses a small muffin fan (Easycargo pi fan model EDL3007S05) which is quiet and able to blow air onto your wet teeth or other body cleaning devices.  The fan is a 5V fan which draws 0.12A. 

A small fan controller is made out of some spare parts (Optionally, a solenoid could be used if you don’t want to make your own fan controller).   

MOSFET(Vishay Si2318DS) is used to buffer the Arduino I/O pin. A flyback diode is used to protect the MOSFET from the inductive load of the fan.  I used a 1N4148 that could meet the specs for the load.

The fan acts as an inductive load, so when the MOSFET is switched, the current cannot change instantly.   The diode should be rated with at least the same current rating of the fan.  Since the fan will not be switched on/off quickly, power dissipation should not be a problem.

I used basic MPU6050 reference code to read the accelerometer data. 

The software computes the change of the accelerometer.   The square of the change of accelerometer is used as the threshold to turn on the fan. This 

threshold value is in the file toothbrush.h, ACCEL_SQR_ERR_THRESHOLD.

The fan on time in seconds is also in toothbrush.h, FAN_ON_TIME

You may “Tune” the software to suit your personal toothbrush drying needs. ;)  Sample code - when permissible is 30 minutes and it resets to 30 min if there's additional movement.

Myminifactory for some reason doesn't allow me to share the sample reference code.  Maybe after the design competition they will allow it.