Dual Timer for Bathroom with Sound and Light!!

Every time we need to wash our hands or brush our teeth we had to estimate for how long we should be doing it.

Therefore, we decide to build a very simple dual timer, with two buttons:

• one lasting 20 seconds, to wash the hands properly;
• one lasting 2 minutes to brush the teeth.

Circuit implementation:

The device is based on the microcontroller tiny85. Since it has a very low energy needs, but it is powerful enough.

An overview of the electric diagram is shown below.

The power is provide by an USB power Bank as shown in the picture below.

Two buttons, one for hands and one for teeth, are attached to the microcontroller ports P2 and P3.

While the timer is counting a led attached to port P0 is switched on. Then, while the timer is on a buzzer beeps every second for the 20 second timer, and every 6 seconds for the 2 minutes timer. The buzzer is activated by a transistor 2n2222 which base is connected to the port P1 of the microcontroller.

Finally, we added two switches, one for the main power, the other one for the sound... to avoid any sounds going off during the night...

Attached below the code to activate the timer.