Process

1. Wiring up Timer. The timer in this circuit is a Servo.

2-a. Wiring up Solenoid. The first intention was to make a solenoid sound to indicate a few seconds left until the time was over. However, the solenoid didn't work properly.

2-b. As an alternative, I used Neopixel to gradually glow up when there are less than 1/3 times left compared to the user's input time.

3. Make a switch that starts the whole process. After the user types in the desired time through the console and toggles the switch, the solenoid Time Timer will begin.