Alarm Clock

Set a countdown timer to wake you up

The Story Behind the Project

I studied abroad in Zambia for a month, and I didn't want to bring my phone (which is my regular alarm clock), but I still needed a way to wake up at a certain time in the morning. The solution was obvious: build an alarm clock. I finished soldering it together the night before we left and programmed it on the plane (causing a flight attendant to ask with a concerned tone what I was doing). It all worked, and I used it almost every day for the five weeks I was in Zambia!

Features

• The Arduino's built in reset button works as a "snooze" button, since it initializes at 10 minutes and immediately begins counting down

• The digits are multiplexed, meaning only one is on at a time, each sequentially switching on and off at around 300 Hz. This cuts the number of display pins and resistors needed from 24 to 11

• The buzzer starts at a low volume and then steps up to a higher volume after some time

• The buzzer goes through a range of tones -- rapidly increasing and then decreasing in order to stand out against background nosie