If you are a light sleeper and don’t need much to wake you up in the morning then this DIY Gentle Wake Up Alarm Clock by Michiel Spithoven might be the ticket for you. On the other hand if you can sleep through a thunderstorm then you may want to look into a real loud alarm clock instead. 🙂

“First I wrote some test code to check of a small microchip with internal crystal can manage to keep track of time. Well.., uuuuh.., the result was I lost three minutes a hour, not great.
Not having any crystals and it being Sunday I search for other ways of getting a decent timing signal. After some brainstorming I pulled a old alarm clock and search for a usable signal, I struck gold with a nice 1Hz signal.”