ClockIt is a pretty simple microcontroller (ATMega168) based LED clock from SparkFun electronics. My partner and I put one of these together at Maker Faire a few weeks ago. It was a fun little project to solder together and only took about 15 minutes to build.
When we got it home I set it up in the kitchen next to Julia Child (an iMac). A few days later J was complaining that the clock buzzed quietly while running and that the buzzing changed pitch each second as the ‘:’ between the hours and minutes flashed on and off. I had also noticed when setting the time, the up and down buttons would alter the time by 5 or 10 minutes if you had previously held the button down to scroll the time faster.
Fortunately as SparkFun posted the source code for ClockIt on their website, I was able to tweak it to address both problems. I made a few small changes that keep the buzzing (noise picked up by the piezo speaker) at a constant pitch making it far less annoying. I also fixed the up/down button behavior while setting the time. The modified code is available here or on SparkFun’s forum.