The Macetech Chronodot is an open source clock module that fits into the socket in our Bulbdial Clock kit. It's based around the Dallas DS3231S real time clock (RTC). That's a hybrid chip incorporating a temperature-compensated crystal oscillator (TCXO), and is specified to provide accuracy within +/-2 minutes per year, if kept between 0 and 70 degrees C. The Chronodot (V1) module comes almost ready to use, with the DS3231S pre-soldered on the board. You get to solder the headers and (included) lithium battery when you're ready. Battery life is estimated to exceed seven years when used properly, and the battery is replaceable. Additional documentation is available at macetech.com. The Chronodot has been released as an open source design as of September 2010.
