Pictured below is a timer we recently designed and built to act as an accurate timebase for a Lazy Clock (see here for details: Lazy Clock – PDF plans for this wood gear clock driven by a solenoid)
The device we made has a real time clock module based around the Dallas DS1307 Real Time Clock (RTC) – top left of the board pictured above. This can be set up (via the Arduino Pro Mini at the bottom left of the board) to output a 1Hz square wave – i.e. outputting a high signal for exactly 0.5 seconds followed by a low signal for exactly 0.5 seconds, repeating.
The device can be programmed by the user to close the on board relay for 0.25, 0.50, or 0.75 seconds, every 1, 2, 3, 4, 5..etc seconds using this 1Hz square wave as a trigger. The relay switches the solenoid which in turn keeps the Lazy Clock accurate to within a few seconds per day.
If you need any kind of relay timer, please email firstname.lastname@example.org with details of your exact requirements.