wind up timer device
can someone help me find out a way to make a wind up timer? - all it needs to do is manually wind up by hand, unwind through a series of gears slowly.....but needs to have a strength of about 2kg/cm torque. something to unwind for about 30 minutes would be perfect
is there anything out there which can be used..or a simple way to make using spur gears and a coil spring?