| This clock is timed with a watch, using an op-amp to provide the watch's pulse current, thus no dropping resistor needs be used.The two stepping motors are recycled from 5 1/4” floppy disk drives. This is not a fancy-looking project: it uses a dial from an old Las Vegas souvenir clock, whose movement has expired. However, since the apparatus is self-contained, it can be put behind the dial of any large clock. I selected two 200 steps/rev motors, but had a problem hooking them up to the coaxial hour and minute shafts. Fortunately, I have a brass bevel gear set from a ham radio condenser drive, so the hour motor could be put underneath. To couple the motors to the shafts, I used short lengths of fuel hose. The shafts are from an old dual potentiometer. The Picaxe is an 18X, to drive the eight coils via a ULN2804. It, and the watch circuit, are powered from a 3.6V cordless-phone battery, so they are independent of the line-powered motors, which use a 12 volt “wall-wart”. If the power fails, the Picaxe counts the lost seconds, and advances the hands after power is restored. It also corrects the timing of the watch, which runs fast. |
| Here are photographs |
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Here are the circuit diagrams |
| Here is the code |