I got started on this project because I added my two-pennies-worth to the comments on alpacaman's wooden clock about using mains-frequency timing to time a clock. To my mind it is not worth the effort of using an AC transformer and adding a rectifier, filter and squaring circuit when for about the same price and effort you can use a watch crystal. In addition to using a wristwatch directly, as in my comment , I have five times made my own oscillator. Two used Dallas ICs,one a Ds1302, and the other a Ds1307. Three used CD4060s, which provide a 4-Hz signal. Both can be trimmed to exact frequency, and will run for years on a coin cell. Plus, the Dallas ICs provide the date and some memory to boot.
After making that comment, I thought I would do it again with a watch, using a better interface circuit. By using an op-amp to provide the watch's pulse current, no dropping resistor needs be used. It turned out to be more trouble than using a crystal oscillator, but having made it, I wanted to use it. About this time after reading up on servos, I felt that I preferred stepping motors, especially for a clock. It helps that I have no servos, but I do have several stepping motors, recycled from 5 1/4" floppy disk drives.
Not wanting to compete with alpacaman's beautiful handiwork, I used a dial from an old Las Vegas souvenir clock, whose movement had 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.
For full details see: http://projects.worsleyassociates.com/Stepping_Motor_Clock/index.html?
Note: I have now posted my code in downloadable form in:
http://projects.worsleyassociates.com/Archive/index.html
After making that comment, I thought I would do it again with a watch, using a better interface circuit. By using an op-amp to provide the watch's pulse current, no dropping resistor needs be used. It turned out to be more trouble than using a crystal oscillator, but having made it, I wanted to use it. About this time after reading up on servos, I felt that I preferred stepping motors, especially for a clock. It helps that I have no servos, but I do have several stepping motors, recycled from 5 1/4" floppy disk drives.
Not wanting to compete with alpacaman's beautiful handiwork, I used a dial from an old Las Vegas souvenir clock, whose movement had 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.
For full details see: http://projects.worsleyassociates.com/Stepping_Motor_Clock/index.html?
Note: I have now posted my code in downloadable form in:
http://projects.worsleyassociates.com/Archive/index.html