My problem is to rotate a planisphere (a star chart) at the sidereal rate.
I will set the planisphere to its initial position manually, then turn on some device which rotates the planisphere on its central axis, to keep it in sync with the current sky at my location. That is, the problem is to rotate a circular, laminated bristol-board (heavy paper) disc once every 23 hours, 56 minutes. The laminated disc may be from 10 cm across to 60cm across, and is fairly lightweight. The disc may be horizontal, or vertical (hung on a wall).
A small, lightweight mechanism is preferred.
Battery power is preferred.
High accuracy isn't needed.
The disc would be rotated\updated once every 10 minutes or so.
I'm thinking that the mechanism would likely be placed at the edge of the disc, not the centre, and a little wheel would be firmly pressed against one face of the disc. When the little wheel spins a full rotation, it turns the disc by perhaps a few degrees.
I prefer simpler mechanisms over complex ones.
Can you provide suggestions for implementing this?
Here is a photo: