2:1 or 3:1 slip gear

I would like to rotate a prism so that the rainbow can be moved to different locations on a wall. I want it to be driven by a standard servo that rotates through a 90 degree arc. But I want the prism to only rotate through 45 degrees or 30 degrees. So that means using something like a 2:1 or 3:1 gear.

I also want to be able to manually adjust where the rainbow is as well, so I want the connection to “slip”

What mechanisms would you suggest?

Hi there,

Welcome on the forum.

I’m not sure what your project is, it is hard to figure out without a drawing or a schematic.
Please, feel free to join a drawing of your idea and it will be my pleasure to help you with the project.

If you want to rotate something to a precise angle and position, a servo motor would fairly do the job pretty easily.

If you want a continuous rotation, a small DC geared motor would do the job.
Note that you would probably need a slip ring for your connection: https://www.robotshop.com/en/catalogsearch/result/?q=slip+ring&order=relevance&dir=desc

Give more information on your project and I will be able to help you further.
Cheers!