I am a software engineer with no knowledge of mechanical engineering. I need to buy or build a rotating disc which can rotate in 30 degree steps only i.e each time I try to rotate it, it should take a 30 degree step and stay fixed in that place. Hope it makes sense.
Searching on Google I could find only info about electrical rotary encoders. Unable to figure out how to search for mechanical devices I need.
My guess is these sort of devices must already exists. Can please share any info you may have on this and provide suggestions on buying or building this.
Update: As shown in above pic, on the surface of the disc, there would be LEDs of different color, spaced about 30 degrees apart (or 45 degrees). Each time I want to point one specific light to the sensor. So from time to time, I want to manually rotate the disc to make the required led point towards the sensor (i.e some led pointed exactly to sensor and no intermediate position) and be it locked there.