rotary encoder/pulse generator

I am in need of a way to convert the rotation of a shaft (manually rotated) into pulses.

The situation: I have a Parker stepper motor controller/driver/motor combination that I am using to help my brother develop some mechanisms. I noticed on one of his CNC tools that he can rapidly move an axis by rotating a large knob. I am guessing that this large knob is attached to an encoder of some type that send a pulse for each increment. The controller I have will accept pulse input (about 3.5 volts) to increment the motor so all I need to do is come up with the device to generate the pulses.

I can easily find the slotted opt0-interrupter components in Jameco and other catalogs - I just need what I imagine is the rest - I imagine a small slotted wheel - or plastic with dark/light sections to create the interruptions. No need for precision - the point is to generate what might be 20, 50 or more pulses per revolution so we can move the motor manually.

I have to admit that I am having a lot of fun with this.

What is this called and where can I find a source of reasonable low cost devices? It's probably right in front of me and so very simple.

Thanks.

I think you will find that the "big knob" is hooked to a potentiometer that controls the speed of a pulse generator. The faster the pulses the faster the travel.

You need to make a 555 astable pulse generator. Wire the output of it to your driver pulse input. Google " 555 astable " for circuits.

The knob on the machine I described is turned by hand but will rotate an infinite number of times in one direction. In this case the knob has a scale marked on it with each increment corresponding to some distance - possibly 0.001".

I did consider what you are suggesting though, a pulse generator that can run from slow to fast - and I may end up at that if I can't find what I need for a modest price. An alternative for me would be to purchase the opto-interrupter and make a shaft/wheel. I did find something close to what I've described at a robotics site. The problem was that particular product required interfacing with a micro-controller.

Thanks for the suggestion

Here are a couple of contacting incremental rotary encoders from Jameco. They have quadrature outputs that you can derive direction from. You have to add contact debouncers, but they are relatively simple. See this page to get price and availability info.
I haven't used these parts.

https://www.electro-tech-online.com/custompdfs/2009/12/776386.pdf
https://www.electro-tech-online.com/custompdfs/2009/12/1983635.pdf