Stepper Motors -- a back story to my scraper-sharpener project.

While working on my "low speed motor" side of the project, I encountered a problem.  When I turned the power supply on, often as not the stepper wouldn't spin -- it would just buzz loudly.  This happened for several different steppers, including a new one.  So what was going on?

I did figure out that I could get the stepper to turn by giving the diamond disk a good spin with my hand, but wasn't sure why until I read an article written by some college students who designed and built their own stepper motor controller.  The controller included speed and acceleration control.  They mentioned that a stepper has limitations with regard to acceleration.  If requested to accelerate too quickly, the stepper can't follow so it will lose steps.

I think my simple oscillator circuit is the culprit.  It immediately starts oscillating, so the stepper is requested to basically instantaneously accelerate.  That's not going to happen so it exhibits the ultimate in lost steps -- it loses them ALL and just turns into a noisemaker.

To solve this I am working on a modification to my 555 oscillator that will produce a ramped output frequency.  My first attempt using a capacitor on the control pin didn't pan out so back to the drawing board.

I suppose I could replace my oscillator with a microcontroller but that just seems like overkill.  But then I could claim I have the beginnings of a CNC sharpening setup <g>.