Back then...this is what we did...

[lasermaster1977]

I've been putzing around on and off from one project and thoughts on numerous others over these many months, never getting much of anything done except lots of CAD drawings of components and ideas. Its been harder to stay focused on any one thing, sorry to say.

But, good things (hopefully) come to those who wait.

One contemplative putzoid thought of mine over these past years was derived from looking and learning from those who've implemented lumia effects either in dedicated lumia projectors or stepper driven mulit-lumia/diffraction grating wheels, and comparing these to those we built into my first RYGB scanner/lumia/diffraction grating projector. They were made of easily available components, cheap to acquire and simple to build. They weren't fancy but they worked well. Effect wheels were moved into and out of beam paths manually, by pulling on strings running through tiny Teflon pulleys...truly.

Page 6, post #42 showed how a recent recreation of what I used back then... several (6) Synchron 110VAC slow speed motors (.5, 1 and 2rpm variants) to rotate either diffraction gratings via rim drive or lumia wheels mounted directly on the motor shafts. Back in the late 70's, Edmund Scientific sold these Synchron motors for $1 apiece. They were heavy and bulky, rock steady smooth. Back then I wished there had been a variable speed solution to these Synchron motors, no doubt there were but they didn't reveal themselves to me in a viable way.

I got gobs of "stuff" that I've acquired over recent years but never the time, or more succinctly the inclination to tinker.

Then recently, I saw on-line a miniature stepper driven lead-screw I wished I'd had the wherewithal and know how to use back in the day. We originally used some cheap-o lead-screws that were driven by DC motors with plastic gear reductions but they were growlingly loud.

This pulled into focus all the related ideas I've contemplated and considered for my "new" lumia and diffraction grating effects and whether to use them with the RGB scanner output beam(s) or with a separate, dedicated RGB LED outputs.

I used relatively big NEMA 23 hybrid stepper motors and H-bridge full and micro-stepping drivers on my DIY CNC machines going back to 2010. Only recently have I discovered how small some steppers have become.

Tonight I just tested using the 28PYJ-48 unipolar stepper with the ULN2003NAPC stepper driver as a "effects wheel motor and was blown away by how well it worked and how smooth it was. I did a quick (and easy) substitution of it on the rim drive mount in the page 6, post #42 and here are two photos of the result. (coming soon with a YT video link)

28PYJ Stepper Substituted, Rear and Side Views


On the rear view I've sketched out lines that show reduction of mount size, plus the mount could be made of thinner acrylic material in not thin aluminum.

The 28PYJ is a 32 steps-per-rev stepper driving a 64:1 geared output shaft yielding ~2048 steps per rotation and runs nicely off of 5VDC, plus it is dirt cheap, super small, and easily modified to a bipolar stepper and driven with the better DRV8825 and/or DRV8833 chips.