Epilogue ?
With even more help and assistance from
David G4EBT I managed to solder up the PCB he supplied with all the required components, fitted a switch and an LED while managing to squeeze everything, along with a PP3 battery, into an ABS box measuring 4 inches x 2ΒΌ inches x 1 inch - a really tight fit!
All that shows is a switch and an LED - is that it I hear you say!!!!!!!
Various tests with a strobe disk had been carried out throughout the life of this project starting at the Breadboard stage and working through all the different versions so I thought I would Post something on YouTube just to prove that it does indeed work. The strobe disk that I have is a hand made job printed on paper from a template from the Vinyl Engine Forum and just stuck to a piece of cardboard meantime. Must devise something more elegant for this - any suggestions warmly welcomed!
So here is Test 1 showing the 300Hz strobe measuring the turntable speed at 33⅓ RPM - hopefully you will see the strobe bars on the outer ring remain stationary: -
https://youtu.be/wI7spkQzXO4
And here is Test 2 showing the 300Hz strobe measuring the turntable speed at 45 RPM - hopefully you will see the strobe bars on the inner ring remain stationary: -
https://youtu.be/Xl2VTXeNxZ8
Apologies for the shaky camera work!
It's been a long and often arduous journey to get here but a lot of time was taken to understand and control the duty cycle of the asymmetric square wave which has helped to improve the sharpness of the strobe bars pattern. This was achieved but at the cost of some light output and the transistor stage added towards the end really helped ameliorate that.
I've added a Post (#1090) to "The Thanks Thread" - credit where it's due.
https://www.vintage-radio.net/forum/...16#post1151816