OT: All Tube Color Organ

[threeneurons]

Not just being enamored with nixies, and dekatrons, but tubes in general. At least they're gas filled thyratrons. Not a display tube, but they can control some pretty bright light emitters (light bulbs), in the form of a color organ. Of course, I'm not the first to do this. There's a project article, on it from 1959:

https://threeneurons.files.wordpress.com/2017/11/radio-news_color-organ.pdf

But this circuit has some deficiencies, that possibly propagated into the solid state circuits, of the 60's and 70's:

The main problem, is that both thyratrons & thyristors (TRIACs & SCRs), are either ON or OFF. No linear section. That means brightness is adjusted by using some for of pulse width modulation (PWM). When using AC line voltage, the device [i]turn-ON[/i] is delayed (per cycle) relative to the desired brightness. Earlier in each cycle for brighter output. This is how your everyday household lamp dimmers work.

But for some reason, this never made it into color organ circuits. In those circuits, if the music is loud enough, it turns ON the light. If it ain't the light stays OFF. Pretty hap-hazard.

In recent years, I've made TRIAC versions of the color organ, that DO properly convert the audio level, to the corresponding phase angle, in each half AC cycle.

I've been wondering if proper control could have been done with tubes only. That means thyratrons. I've purchased several types, in the last few months. I've already had 2D21s and 2050s, in my stash, but bought beefer 6012s, 6014s (aka C1K), and 5559s for some serious current switching. I just finished a "proof of concept" circuit, and here's the results:

Basic concept:

My thyratron page:

https://threeneurons.wordpress.com/miscellaneous-projects/thyratrons/

And a video of the working circuit:

https://youtu.be/z7YYyiGx9Gg

Enjoy.