My OctoPi (Raspberry Pi Cam) has purple hiccups

 

That, friends and neighbors, is what happens when my camera is working, but the R-pi is also plugged into my Ender 3V2... as it sorta tends to be if you want the one to control the other...

 Note the emphasis on 'my'.  Apparently other people are not having this problem.  Those that do, solve it by installing a ground / power isolater in the USB port, to prevent power supplies fighting or noise.  Sounds good, doesn't work.  This video was made with said device installed.  I also took one apart (I have several) and tried isolating the power ground not just the 5V line, same result.  Since I bought several, I've considered building little filter networks into one of them, but I don't think this is high frequency hash.  Bigger guns are required.

Just unplug the printer and the camera view becomes clean and noise free. Well that might be okay if all I wanted the R-pi to do was stream video of the print...but of course I want to control the printer with OctoPi/OctoPrint.

 My next instinct would to install some common mode noise rejection in the form of a whacking great ferrite, but said ferrite is MIA.  I need some really big Mix 75/77 clip-on ferrites.  Clipons seem hard to find in the low-frequency mixes.  Poop.

 Anybody got an old CRT sweep ferrite core mostly intact? That will work handily, just zip-tie the two halves together firmly and pass the cord through it two or three times.  Well I haven't seen one of those in fifty years. ;D

 This problem is annoying me because interference works both ways... I'd prefer not to throw glitches into the printer either.  So this has to get fixed before I will attempt to restart printing (mainly, profiling some filaments I haven't used before, starting a filament notebook or spreadsheet for filament settings, etc).  I have an old PowerBook with a bad battery which I keep on the printing bench for such utilitarian purposes, checking the camera stream, etc.

 I'm also sorta pondering how to make the R-pi camera video publically available without compromising my network.  In general, I do not poke holes in my firewall at all.  We'll see. That's a low priority.  In the past (before the upgrades, LOL) it was very useful to be able to check a print's progress remotely.  On one occasion while I was at work, I checked on, and stopped a print which had come loose from the bed and was doing the Bird's Nest Dance.  (solution: Layerneer Bed Weld, man, we lurves it)