This is a very crude X-sweep sawtooth oscillator made of 884 thyratron tube and adjustable RC network. R is 300K + 2M potentiometer, C is selected with a rotary switch.

So, 2M resistor adjusts X-sweep rate within selected timing capacitor range.

Yes, I did notice that the aluminum windings on the one I disassembled looked pretty thick. I don't think iot did much though because the top of the light fixture when running for a while was still too hot to touch.

So essentially both ballasts run lamps at similar power, but since the commercial version is CWA (more constant-current than HX) it will overdrive energy saving lamps. Very cool.

The commercial ballasts generally have copper/thicker aluminum windings so they don't heat up as much.
Most of them are high power factor, because commercial/industrial customers get billed for power factor as well.

The reason a F25T12 cannot be run on a commercial ballast has something to do with the capacitor. It is the same reason
you should not run an F34T12 on a commercial ballast. It will make it overheat (or at least run hotter). If you run
an F25T12 on a commercial ballast it will also run at full 40W power.

Here's a discussion about the F25T12 lamps: https://www.lighting-gallery.net/gallery/displayimage.php?album=7829&pos=14&pid=253074

Posted this on Reddit, thought I would put it here too cause why not.
https://www.reddit.com/r/AskElectronics/comments/1pzrlwb/vacuum_tube_oscilloscope_project_what_does_this/
Anyone have good knowledge on vacuum tube scopes? There is a 2 meg pot on the plate of the 884 that I don't really understand.

We have a real tree, but only decided to go this route after 15+ years of service from the Sears Trim-A-Tree had nearly all of its light garlands die, and unfortunately the light sets used unique/hard-to-find bases, so replacements were costly.

This is the third year of cutting an ~8ft live tree, and the whole family loves it, including the furry feline. (Him especially  )

The page (and I assume eyelighting) is down/removed. Anyone have an archive link?

I made a post here comparing some of the physical and electrical differences of residential and commercial fluorescent ballasts:
https://www.lighting-gallery.net/gallery/displayimage.php?pos=-264949

What other differences are there? The residential ballast says nothing about thermal protection on it so I am thinking that might not be present there. I hear that 48" F25T12s can only be run on residential ballasts, is that because they normally underrun F40T12 lamps?

No recent pics of those ballasts yet, as I've simply been in and out of that garage with the Genesis, but I will be taking pics of all five of those GE Bonus
Line ballasts in their current state, soon. I do have pics of those ballasts in the past though, somewhere in my gallery.
4 of them are 0.32 amp cold temp Trigger Start, and one of them is a regular 0.28 Trigger Start. All of them lit both T8 and T12 lamps very bright...
they are some of my best ballasts in my collection... so if I do test them and the tests all pass, I'll definitely find a use for all of them at some point.
The other 10 that have never been used, are all Valmont Bonus Line 0.28 amp Trigger Start ballasts.

Here is how I like to think about it. You have two options in my mind:

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1):
Keep them because they are rare, and never put them to use.

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2):
Use them because they are useful. If they end up failing, it doesn't really matter because you can still keep them for their rarity. If you were gonna keep them boxed up because they are rare, then it doesn't matter if they are working or not because they aren't being used.

Now of course if they do fail while in use, there is a possibility that it will leave the ballasts visually disfigured, which will make them not-so-ideal for keeping around as rarities. But if they are thermally protected you should be fine. Maybe put a fuse in line to protect them if you feel the need, fuses and fuseholders are very cheap.

---

I know my stance is probably a little more utilitarian than other users here, but to me it makes sense. Obviously I am a stranger and you don't have to listen to me, but the stakes here are low in my opinion.

Not to mention that these ballasts are almost always potted in tar, and "a slight bit of rust development" is almost certainly nothing to worry about in the first place. Even if it was completely covered in rust, I would still try it out (with proper safety precautions of course). Do you have a picture of the rustiest one of them all?

@Multisubject, this is what I'm thinking as well. There's a small additional lighting project that I'm thinking about doing with LED light tables,
that would involve two of my rare cold temp HPF magnetic Trigger Start ballasts for smaller T12 or T8 lamps. Unfortunately though, one of those ballasts
has a slight bit of rust development. I plan on bringing in all five of those GE Bonus Line ballasts to see if they all work, but I know that negative
results can prove to be catastrophic.