Unusual low voltage ballast circuit

That is not a Royer oscillator, it is a Baxandall converter and works in an entirely different way. It is a resonant converter. See https://en.m.wikipedia.org/wiki/Royer_oscillator under Applications and sinewave variants

Jonas Otter

These look like the 3watt bulbs used on the portable Germ Guardian 1000 & 1100 series, plug in wall-mount UVC air filters. This would bode well with the "simple room air filter experiment..." V2.0...

Also, its the 184nm spectral line that creates the ozone.

Jeff Larson

With my study of UV in the last year I am seeing more spectrum charts showing that the UV of 184 nm from mercury vapor lamp of the quartz type is classified as VUV or Vacuum UV and UVc starting at 200 nm and continuing up to 280nm. The VUV being 10 to 200 nm. Very interesting stuff.

Jeff Larson

I can live with an analogue scope with a repetitive waveform. But DSOs come into their own when sniffing for transient events. The other thing I really really like with battery scopes is the isolation from Earth.

Mike Page

The trouble with this is, it's too interesting. If I had one I'd be flicking it on an off just to watch the strangeness and that eerie glow.

Wim

William, that was my rather toungue-in-cheek way of saying what not to do with this lamp. I guess it would erase an eprom, but there are better tools for that.

Normunds Gavars

They're there, but quite faint. I have to admit that while the modern digital scopes are very versatile, their layers of menus and options make the older cathode ray units look positively intuitive by comparison.

Big Clive

I haven't used eproms for years, but, Yes, I guess they'd erase them quiet nicely! How long does it take compaired to the ordenary fluoro tubes we used to use for that?

William Taylor

Solartron! That was the name!

Mike Page

Nice to see the scope, Clive. But I can't see the XY graticules. When I was barely a wee smudge my dad brought home a scope from work for me to muck about with. It was the size of a large suitcase, but on its side. Smelled like ... warm old kit smells! Absolutely unique. Anyway, as well as the brightness (beam) control it had a separate Graticule control - a few pilot bulbs I think. It also bit me more than once. I can't remember learning anything, but maybe that's not the point.

Mike Page

Also these lamps are very handy if you want to rejuvenate an old eprom chip. Makes them as good as new.

Normunds Gavars

I got one of these a couple of years back, Clive, when you first explored them. One seller had an AC 240v version which was a 4.7uf cap in series, and the 12v version, same as what you just showed. I also found an e14 version of the GTL3 but sadly it happend to not emit ozone! :( I recall at the time you were weary of the 240v dropper idea because of possible sputterring, but isn't this probably a 29khz version of the same thing? I'm not so convinced it would sputter with the cap, as the heater would keep the cap from being dumped too hard by conduction, and for most of the emissive coating area, there's also the resistance of the heater in series when the vapor does strike! Still, of course, at the time, I had to buy a few of these, as like you I think they are very cool! Oh, and the cap in paralell with the primary, Yes, I think it runs way nicer with that in, My hunch is they run resonant like you said, but if you remove the cap, they flipflop by core saturation, less efficient and les frequency stable!

William Taylor

CNLIGHT Snowlight UVC 254nm GTL2 GTL3 10V3W Nano UV Lamp eBay item number:183793081755 which seems to also suggest connection to mains with a Cap dropper.

Mr B Shepherd

I will say it over and over: I love these explorations! I learn something every time and it entertains! THANK YOU

Michael Thompson

There. I have yet again learned something new. This has to be the best channel on You tube for the simple, yet comprehensive description of how things work, even at my advancing years is easy to remember.

Mike Hughes

I found only one listing on ebay for a similar device, where did you get this Clive? - https://www.ebay.com/itm/3-7v5v12v-ultraviolet-UVC-cold-cathode-lamp-germicidal-lamp-drive-electronic-bal/184571096234

Willem Hengeveld

It's from eBay.

Big Clive

What did this thingy come out of?

Derek Smith