Obsolete fluorescent light fittings

[broadgage]

As posted above, some vintage fluorescent light fittings use a filament lamp in series with the tube, these are no longer readily available.
The exact voltage of lamp required would be appreciably less than 230/240 volt mains, and appreciably more than the readily available 110/120 volt lamps.

I believe that I may have located a source of 196 volt, 60 watt GLS lamps, these might be more suitable than the 230/240 lamps that some members have tried.
I do not know if these are NOS, "when its gone, its gone" or if they are still manufactured for some odd application.

[Refugee]

I once looked in a book at tech college library and found a circuit in it for a British Rail Ballast that drove a 5 foot tube that ran from 24V. It used something like two OC35 transistors and relied on the "overshoot" spikes to strike the tube. It was just a multi-vibrator with a center tapped transformer. I have no idea what frequency it ran at though.

[Ed_Dinning]

Hi Plenty of designs for these about, after germanium types Silicon planers (low Vce) were popular, now it would be FETs. Typically operated at 20 to 35Khz, where luminious efficiency increases over that at 50Hz and is also not audible.
I've built many of these for camping lights operating off a car battery in years gone by.

Ed

[bobbyball]

I picked up a rather nice twin (32 + 40 Watt) circular fitting a while ago for my lounge as I wanted a very bright light for when fiddling with the hi fi but it buzzed annoyingly having two large chokes. As an experiment I picked up a "high frequency" ballast unit designed to work two lamps of approximately the same wattages (although the modern "thinner" types) and it works a treat. Completely silent, lamps both strike virtually straight away and together, and seems marginally brighter. Good "marriage" of "retro" fitting with "modern" innards. I also have a few of those Japanese desk lamps (one particularly nice one made by "National") with perspex shades but again they were buzzing annoyingly. They don't use a starter: the mains switch has momentary break contacts that you hold down briefly and let go which mimics the action of the starter and strikes the 15 watt tube - if it isn't too cold that is. Found a really small HF ballast unit that fits where the old choke went and now instant, silent light!!

Robert

[Herald1360]

From what I remember as a youngster, early inverter driven fluorescents in public transport tended to run in that painfully annoying frequency range between about 10kHz and too high to hear.

[bobbyball]

I think you might be right there Chris, remember the London Underground trains from the '60's ("C" stock perhaps) that had a very obvious "whine" in the carriages...

Robert

[Tazman1966]

And so did the MCW Metrobuses that had all the inverters for the saloon lighting for both decks in a cupboard at the top of the stairs. There'd be a veritable cacophony of whistles and whines if some of the tubes were spent. They still managed to light to an extent though which meant that they didn't get replaced straight away. They were wired in pairs with one inverter driving two 20W T12 tubes. The original colour was Warm White but as they were replaced, eventually scant regard was paid and all manner of colours from "White", "Natural", "Cool White" and "Daylight" fitted. There was also a blue one fitted above the first seat by the entrance doors.

[Framer Dave]

Originally Posted by Tazman1966

There was also a blue one fitted above the first seat by the entrance doors.

At the risk of taking the thread OT, can I please ask what the blue one was for? I've always wondered. Someone once told me it created ozone to improve the quality of the atmosphere aboard the buses Over to you, Tas.

Kind regards,

[Herald1360]

Wasn't it less likely to upset the driver's night vision?

They also seemed to make book pages fluoresce a bit (presumably higher UV content), so even though the light was dim, you could still read by it!

[broadgage]

Originally Posted by Framer Dave

At the risk of taking the thread OT, can I please ask what the blue one was for?

It was said that the blue light was less likely to distract the driver at night.
I dont believe that blue was significant in itself, but the blue lamps tended to be much dimmer.
Some modern buses use LED lighting, the lights near the driver are blue, but being LED they are as bright as the white ones used elswhere in the vehicle and seem a bit pointless.

[Nickthedentist]

I'd always assumed it was to allow the driver/conducter to spot forged notes and passes, or for stopping the dodgier passengers injecting drugs (this trick is widely used in public loos where there's perceived to be a problem). I really do learn something new here every day.

[michael cumming]

The toilets in Durham indoor market have those large UV tubes. I have a lamp with a blue tube in an it shows up white colours very bright, they put them in toilets to stop folk doing things they should not in there, that said the ones in Durham don't seem to work that well as there is too much daylight in there anyway so what is the point?

[Tazman1966]

Originally Posted by Framer Dave

At the risk of taking the thread OT, can I please ask what the blue one was for?

Hi Dave

As others have said, it was less likely to cause reflections on the windscreen and disturb our vision

[michael cumming]

I don't have much in the way of Flourescent (fluorescent) lamps but love the retro look of them, the only ones I have are the battery ones but I have an old GEC starter.

[whyperion]

This thing buzzes at, I think, the mains of 50 Hz. New tube fitted yesterday, though the fault was the starter, which I have also replaced, leaving the choke or capacitor faulty or is that the design?

[Nickthedentist]

I would have thought that the choke would be the most likely cause of buzzing.

[Herald1360]

So would I.

You might be lucky and find it's just loosely mounted, but more likely it'll be loose laminations. Replace it or live with it- it's not likely to fail any time soon.

[whyperion]

Seems to have settled down now the new starter (and tube) is in place. Nothing noticable although the 50Hz rattle from the fridge-freezer now sounds louder in sympathy or replacement.

[yampy187]

I have the same thorn fitting in my parents shed. It makes a lot of noise when its cold. After a while it settles down.

[broadgage]

Re post 181.
I have now received these lamps, I was mistaken about the wattage, they are 100 watt, 196 volt.

Should run OK in series with a 4 foot 40 watt lamp.
The filament lamp would be somwhat underun, but less so than using a 240 volt lamp in series with a flourescent tube.