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Old 3rd May 2016, 5:39 am   #261
broadgage
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Default Re: Obsolete fluorescent light fittings

For modern 18/20 watt chokes, try looking for anyone that refurbishes offices.
Many offices are lit by modular fittings each 600mm square that drop into a false ceiling grid.
Look for fittings that use THREE lamps, these have a 36/40 watt choke for two lamps in series and an 18/20 watt choke for the third lamp.

The fittings for four lamps will contain a pair of 36/40 watt chokes.

The inductance of an 18/20 watt coke will be higher than that of a 36/40 watt choke, but not by a huge margin. The running current will be about the same, remembering that a 36/40 watt choke will correctly drive a series pair of 18/20 watt lamps. The voltage across the 18/20 choke will be greater due to the lower lamp voltage.

Fluorescent lamp chokes are not of course designed as smoothing chokes, but in practice work surprisingly well. They have the merit of being cheap if new and free if reclaimed.
The low price makes use of multiple chokes viable, in series for greater inductance, or parallel for higher currents. Chokes run in parallel should be the same make and type to ensure that the current is shared equally.
The low price of the components makes multi stage filter circuits very affordable for high quality audio.
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Old 14th May 2016, 4:16 pm   #262
rosie&jim
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Default Re: Obsolete fluorescent light fittings

Just retired from a lighting company (small private) and I can say for sure that we still had 5ft bayonet warm white and daylight tubes, and also bi pin to bayonet adapters in the warehouse!
The boss wouldn't let us dump them as he always said "their on the stock sheets".
I'd say that at least 10 yrs ago small series twin tube single choke fittings where still being produced. It's worth noting that all series fittings MUST be fitted with "series" starters or only one tube will light reliably.
I seem to remember that some twin 6ft 70w fittings had 1x75w choke and 1x65w fitted as standard.

Dave.H
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Old 15th May 2016, 9:47 pm   #263
1100 man
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Default Re: Obsolete fluorescent light fittings

Hi everybody,
Have recently rescued an Atlas 5' flourescent fitting complete with Mazda bayonet ended tube. I assume this dates from the early 1960's but can't be sure- I was hoping there would be a date on the capacitor but there isn't.
Its built like a battleship and weighs a ton. I rebuilt the fat starter with a modern one and it all works fine. I do like the tapped ballast for different voltages- never seen that before.
Hope you enjoy the pictures!
I also rescued a couple of T12 'Power Twist' 5' tubes. These are marked 'True-Lite, Duro- Test, 65W preheat. I believe they are used for growing plants but does anyone know anything about them? Have never come across them before.
Cheers
Nick
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Old 16th May 2016, 10:54 am   #264
Brigham
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Default Re: Obsolete fluorescent light fittings

Splendid! It's in that mid-way condition where you can never decide what to do: keep it as-is, or refurbish it like new.
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Old 18th May 2016, 12:25 am   #265
Zelandeth
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Default Re: Obsolete fluorescent light fittings

Power-Twist tubes are one of the holy grails of lighting collectors over here! They were a rare sight in the US but never really gained any traction over here due to the cost. The ones you have are intended for daylight simulation and have a very high colour rendering index.

The reason for the twist is quite simple - an attempt to improve efficiency and get more light out.

The aim is to get more light out by positioning the phosphor on the tube wall closer to the core of the discharge in the tube - but without actually reducing the overall tube size too far. It's a balancing act as in terms of actual generation on the UV that excites the phosphor, a really wide tube to keep the current density low is favoured - but beyond a certain point self absorbtion of the UV by the gas fill starts to negate any gains - which is why the standard tube diameters were chosen, they were deemed to be the best compromises. Clever ideas like the Power-Twist line from Duro-Test and GE's Powergroove tubes were innovations to try to push things a bit further.

Take good care of them - they are some really rare bits of kit. I was lucky enough to come across a couple of 2' 20W Power Twist tubes (at no small expense!) a few years back and consider them to be some of my most prized items in the collection.

The BC capped Mazda tube is of course a rare beauty as well, just probably not as rare as the Power-Twist ones...

It should have a two letter date code somewhere (such as DC) which I should be able to de code for you.
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Old 18th May 2016, 9:47 am   #266
1100 man
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Default Re: Obsolete fluorescent light fittings

ARRGH.. Managed to break one of the power twists I moved the box of tubes they were leaning against and never gave a thought to them. 10 mins later they fell over. Luckily one survived intact.
Many thanks for the information about them- very interesting. If the remaining power twist is of any use to you, you are very welcome to it- I am not really a collector, just interested when odd things come my way!!
I also rescued a box of new 40W T12 tubes if you need any. I never need 4' tubes for the old light fittings in the factories and workshops I work in, it just seemed a shame to not have them.
Cheers
Nick
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Old 18th May 2016, 6:46 pm   #267
hannahs radios
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Default Re: Obsolete fluorescent light fittings

Hi Zelandeth, are you a member of the lighting gallery? I'm on there as old lamps are a passion of mine.
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