Author Topic: Ever wanted to see inside a Sylvania Flourescent Christmas l (Read 44260 times)

Chris W. Millinship · « **on:** August 12, 2001, 12:17:00 pm »

Well I did, and I had an opportunity to do so, recently. And since I`ve never seen anything else like it on the internet, I thought I`d post what I saw, here....

These are just too valuable to go cracking them open (unless they`re burnt out and in poor shape- none of mine are like that) so I wasn`t going to do that. I did, however, have one with a loose base. Today I found it again and decided to re-attach the base. To do this I needed to remove it, scrape out the loose cap paste and stick it back on. Epoxy works fine like this since I have no proper cap paste yet- and it doesn`t get that hot either.
So, carefully I removed it- which involved unsoldering and removing the brass cap, then softening a stubborn bit of paste that was preventing the otherwise loose bakelite bit coming right off, I used WD40 in the end- worked quite well. So off it came and here`s what I got....

Unfortunately, not knowing exactly what was in there before pulling it off, I broke the wirewound resistor`s core (probably a ceramic rod) but it was still intact electrically. Out of interest, it metered at about 1.3k ohms.

Interesting- I originally thought that the outer globe was just for show and inside, was a tubular neon-flourescent bulb. I was wrong. The bulbs are indeed genuinely globe shaped, phosphor coated types with a cylindrical metal electrode arrangement inside. This one is an orange (coral) one, but presumably all the other colours are made in a similar way. It remained to be seen, what the gas fill was.

Here`s the best macro shot I can get with my specially modified little camera, showing the electrode shape inside...

Two cylindrical electrodes, one on top of the other from what I can see.

So, to carefully power this thing and see what happens. 120 volts is applied, thankfully the damage to the wirewound resistor did not affect its performance. Fingers clear of those live crocodile clips and...

As can be seen, this one has a neon (well, probably something like 99.5% neon, 0.5% argon) fill. It wouldn`t surprise me if the white coating wasn`t a phosphor at all, but if it is, then it serves only to enhance the already bright neon-orange glow by flourescing from the slight amount of invisible-ish UV given off. Other colours probably have other gas fills like xenon, mercury and argon, coupled with different phosphors, much like the miniature green neon indicator-bulbs you occasionally see in some appliances.

To clarify, here is a diagram of what I imagine a cross section would look like. I`ve already spotted a mistake (the way the lead-in wire attaches to the top electrode) and it wouldn`t surprise me
if other details aren`t quite right. If anyone has a worthless, dead one they wouldn`t mind sacrificing to science, why not crack it open and snap a picture of what it actually looks like.

Feel free to add to, or correct my diagram. I havn`t ever broken one of these and don`t intend to (not working ones anyway), this is interpreted from what I saw looking through the gap between the bottom stem seal and the start of the white coating.

There you go then, just thought I`d post this for your interest. I`ll amend my description on my web site soon too and include these pics there.

Just one more pic though- just to prove I did put it back together and it still works...

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Chris W. Millinship · « **Reply #1 on:** August 12, 2001, 12:55:00 pm »

You`re not going to believe this.

Shortly after posting that lot up there (and it took ages, it kept hanging up after I hit "submit" and I was beginning to believe it wouldn`t work- thankfully it did eventually) I went off to give the bathroom another coat of paint cos we`re refurbishing it at the moment. I`d left the newly mended little bulb just on the shelf thingy sticking out of the bench, where my keyboard goes on as well. The window was open and it`s got a little windy outside here in dull grey South Wales this afternoon. Well, I`m slopping on the "soft peach" thick and fast when I hear an unpleasent breaking glass sound.

You know what`s coming next, right? Yep. Poor Coral Sylvania had been blown off the shelf onto the floor and was now lying there dead in his own glass ?

?

?The thing was a write-off. Dissapointing, dare I say Maddening too, thinking how much they are worth.

Not all is lost however. I salvaged the slightly bent electrode from inside and noticed that my initial "diagnosis" of what it was like was slightly wrong.

Here is a photo I hoped I`d not be able to take...(because I never wanted to break any of these- you see?)

Between the 2 elctrodes is a circular porcelain disc with 3 "tabs" sticking out- those tabs are what keep the 2 electrode halves apart preventing a short.

And here is the amended cross-section diagram from above...

It`s such a shame it had to break like this but I suppose it`s death has been of some benefit to interested collectors who might want to know what`s inside those mysterious milky white globes.

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[This message has been edited by Chris Millinship (edited August 12, 2001).]

Bob Masters · « **Reply #2 on:** August 12, 2001, 08:45:00 pm »

Chris,

What a mganificent first effort ......and then a tragic outcome in the end. Sorry to hear about the loss !
It is quite interesting to know what the insides look like for a lamp whose insides aren't likely to be seen, except by way of the loss you suffered.
Thank you for sharing your information !

......yes..I'm back from the Hills of Kentucky ! Ha Ha Ha.......
-Bob-

Ross · « **Reply #3 on:** August 13, 2001, 05:25:00 am »

Chris,

Thank you very much for your photos and information about these fluorescent bulbs. They still fascinate me - I must bid for some soon. I wonder if any manufacturers will ever consider reviving the idea ?

Very sorry about the breakage but thanks for continuing and posting the interior picture. Were you able to verify if the inside of the glass was just a plain coating or is it in fact a fluorescent material ?

Chris W. Millinship · « **Reply #4 on:** August 13, 2001, 08:33:00 pm »

Were you able to verify if the inside of the glass was just a plain coating or is it in fact a fluorescent material ?

Well I just scavenged a chunk of phosphor coated glass out of the bottom of the bin and held it next to a UV black-light tube. Nowt. But as I pointed out, the orange one has a neon fill which emits a bright orange glow on its own so it wouldn`t surprise me if the orange (coral) one was just a plain white coating to diffuse the light- like that used in some soft-white light bulbs.

But the other colours will certainly have a phosphor coating. No other gases emit those pure bright colours on their own. They need a little helping hand. Yellow and "orchid" (pink) may actually have a neon fill- especially since my pink one is very orangey- like the phosphor is at the end of its life and has degraded letting more neon-orange colour shine though. Blue and green may use argon or Xenon- something to give a less visible discharge but strong on UV- to excite the green and blue phosphors. I don`t have a blue yet but it`s on my wish-list (along, now, with a new Coral too

).

I hope never to break any more of these- after all my job as "curator of the South Wales Museum of Electrical Lighting" (otherwise known as an avid bulb collector

) is to preserve these for the future- not break them. But....should the worst happen.....maybe newcomers that get damaged in the mail? I`ll try the fragments against that Blacklite tube again. Blue and green phosphor may shine quite well...?

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Andy · « **Reply #5 on:** September 05, 2001, 08:10:00 am »

First: Chris, what a pity that this happened... I feel with you...

talking about phosphors, I've got a Question about the UV activity:

I have some Neon/Argon tubes here (From beer advertising signs), some phosphors light up when i hold them under black light, some don't at all.... why??

James · « **Reply #6 on:** September 23, 2001, 10:42:00 am »

Hi Chris, what an excellent effort but such a shame it had to end up that way. Nevertheless, short of someone being able to do an X-Ray its probably the only way we'd have found out what was really inside these bulbs.

Keep the innards though, I was thinking if you are agreeable, it might be nice to re-seal them into a replacement bulb but leave the glass clear, and then re-assemble the base so that you'd have the worlds only clear demonstration Fluorescent Xmas bulb! What do you think?

BTW when testing phosphors under a blacklight or other UV source, you have to do it on bare phosphor, not sealed inside the glass bulb. This is because the glass wall itself will absorb much of the UV before it has a chance to stimulate the phosphor inside. Some lamps/tubes use different glasses though which can absorb the UV rays to a lesser or greater extent. I think this is the reason behind your experiences Andy - some tubes will be made of a glass type that is letting the UV get to the phosphor whereas others absorb it.

James.

Chris W. Millinship · « **Reply #7 on:** September 23, 2001, 11:07:00 am »

Keep the innards though, I was thinking if you are agreeable, it might be nice to re-seal them into a replacement bulb but leave the glass clear, and then re-assemble the base so that you'd have the worlds only clear demonstration Fluorescent Xmas bulb! What do you think?

Great idea! Unfortunately the electrodes are bent and the bottom cylindrical part has become detached as a result of the bulb`s injuries. The bakelite base was also fatally damaged and I no longer have it.

If you wanted to do that though, let`s see about finding a burnt out or badly injured one (anyone here got something like that?), remove the old globe and re-seal it into a new clear globe of the same diameter. Fill with new neon Penning mixture, re-fit the bakelite base and there you have it!

I`ll keep my eyes open for dud Flourescent bulbs, although I won`t hold my breath....

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Tim · « **Reply #8 on:** September 23, 2001, 07:45:00 pm »

Quote

....(anyone here got something like that?) I`ll keep my eyes open for dud Flourescent bulbs, although I won`t hold my breath....

I have a pile of them and probably have at least one dud blue in the pile....

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-Tim
BulbCollector.com
DewCollector.com

The LED Museum · « **Reply #9 on:** July 04, 2002, 04:52:00 pm »

quote:
Originally posted by Chris Millinship:
Were you able to verify if the inside of the glass was just a plain coating or is it in fact a fluorescent material ?

Well I just scavenged a chunk of phosphor coated glass out of the bottom of the bin and held it next to a UV black-light tube. Nowt.

You may need a good source of long UVC to mid UVB to get that phosphor to kick out a few photons. I've tried irradiating the inside of a broken green neon bulb with long UVA and it just sits there all stupid looking, reflecting only the dull purple of the source lamp. If you have a "germicidal" 254nm UVB tube, try that first. If that doesn't work, try shining an ozone-generating dryer disinfecting bulb (I think they produce a 157nm "vacuum UVC" line) on the phosphor of your poor busted Christmas bulb. Ordinary air absorbs this UVC line very well (it's also quite bad for skin and eyes), so you'll have to put the phosphored chunk of dead light bulb glass right up to the dryer bulb and then stand back a foot or so and light it up.

Chris W. Millinship · « **Reply #10 on:** July 04, 2002, 05:13:00 pm »

Hey Craig, welcome to the Bulb Board

Suffering CPF withdrawal symptoms yet?

Thanks for the information. I do have a specialised low pressure mercury lamp tube that is intended for some aspect of industrial printing, it emits some pretty nasty short wave UV (one of those which you don`t look at directly or it`ll burn your eyes out!) and creates massive amounts of ozone too, even when only powered with a 16 watt flourescent tube driver circuit (it is a 1000 watt tube!). Unfortunately the poor dead Flourescent Christmas bulb is long gone but I`ll bear your details in mind should I ever drop another one.

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The LED Museum · « **Reply #11 on:** July 05, 2002, 11:24:00 am »

quote:
Originally posted by Chris Millinship:
Hey Craig, welcome to the Bulb Board Suffering CPF withdrawal symptoms yet?

How could you tell? I couldn't take another day without reading about light bulbs or LEDs, so I started looking for other bulb sites and came across this one.

quote:
Originally posted by Chris Millinship:
Thanks for the information. I do have a specialised low pressure mercury lamp tube that is intended for some aspect of industrial printing, it emits some pretty nasty short wave UV ... and creates massive amounts of ozone too,

If you can smell ozone and there isn't any external arcing, you're definitely getting the 157nm "vacuum UV" line (CORRECTION: this is 184.9nm). Good certainty you're also getting the strong 254nm "germicidal" line too; and I'm pretty certain one of them will excite phosphors used in fluorescent lamps. The envelope of your Hg tube is probably quartz (most are) which is relatively transparent to all common UV. If you bust another one of those Christmas bulbs (and heaven forbid that should ever happen again), lay the pieces on your bench, phosphor side facing up, and give them a shot of that mercury tube of yours. Bet they'll light up like a.... Christmas tree.

N.B. The 184.9nm UVC line only travels a few feet (I'm fairly sure no more than yard) in normal air, as air is somewhat opaque at those wavelengths. You may need to mount your tube close to your broken bulb bits if UVC is what activates that particular phosphor.

[This message has been edited by The LED Museum (edited July 05, 2002).]

[This message has been edited by The LED Museum (edited July 05, 2002).]

Chris W. Millinship · « **Reply #12 on:** July 05, 2002, 05:46:00 pm »

Well Whuddya know? Ol` stoopid here just blew a green neon indicator lamp to bits. It was one of those with the plastic lens and "MES" / E10 screw base, for industrial panel indicator lamps. I thought it had an integral resistor for 240 volt. I was wrong. It let out it`s supply of magic smoke in dramatic fashion, and shot the plastic lens cover accross the room.

Well, I recovered the injured bulb from within, and tomorrow (cos it`s late now and I havn`t got all the required parts nearby) I`ll crack it in half (it`s already cracked but still in one piece for now) and try it out placed next to this low pressure Mercury lamp. see if the little thing will glow or not. Assuming my screwy old vidcam will work, I`ll post a picture here too. Well why not....?

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Chris W. Millinship · « **Reply #13 on:** July 05, 2002, 06:08:00 pm »

For the benefit of the other bulb board members:

CPF stands for Candlepower Forums, a flashlight enthusiast`s discussion board that I frequent. Craig, aka the LED Museum, is also a very active member right from the earliest beginnings of CPF, and it is mainly through CPF that we know each other.

Craig`s main web site is at http://ledmuseum.org and Candlepower Forums can be found at http://candlepowerforums.com (when it goes back online following some upgrades these last few days).
Not much, if anything, in the way of historical lighting, but very interesting for the enthusiast of modern "portable illumination technology".

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Alan Franzman · « **Reply #14 on:** July 21, 2002, 01:27:00 am »

Hi Chris,

I have a similar problem to the one that sent you on this little adventure - a rare blue Sylvania Fluorescent Christmas bulb whose base was loose. Unfortunately I didn't notice it until the globe was pulled out about 8 inches from the base, unwinding the resistor. It seems the old 50/50 solder they used on the lead from the globe to the screw shell isn't very strong so it pulled right out. Fortunately the wire of the resistor didn't break and I was able to take some measurements, even with the bulb lit in this partly disassembled state. BTW, the wirewound resistor's core is just a bundle of fiberglass strands.

For my blue bulb, the resistance is 1.5k ohms. My line voltage is 118VAC. The bulb drops 68 volts and the resistor wire 50. This gives a current of 33.33mA. So the resistor burns 1.667W while the gas ( presumably argon) in the bulb uses 2.267W for a total of 3.933W - a bit less than the 5W printed on the base, but higher line voltage will of course result in more power wasted by the resistor.

From what little I can see of it, the electrode structure is the same as your less fortunate example. I also agree that the bulb coating does not appear to be a phosphor at all, making at least these two colors pure gas-discharge rather than fluorescent.

Right now I'm kind of stuck as to what to do about this bulb's condition. I thought of putting a new resistor in the base but all I can come up with at 2W rating is a standard flameproof, much too big to fit in the base along with that long glass stem (my bulb has a much longer stem than yours did). If I could think of something to rewind the wire onto that's solid, nonconductive, and heat resistant I'd rewind it. The original fiberglass bundle separated into 3 sections and is too flexible to hand-wind onto anyway. Judging by the calculated power dissipation and toasty color of the original braided outer sleeve, it definitely needs to take some heat.

Any ideas?

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Alan "A.J." Franzman

Email: a.j.franzman at verizon dot net

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