866 Mercury Vapor Rectifier as Novelty Lamp

[threeneurons]

I went to the TRW swap meet on Saturday, and picked up a 866 mercury vapor rectifier. The thing has a 2.5V 5 amp filament. Good thing I had this large transformer in my stash with a 2.1V tap. Needed less than 50V to light it up, and get the emission up to get more than 50mA thru. Tube is rated for 250mA max average.By sticking a 2200uf cap across the the tube, plate to cathode, it turns into a relax oscillator. Tube drop is only 11V. I never had a relax osc, that couldn't bite me. Even though this rectifier was intended for use in power supplies capable of delivering thousands of volts, this circuit is quite harmless, until the glass breaks:

http://www.dailymotion.com/video/x10b9ux_866-rectifier-as-relax-osc-flashing-light_tech#.UaXI2tKXSSo

Enjoy

[JohnK]

Much UV leak out do you think?

 

John K

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[Nick]

On Wednesday, 29 May 2013 10:54:58 UTC+1, johnk wrote:

Much UV leak out do you think

You read my mind - I would have thought that this was a real (not imaginary) danger. Nearly all UV is absorbed by the front of your eyes, causing corneal damage, cataracts & macular degeneration. 

I'd really be very careful with this, especially if there are children around - there are reasons that these things were run inside cabinets...

Nick

[Bob Armstrong]

On Wednesday, May 29, 2013 2:54:58 AM UTC-7, johnk wrote:

Much UV leak out do you think?

 

  Ordinary glass (i.e. the tube envelope) is opaque to UV.  That's why UV lamps have to be made out of quartz.

 

  Don't break it, though!

 

Bob

[Nick]

UV covers a large wavelength range - from about 400nm to 10nm. It seems that anything shorter than 300nm is regarded as "not good" for human eyes and that normal soda glass absorbs a lot of that, leaving mostly UVA ("long wavelength UV" or NUV/"near UV") as radiation external to the envelope - UVA/NUV can still be dangerous.

[threeneurons]

Any kind of filter I can stick on this thing to block the UV ? Tinted Acrylic ? 

[threeneurons]

http://www.dailymotion.com/video/x10b9ux_866-rectifier-as-relax-osc-flashing-light_tech#.UaXI2tKXSSo

  Dave: I wonder if it is the right UV light for a mineral lamp (compared to that laser pen he carry's)

Okay, we'll surround it with the rocks at Gary's house. That way we'll only get the emissions off the glowing rocks.

[JohnK]

The small QI/Halogen downlight globes come/came in a couple of styles.... one with the small QI/Halogen lamp at the centre of the reflector and open at the front; the other had a glass plate across the mouth / front of the reflector. That glass is for UV reduction. Don't know if it is special glass.

The desk lamps [mainly fancy Italian designer models] that use QI/Halogen globes have been criticised; some have no extra piece of anti-UV glass and apparently with those that do many people leave it off when they replace a globe. [And others said the glass was to stop people touching the halogen globe - because apparently the finger grease causes hotspots and globe explosions (??)].

I only know of this because of workplace reforms some years ago... there was a purge of these 'dangerous' items.

 

I still worry about the use of 2 foot and 3 foot etc 20W/ 40W fluorescent tubes. Especially for bench work up close. There is definitely leakage at the ends where the phosphor doesn't extend. In our kitchen we had a twin 40W fitting with diffuser. There was an identical one in the store room. The diffuser in the kitchen turned to yellow crumbs and collapsed after a few years use. The one in the store room [rarely used] stayed OK. Neither were subject to direct sunlight. I blamed the UV rather than heat.

 

I haven't kept up with LED technology but I do remember reading that a version of white LED used a UV LED with a phosphor.

 

Hope someone comes up with some quantitative details on this subject.

 

John K.

----- Original Message -----

From: threeneurons

To: neoni...@googlegroups.com

..clip..

[Grahame Marsh]

On 29/05/2013 19:02, JohnK wrote:

Much UV leak out do you think?

..clip..

Fo a go-no go test you might look to see if the UV is strong enough to illuminate anything with UV writing on it.  UK currency notes and European passports carry invisible (to the eye) markings that light when lit with even soft UV.  My UV lightbox for PCB manufacture and UV leds are sufficient when held very close.  I'm guessing that USA currency and/or passports might be marked as well?  Or else writing using a UV security marker pen perhaps.

Grahame

[dr pepper]

Paint some of the white stuff on it from the inside of a fluorescent
tube, and you'll have a complicated white light bulb.

They made us wear safety glasses at my last place, they had a lot of
welding bays, and claimed that clear polycarb safety glasses spread
out the uv from a flash enough to largely reduce the effects, so a
piece of clear polycarb might work.

Does the bulb flash like in the vid or is it slower or faster in real
life.

[threeneurons]

Cool, I was wearing polycarbonate safety glasses. Not for the UV, but because I didn't know what kind of abuse the tube had before I got it. The filament dissipates 12.5W, so the bulb gets pretty warm, even without any plate voltage. Mercury coated flying glass seemed like a possibility.

No, it flashes uniformly at ~50mS (~20Hz) rate. That "wobble" in the video, is due to tube flash rate "beating" with the video frame rate. 

I'll have to dig up the spectral characteristics of common clear plastics. I know acrylic is does not transmit IR. That's why laser engravers work well on them. But I'm not sure about the shorter wavelengths.

[John Rehwinkel]

> I'll have to dig up the spectral characteristics of common clear plastics. I know acrylic is does not transmit IR. That's why laser engravers work well on them. But I'm not sure about the shorter wavelengths.

Yeah, I bought a 10.64µm CO2 laser engraver, which had an impressive looking orange acrylic window so you could see the workings. However, that window was cracked when it arrived, and I replaced it with a thick sheet of clear acrylic. The orange coloring does no good at that wavelength (it just looks cool) and it's much easier to see what's going through the new window. Any remaining leakage would be reduced, as the new window is nearly three times as thick as the original.

- John

[Charles MacDonald]

On 13-05-29 02:02 PM, JohnK wrote:
> The small QI/Halogen downlight globes come/came in a couple of
> styles.... one with the small QI/Halogen lamp at the centre of the
> reflector and open at the front; the other had a glass plate across the
> mouth / front of the reflector. That glass is for UV reduction. Don't
> know if it is special glass.

I know I have a couple of floor lamps that use a 300W halogen bulb.
they have a piece of tempered glass in front of the bulb. There was a
recall of some that did not have the glass, but it was not UV but fire
hazard that they were worrying about. The glass keep the bits of the
bulb in place if it is broken while lit. There were some house fires
caused by the lamps without the glass tipping over.


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
http://Charles.MacDonald.org/tubes
No Microsoft Products were used in sending this e-mail.

[Tidak Ada]

Most quality halogen bulbs already have a UV protection coating.
Anyhow, metal-halide lamps also use a disk of tempered glass, primarily to
protect against explosion hazard of the bulbs, but also to filter excess of
UV from the light. You can compare the working of that filter with that of a
photographic UV-filter (not the pink haze filter, widely used in the US).

eric

-----Original Message-----
From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On
Behalf Of Charles MacDonald
Sent: vrijdag 31 mei 2013 6:14
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] 866 Mercury Vapor Rectifier as Novelty Lamp

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[threeneurons]

Got rid of the big iron. I built a little TL494 push-pull switcher, that outputs ~2.5Vrms @ 30KHz. It also generates +25V for the plate voltage. 

http://www.dailymotion.com/video/x10pkvq_886-rectifier-on-switching-supply_tech

I used a different camera, and changed the blink rate on the relax osc, to minimize the "beat" artifact, on the video.