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Author Topic: Nernst lamps  (Read 26763 times)
elShoggotho
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« Reply #50 on: December 31, 2011, 03:48:25 am »

Not with hostilities this time though. They used bears last time. Well, a bear.
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SPBrewer
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« Reply #51 on: December 31, 2011, 03:57:47 am »

Not with hostilities this time though. They used bears last time. Well, a bear.

Nerf guns and Airships at 500 yards!  Smiley

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SPBrewer
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« Reply #52 on: December 31, 2011, 04:47:59 am »

  More Nernst info from www.archive.org
http://ia600202.us.archive.org/8/items/nernstgloweritsd00eust/nernstgloweritsd00eust.pdf

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elShoggotho
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« Reply #53 on: December 31, 2011, 05:37:34 am »

If you can get your hands on an iron-hydrogen resistor, you're basically finished. That's the kind of current limiter originally used with the Nernst lamp. Any other stabilized current source will do though.
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Tower
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« Reply #54 on: December 31, 2011, 08:28:09 am »

Quote
As far as I know all the ceramic sharpening tools are made from the alumina ceramic which is one of the best insulators . After some experiments I found that the best way to use the peeler blade is to grind the knife edge of the blade and then to cut it into four parts . The original blade is too long and too wide to be used ad a glower. In my first experiments I used only a half of the blade and after some on-off cycles the glower started to break from the thermal stresses . Now , with a narrower ceramic strip the problem seems to be gone ( at least for now ) . To grind and to cut the blade I use the diamond saw blade and the high speed "dremel-like" tool.

Thanks. I was afraid that the sharpening rod would be alumina but didn't know if that was a common use for it or not.

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Mr. Consciousflesh
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« Reply #55 on: January 02, 2012, 12:00:47 am »

I'm sure there are simple modern counterparts that could be found though?

I can think of over a dozen modern solutions to this problem , but I want to do it the hard way . Even now during the tests I'm using either a tungsten filament light bulb , or a MOSFET based constant current source . Making the iron wire resistor will be real fun and a good prelude to building carbon filament light bulbs and finally my own vacuum tubes . Today I located a source of the thin iron wire and started looking for data necessary to calculate the current limiter.

ps. why on earth does your username make me think of frankensteins monster...

I'm pleased to hear that , but I prefer to think of myself as a brain in a jar Wink

Oh my, the Germans and Polish are about to duke it out again!  Smiley

This is only a small , peaceful , scientific race . Those hydrogen filled balloons and blunderbusses are only for a show , aren't they ? 
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« Reply #56 on: January 02, 2012, 09:06:10 am »

....Making the iron wire resistor will be real fun and a good prelude to building carbon filament light bulbs and finally my own vacuum tubes ....


This is fascinating, wish I had the equipment to do so:

hand making vacuum tubes Part 1

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Miss Groves
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« Reply #57 on: January 02, 2012, 12:51:01 pm »

that is mesmerising...
never seen anything like his 'solder press' (?)
and i love how the glass responds like warm plastic...
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elShoggotho
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« Reply #58 on: January 02, 2012, 05:18:23 pm »

That's a rotary press combined with a small arc welder. The press is from the early 20th century, before the Great War, I think. I have a similar model, without the welder attachment. Also, enjoy that video like you'd enjoy a Bob Ross video. "And a tiny little filament there, and don't forget the plate..."
« Last Edit: January 02, 2012, 05:24:01 pm by elShoggotho » Logged
von Corax
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« Reply #59 on: January 03, 2012, 05:47:06 am »

That's a rotary press combined with a small arc welder.
Arc welder or spot welder?
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elShoggotho
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« Reply #60 on: January 03, 2012, 06:03:45 am »

That's a rotary press combined with a small arc welder.
Arc welder or spot welder?
Most likely spot welder.
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SPBrewer
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« Reply #61 on: January 03, 2012, 10:15:09 am »

I suspect the vacuum pump would be the hardest/most expensive to obtain.

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elShoggotho
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« Reply #62 on: January 03, 2012, 11:00:21 pm »

Back on track: I've got some results! Due to lack of a suitable power source, I couldn't get the glower running. Gotta use the large one next time. Slightly better results with the Kanthal wire. It heats up just fine.
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SPBrewer
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« Reply #63 on: January 05, 2012, 10:01:32 pm »

My Potato Peeler came in from China today!  Will try to control myself and photograph the various steps.  Roll Eyes
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Tower
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« Reply #64 on: January 05, 2012, 11:17:45 pm »

Quote
I suspect the vacuum pump would be the hardest/most expensive to obtain.

Actually there not that bad. $200-$300
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Tower
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« Reply #65 on: January 06, 2012, 03:45:03 am »

My peeler arrived!  I've found that its easy to use a dremel cut off wheel to score the ceramic blade and then use slight pressure to make it break off little chunks about 2mmx8mm. I should be  able to get around 20 elements this size from a single blade.

First experiment using a completely unregulated power source showed that this blade does indeed fluoresce!  It only lasts about 2 seconds before burning through the copper electrode holders but the principle is sound! And the light is brilliant, blinding in fact.

Now I need a good resistor.  First off it seems that the original iron wire in a hydrogen atmosphere shouldn't be too hard to make. Assuming its at atmospheric pressure it seems that a simple cork in the end of a test tube should be sufficient to make a hydrogen chamber. I'm also wondering if nichrome wire would work. It has high resistance and heat tolerance and does not degrade in atmosphere and it would be easy to tailor the resistance by increasing or decreasing the length of wire. Its also pretty cheap.
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Miss Groves
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« Reply #66 on: January 06, 2012, 06:34:30 pm »

was the light nice and steady?
sounds promising.
Nichrome MIGHT work, you'd have to test it or look at the tolerences and data though.
and does anyone actually KNOW if it is at atmospheric pressure?

Anyone got those articles that i saw on ebay about nernst?
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Tower
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« Reply #67 on: January 06, 2012, 11:07:01 pm »

The light started out as a steady yellow glow and then quickly brightened  into a blue white point before the ceramic melted through the copper holder and fell out, no doubt a result of not having a resistor. Its interesting to note that the ceramic did not seem damaged, only the holder.

Nichrome is good up to 1400º C, resistance  varies with length and wire gauge.  It seems that I should be able to play with the length of coil until I get it right. I actually got the idea from seeing it used as the resistor in carbon arc lights.

Do you have any idea how much resistance is needed for a 120 VAC circuit?
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Miss Groves
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« Reply #68 on: January 06, 2012, 11:42:44 pm »

hmm no personal clue but google threw up this stuff:
http://www.allaboutcircuits.com/vol_2/chpt_10/1.html

http://www.bowdenshobbycircuits.info/page7.htm

http://answers.yahoo.com/question/index?qid=20111109221240AAQNoQ5

http://www.physicsforums.com/showthread.php?t=249926

dunno if it'd be of any use but might be worth a look see
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SPBrewer
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« Reply #69 on: January 07, 2012, 05:19:34 am »

was the light nice and steady?
sounds promising.
Nichrome MIGHT work, you'd have to test it or look at the tolerences and data though.
and does anyone actually KNOW if it is at atmospheric pressure?

Anyone got those articles that i saw on ebay about nernst?

I've received my original Jan 11th 1902 issue of Scientific American.  The other two issues are on the way.  It should not be difficult to obtain hydrogen from electrolysis of water.  The issue I have did not specify if the Hydrogen is under pressure or not, but since it is just to keep the iron wire from oxidizing, I don't see any reason for it to be.  This issue shows Nernst lamps with 1, 2, 3, and even 6 glowers.   Candle powers of Nernst lamps are reported as ranging from 50 to 2,000.
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Tower
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« Reply #70 on: January 07, 2012, 05:29:09 am »

Quote
The issue I have did not specify if the Hydrogen is under pressure or not, but since it is just to keep the iron wire from oxidizing, I don't see any reason for it to be.


I agree, its just a shielding gas, pressure shouldn't factor in it at all.

I've ordered some Nichrome wire for my own experiments. I think it should work, fulfilling the same function as the iron wire but without the requirement for a shielding gas.

Its also possible that it could be used as the preheater since one of the  things its used for is heating elements.

I've got to say, its a lot of fun working on a project with other people at the same time who are all trying to do the same thing but in slight different ways.
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elShoggotho
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« Reply #71 on: January 07, 2012, 05:32:08 am »

Ordered some surplus ceramic lustre terminals. Always a good thing to have, and a basic necessity for this.
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Mr. Consciousflesh
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« Reply #72 on: January 08, 2012, 11:55:15 pm »

If you are thinking of using the nichrome wire instead of the iron wire in the current limiter you can forget it. Thermal resistance coefficient of Nichrome is over ten times small than iron's  ( http://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity#Resistivity_of_various_materials ) . I also found some more information about the iron wire current limiters : the wire operates at about 300-600 deg. C , so the pressure of the hydrogen has to be below the atmospheric pressure to lower the heat loss caused by the convection . I also strongly advice against filling the bulb without evacuating if first . Hydrogen mixes with air very well , and your current limiter may explode when powered.

I've found a simple way of testing the ceramic glowers - connect them with a normal light bulb in series . Start with the small bulb - no more than 25W , if the bulb lights up when the glower is heated with the blowtorch change it to a more powerful one until the glower operates well. The tungsten filament light bulb has a similar characteristics to the iron wire current limiter .

In my prototype I made the glower holder from a stainless-steel scalpel blades. You can try Nichrome too . Almost everything else will melt or oxidise at this temperature.
« Last Edit: January 09, 2012, 08:53:31 am by Mr. Consciousflesh » Logged
von Corax
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« Reply #73 on: January 09, 2012, 06:56:32 am »

Err... I assume you meant to say "I also strongly advice against filling the bulb without evacuating if first"?
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Mr. Consciousflesh
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« Reply #74 on: January 09, 2012, 08:57:44 am »

Err... I assume you meant to say "I also strongly advice against filling the bulb without evacuating if first"?

Thanks . I just fixed it . I must have been really tired yesterday to overlook this .
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