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Author Topic: Nernst lamps  (Read 24985 times)
elShoggotho
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« Reply #75 on: January 09, 2012, 11:26:28 pm »

I found that I might need a thinner glower. It conducts electricity just fine, just not enough. Too high resistance.
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Tower
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« Reply #76 on: January 13, 2012, 05:21:16 am »

ITS ALIVE!  

Total burn time at this moment......43 minutes and holding steady.

Spoiler (click to show/hide)


1x2mm ceramic glower in Nichrome holders with a 100watt lightbulb as a resistor.

It works, although I'm not sure what's putting out more light, the glower or the light bulb resistor.

Now the glower problem is solved, what about that bloody resistor problem?

As predicted, nichrome wire did not work, not even when I used several meters of the stuff, it is nice to have for making holders though so its not a complete waste.

Also of interest, a 500watt halogen bulb did not work either, the glower blew up as if there was no resistor at all.

So really folks, how do we make a resistor that will do the job? surely in this day and age there must be something better than iron wire in a hydrogen bulb?
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elShoggotho
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« Reply #77 on: January 13, 2012, 05:29:00 am »

In this day and age, you could make a current limiter with transistors, specifically MOSFET. Also, use a 100 watt bulb. 500 is way too much.
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Tower
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« Reply #78 on: January 13, 2012, 08:10:28 am »

Just tried lighting the glower with a match, and hey, it works! I have to hold the flame under it for a few seconds but it does work!

Total burn time: aprox 3 hours so far.
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Miss Groves
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« Reply #79 on: January 13, 2012, 02:52:22 pm »

Just tried lighting the glower with a match, and hey, it works! I have to hold the flame under it for a few seconds but it does work!

Total burn time: aprox 3 hours so far.

THAT is very awesome!
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Tower
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« Reply #80 on: January 18, 2012, 08:48:58 am »

More experimentation tonight.

A rheostat...aka, light dimmer does not work as a resistor.  Its impossible to get it at the right level, its either too low and the  burner goes out after a few moments, or its too high and it runs away and blows up after a few minutes.

An electric toaster AND a rheostat does work, the toaster by itself is not enough but dimmed down it does stabilize the circuit. Unfortunately its rather bulky, even with all the wire removed and wound up its still pretty awkward and produces a buzzing sound that is most disagreeable.

A 25watt soldering iron by itself works but provides too much resistance and the glower is very dim.

I'm thinking of playing with the soldering iron some more, there may be something there that I can use.  I would actually give the iron/gas resistor a try but I haven't been able to find a source for pure iron wire.

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Siliconous Skumins
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« Reply #81 on: January 18, 2012, 09:51:45 am »


A rheostat...aka, light dimmer does not work as a resistor.  Its impossible to get it at the right level, its either too low and the  burner goes out after a few moments, or its too high and it runs away and blows up after a few minutes.

An electric toaster AND a rheostat does work, the toaster by itself is not enough but dimmed down it does stabilize the circuit. Unfortunately its rather bulky, even with all the wire removed and wound up its still pretty awkward and produces a buzzing sound that is most disagreeable.



Uhm, I think the problem you have there is that the light dimmer is NOT a rheostat. A light dimmer is a type of chopper circuit that uses a thyristor to turn on and off the current a a certain point in the AC waveform, thus giving the apparent effect of a lower or higher voltage. A proper rheostat would work just fine, it's basically a big variable wire wound resistor - pretty much the same thing as what the toaster is doing in your circuit. In this use it's acting in a similar way to a ballast in fluro light.

If you search for the term "barretter" you will find the type of iron-hydrogen resistor you are looking for (a quick google revealed a couple of antique ones on fleabay), here's one that's reasonable in price:


But it might just be easier to find a more common ballast resistor an use that. Not as nice as making your own, but a hell of a lot quicker.  Wink

SS
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SPBrewer
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« Reply #82 on: January 18, 2012, 10:12:09 am »

I would actually give the iron/gas resistor a try but I haven't been able to find a source for pure iron wire.


Perhaps a local metal shop could turn a piece of Iron in a lathe to produce some "wire" that way.

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elShoggotho
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« Reply #83 on: January 18, 2012, 10:28:33 am »

You'd need a wire drawing machine to get the wire that thin.
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Miss Groves
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« Reply #84 on: January 18, 2012, 03:45:59 pm »

You'd need a wire drawing machine to get the wire that thin.

a agree, a draw plate would be the most effective way
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Khem Caigan
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« Reply #85 on: January 18, 2012, 04:04:56 pm »

I see quite a few sources for "iron wire" on the
Interweb - for example:

Cold Drawing Wire
http://tinyurl.com/7c6p95k
@Anping County Longbang Metal Co., Ltd.

What gauge are we talking about?
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Tower
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« Reply #86 on: January 19, 2012, 03:05:04 am »

The problem is finding pure iron wire.  Almost all wire sold as just "iron" wire is actually mild steel.
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Siliconous Skumins
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« Reply #87 on: January 19, 2012, 05:07:37 am »

What about chemical  / lab supply companies, Seems to me to be a likely source of pure iron wire.

As long as you don't overheat the mild steel wire, it should work (though it has near double the resistance of Iron).
Can I ask, why do you want to build the Iron-Hydrogen barretter? Is this for authenticity reasons, aesthetics, or just because you want to try?? 

Why not build it with tungsten wire, it's easy to get hold of, and in suitable lengths (resistance is about 40% less than iron) will work every bit as effectively as the iron wire would - it's basically what the light bulb used by others is doing. As for the hydrogen, it's only there to act as an inert heatsink gas for the wire, it won't matter if you use tungsten or iron.

SS
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Tower
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« Reply #88 on: January 19, 2012, 09:43:00 pm »

Quote
Can I ask, why do you want to build the Iron-Hydrogen barretter? Is this for authenticity reasons, aesthetics, or just because you want to try??

Mostly because I don't know what I'm doing so I figure that using what they used is a good place to start. My Nernst lamp project is about on the level of a cargo cult artifact since electrical engineering was not one of the things I ever bothered to learn. Basically I feel that if I can make something that looks like a Nernst lamp then maybe it will be a Nernst lamp.

But this is how my thinking goes:

If mild unshielded steel would work they would have used it.  I suspect that any steel wire thin enough to act as a resistor will be heated hot enough to oxidize very quickly.

I haven't used tungsten because I don't have any...and again, I think that if it was thin enough to work it would be too hot to use without a gas or vacuum shield.

Because the hotter the Nernst lamp gets the more current it draws, which makes it hotter still and leads to a runaway reaction that blows up the ceramic I think that you must have some king of a resistor that not only creates resistance but increases its resistance with current, aka the lightbulb or some other filament that is heated by the current and has an opposite response to the ceramic glower so that the lower the resistance of  the glower becomes, the greater the resistance of the resistor element is so that they two elements can balance themselves out.

Now, anyone with real electrical knowledge is no doubt laughing at me right now but in effect, I am trying to re-invent the wheel because I don't know enough about roads to even look up the right kind of wheel Smiley

Seriously though, if anyone actually knows what is going on I would welcome any help. Ideally the resistor would be something as simple as a short length of some kind of wire but I really have no idea what I am looking for, just a few observations based off some crude experiments and what other people have done.
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elShoggotho
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« Reply #89 on: January 20, 2012, 02:16:03 am »

I found some barreters on ebay. Rather than risking an explosion by playing around with hydrogen, I'll buy one of appropriate capacity. They come in Edison screw, octal socket and special versions.
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Mr. Consciousflesh
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« Reply #90 on: January 22, 2012, 08:50:37 pm »

Why do I want to build my own Iron-Hydrogen resistor ? Probably because I want to know if I can do that Smiley  Unfortunately I stilll wasn't able to locate source of suitable wire. It has to be pure iron wire , since the thermal resistance coefficient of the steel is lower than the one of the pure iron . The biggest problem is with the wire diameter which should be in the range of 0.1-0.2 mm . The lab supply companies doesn't have this kind of wire on stock but I will still be looking for it.

Meanwhile I finished my automatic Nernst lamp :

Spoiler (click to show/hide)


Spoiler (click to show/hide)

Spoiler (click to show/hide)

Spoiler (click to show/hide)

The heaters work with 24V , and are automatically disconnected by the relay and current sensing resistor visible on the second picture.

The glower is powered from the separation transformer using the electronic current limiter shown below :

Spoiler (click to show/hide)

It can be set in the range of about 0.1A to 0.6A  and works up to 300V . Here is a schematic if you want to replicate it :

Spoiler (click to show/hide)
« Last Edit: April 19, 2016, 10:53:54 pm by Mr. Consciousflesh » Logged

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« Reply #91 on: January 23, 2012, 02:27:20 am »

Way cool!  Or, should I say "That's HOT"!

I was wondering about the Hydrogen.  Was it used because it was easier to produce?  Perhaps, as with Zeppelins, Helium would work as well.
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Siliconous Skumins
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« Reply #92 on: January 23, 2012, 09:08:48 am »

Why do I want to build my own Iron-Hydrogen resistor ? Probably because I want to know if I can do that Smiley  Unfortunately I stilll wasn't able to locate source of suitable wire. It has to be pure iron wire , since the thermal resistance coefficient of the steel is lower than the one of the pure iron . The biggest problem is with the wire diameter which should be in the range of 0.1-0.2 mm . The lab supply companies doesn't have this kind of wire on stock but I will still be looking for it.



Yup, that's the same reason I need to do anything.  Wink

The Iron wire may be the only real problem with building the Iron-Hydrogen resistor, I can't for the life of me think of any other possible suppliers of it. I did however find out two possibly interesting facts during a rather large google search - apparently the screen mesh door / window stuff that is used a lot in the USA, is made from "Nearly pure iron" (according to a post on a blacksmithing forum!), also from the same topic on the forum, iron welding rods are mostly pure iron (the other elements are added via the flux). I looked up a couple of safety data sheets for some welding rods, a couple of them seem to back this theory up. You would need to figure a way to draw out the welding rod into wire however...  Undecided




Way cool!  Or, should I say "That's HOT"!

I was wondering about the Hydrogen.  Was it used because it was easier to produce?  Perhaps, as with Zeppelins, Helium would work as well.

As I recall, Hydrogen has the largest specific heat capacity of the gases, it also has a small molecular size and the lowest molecular mass. This gives it a high thermal conductivity. I believe that Helium is around HALF that of hydrogen, though it is still much higher than other gases. However, Helium has a very small molecular size, and the molecules can even escape through solid materials over time - including glass (I have a dead HeNe LASER tube due to this problem) Smiley


SS
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J. Wilhelm
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« Reply #93 on: January 23, 2012, 09:46:39 am »

Quote
Can I ask, why do you want to build the Iron-Hydrogen barretter? Is this for authenticity reasons, aesthetics, or just because you want to try??

Mostly because I don't know what I'm doing so I figure that using what they used is a good place to start. My Nernst lamp project is about on the level of a cargo cult artifact since electrical engineering was not one of the things I ever bothered to learn. Basically I feel that if I can make something that looks like a Nernst lamp then maybe it will be a Nernst lamp.

But this is how my thinking goes:

If mild unshielded steel would work they would have used it.  I suspect that any steel wire thin enough to act as a resistor will be heated hot enough to oxidize very quickly.

I haven't used tungsten because I don't have any...and again, I think that if it was thin enough to work it would be too hot to use without a gas or vacuum shield.

Because the hotter the Nernst lamp gets the more current it draws, which makes it hotter still and leads to a runaway reaction that blows up the ceramic I think that you must have some king of a resistor that not only creates resistance but increases its resistance with current, aka the lightbulb or some other filament that is heated by the current and has an opposite response to the ceramic glower so that the lower the resistance of  the glower becomes, the greater the resistance of the resistor element is so that they two elements can balance themselves out.

Now, anyone with real electrical knowledge is no doubt laughing at me right now but in effect, I am trying to re-invent the wheel because I don't know enough about roads to even look up the right kind of wheel Smiley

Seriously though, if anyone actually knows what is going on I would welcome any help. Ideally the resistor would be something as simple as a short length of some kind of wire but I really have no idea what I am looking for, just a few observations based off some crude experiments and what other people have done.


That is already beautiful, sir.  If that is not Steampunk I don't know what is.  Great looking as a ceiling / wall lamp under a transparent glass dome.
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Miss Groves
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« Reply #94 on: January 23, 2012, 12:06:14 pm »

or under an oval dome as a table lamp.
beautiful
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« Reply #95 on: January 23, 2012, 09:49:25 pm »


Spoiler (click to show/hide)


Wow!  Shocked  Functional and beautiful. Amazing work!
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DrArclight
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« Reply #96 on: January 23, 2012, 10:47:32 pm »

On the subject of high-power current limiting, you might look at Tesla Coiling sites for some inspiration.  There are a lot of designs ballasts that can carefully limit current.  There are several categories:

Resistive:  As the name implies, this method uses a resistor of one form or anther to limit the current and usually dissipates the excess current as heat.  I've seen water heater elements in in a bucket, carbon rods in water/salt water, plain carbon rods, or pencil leads, light bulbs, etc.

Reactive ballasts are more efficient because they do not change as much energy into heat, but only work for AC voltages.  These fall into the following two categories:

Capacitive:  This method uses capacitors to limit current by placing a string of capacitors of sufficient rating in series with the load.  Some Tesla Coil ballasts use microwave oven capacitors on the HV side as a ballast, but they can be used on the input side too.  Remember that placing capacitors in series reduces the capacitance but increases the voltage rating.  Putting them in parallel increases capacitance and leaves voltage rating unchanged. (Series = 1/Ct = 1/c1 + 1/c2 +...1/cn)

Inductive:  This method places an inductor in series with the load.  The inductor can be as simple as a coil of wire, an appropriately sized transformer, a custom-wound inductor, etc.

Here's a nice site for calculating the reactance (in ohms) of inductors and capacitors:  http://www.electronics2000.co.uk/calc/reactance-calculator.php
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SPBrewer
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« Reply #97 on: January 24, 2012, 07:45:22 am »

I've looked through my "Scientific American" magazines and the patents, but I can't seem to locate the specifications for the length and diameter of the iron wire.  Have I missed something, or has it ever been defined?

Oh, here are some of the Nerst patents I have been able to find.
652,626; 685,724 - 685,731 inclusive; 685,512 ; 906,550

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elShoggotho
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« Reply #98 on: January 24, 2012, 10:22:05 am »

The original barretter was a standard model. You just got it for the specifications you needed. If you know your electrical engineering, you can calculate it yourself.
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Khem Caigan
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« Reply #99 on: January 24, 2012, 03:00:18 pm »

I've looked through my "Scientific American" magazines and the patents, but I can't seem to locate the specifications for the length and diameter of the iron wire.  Have I missed something, or has it ever been defined?

Oh, here are some of the Nernst patents I have been able to find.
652,626; 685,724 - 685,731 inclusive; 685,512 ; 906,550


Here is a link to a patent for a Nernst lamp on
FreePatentsOnline:

Incandescent Nernst Lamp
United States Patent 2120527
Inventor: Michael Parisi
Publication Date: 06/14/1938
@FreePatentsOnline
http://www.freepatentsonline.com/2120527.pdf

And here's a link to a patent for a crucible
furnace co-patented by Nernst :

Electric Furnace
United States Patent 684296
Inventor: Walther Nernst & Ludwig Glaser
Publication Date: 10/08/1901
@FreePatentsOnline
http://www.freepatentsonline.com/0684296.pdf

As for the diameter of the iron filament :

" The size of the iron wire used in our standard ballast
is exceedingly small, about .045 of a millimeter, or
less than two one-thousandths of an inch
, and this
is somewhat smaller than a human hair.

To prevent oxydation of this fine wire, it is enclosed in
a small glass envelope, which is filled with an inert gas,
the complete ballast resembling somewhat a miniature
incandescent lamp. "

~ from:

Nernst Lamp
by Murray C. Beebe
@Nernst.De
http://tinyurl.com/6qr2t8z
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