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Author Topic: Ediswan whatzit?  (Read 8918 times)

Offline Tim

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Ediswan whatzit?
« on: June 20, 2002, 09:51:00 pm »
Looking for some information on this one.  It's a tubular bulb fitted with a standard Edison screw base.  The other end has a brass cap with a large thumb screw for an electrical connection.  Inside are three closely spaced electrodes that are connected to the top cap and the screw base.  It has a neon atmosphere and the rods glow dim orange when in the presence of high voltage.  Can anyone ID this thing?  Voltage regulator?  Lighting arrestor?

 

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Tim
Kilokat's Antique Light Bulb Site
Mountain Dew Collectibles, Volume I

[This message has been edited by tim (edited June 20, 2002).]

Offline Chris W. Millinship

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Ediswan whatzit?
« Reply #1 on: June 21, 2002, 03:17:00 pm »
Interesting little item Tim. I believe I have the offer of something very similar at the moment from a friend in Austrailia, being described as a lightning arrestor.

But would such a thing be strong enough to dissipate the energy of a lightning strike on power cables? I wonder.
That large bolt-like part on top does look like it could be hooked through a wire to a substantial earthing point though, perhaps with the screw base in a powered light socket to protect against relatively small spikes and surges. The electrode wires look kind of thick, like a few tens of amps could be handled.

Or- could be some sort of switching device? I`ve heard of "gas relays" before- apparently three terminalled things utilizing neon gas, and acting perhaps like a transistor? Never seen one though and I don`t know how they work, but it`s a start...?


 



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Offline Tim

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Ediswan whatzit?
« Reply #2 on: June 21, 2002, 03:36:00 pm »
Hey Chris,

Ya it's the same lamp (tube?) from the same source (they had a few I think), mine just came the other day and it has me curious now as to what exactly it is.  Thanks for the observations.  I wish it had a part # stamped on it to reference.

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Tim
Kilokat's Antique Light Bulb Site
Mountain Dew Collectibles, Volume I

Offline James

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Ediswan whatzit?
« Reply #3 on: June 22, 2002, 08:53:00 am »
Hi Tim / Chris,

I am no expert in tubes like this but I do know that Ediswan was very big in making Telephone Line Protectors after they merged with Siemens to form Associated Electrical Industries.  Siemens set the original design but their name was dropped in favour of Ediswan after being known as Sieswan for a few years.

Very similar looking tubes, but having two electrodes instead, were wired across the two terminals of a telephone line.  In the even of a fault at the telephone exchange which was common in the old days, the 240V mains could accidentally be sent down the cables to someone's house which would fry their telephone equipment (British Standard phone lines work at 48-50V DC normally).  The idea was that connecting a gasfilled tube across the line would result in the gas breaking down at around 75V thus protecting the telephone equipment.  Also people who had mains powered phones in their houses (like for powering a speaker, extra bell etc) were prone to their equipment failing and them sending the mains back up the phone line to the exchange, killing the exchange's equipment.  Again in this instance, the gasfilled tube would flash over and protect the line.  Usually they'd only arc for a fraction of a second, allowing a momentary high current flow which would trip out a fuse at the exchange before further damage could be done.  Such tubes were usually filled with a neon-argon or neon-xenon mixture.

Telephone line protectors became much smaller in the 1960's, and these days they take the form of very small gasfilled spark gap tubes just a few mm long which are soldered into the main line box in each house.  They are no longer produced by any of the lamp manufacturers as far as I am aware.

Perhaps your triple electrode tube was some space-saving special used at the exchange to protect two lines, I really don't know but its construction is very similar to the single format tubes!

Best regards!

James.

Offline Electric Bill

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Ediswan whatzit?
« Reply #4 on: June 22, 2002, 10:29:00 pm »
I think James has hit it on the head.  But
I don't see how the tube as depicted would
have protected both lines. I suspect two
were used to arrest each line protected.
Carbon rods were used later, one for each
line. I have run across gas bridges used
in later applications which protected both
sides, but I have never seen such complex
lamps. I think it really interesting how the
Edison base was emploped as the way to make
an electrical connection. Early on it was
used to accept electrical receptacles (plugs), and not only lamps.
The Ediswan is a very interesting specimen
in electrical technology's advance toward
a standard.

Bill


Bill

William K Bunk PhD

Offline Tim

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Ediswan whatzit?
« Reply #5 on: June 30, 2002, 10:42:00 am »
Thanks for insight guys, I would have never guessed its purpose!

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Tim
Kilokat's Antique Light Bulb Site
Mountain Dew Collectibles, Volume I

Offline Hemingray

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Ediswan whatzit?
« Reply #6 on: October 05, 2002, 11:33:00 pm »
Could be one of a few things:

1: A special glow lamp
2: A triode tube(3 elements)
3: A neon arc lamp(refer to 1)
4: Lightning arrestor
5: X-ray component

Just some of my guesses