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digital_dreamer
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Rectifier?
digital_dreamer   10/8/2013 12:13:00 PM
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Given the specs and the use case, I'd say a rectifier. The tube looks very simple, but I can't see the cathode or anode. What's with all the "empty" space?

MAJ

bobdvb
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Re: Rectifier?
bobdvb   10/8/2013 12:33:25 PM
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It is a Mercury Arc Valve rectifier:

http://en.wikipedia.org/wiki/Mercury-arc_valve

http://www.electricstuff.co.uk/mercarc.html

I've seen pictures of them in abandoned buildings:

http://underground-history.co.uk/belsize.php

Rcurl
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Re: Rectifier?
Rcurl   10/8/2013 3:59:56 PM
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Max The Magnificent
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Re: Rectifier?
Max The Magnificent   10/9/2013 11:07:13 AM
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@Rcurl: Take a look at this one!

It's like a work of art!!!

David Ashton
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Re: Rectifier?
David Ashton   10/8/2013 5:14:29 PM
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@bobdvd - the link to the underground history pics had a remark that confirms what I seemed to remember - that they emit heaps of UV and it's not good to look at them for long.

bobdvb
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Re: Rectifier?
bobdvb   10/9/2013 6:20:09 AM
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I was wondering if they also emmit significant x-rays as well? Given the quantity of electrons involved I can't imagine their not being emission!

Edit: I read somewhere that the voltage is too low for x-ray emission.

Max The Magnificent
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Re: Rectifier?
Max The Magnificent   10/9/2013 11:06:16 AM
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@bobvd: I've seen pictures of them in abandoned buildings...

Wow!!! I would have loved to have seen that...

Yog-Sothoth
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Re: Rectifier?
Yog-Sothoth   10/9/2013 6:54:48 AM
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Yes, it's a mercury arc rectifier. When I was a kid I recall seeing one in the Scince Museum in London, and it was working at the time. Emitted a blue-green glow when it was working. The cathode was a pool of mercury at the bottom, the anodes were (I think) carbon rods in the tubes around the sides.

Max The Magnificent
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Re: Rectifier?
Max The Magnificent   10/9/2013 11:04:49 AM
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@digital_dreamer: Given the specs and the use case, I'd say a rectifier.

That's my guess -- a mercury arc valve rectifier -- I would LOVE to have this in my office!!!

Caleb Kraft
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Arc Rectifier
Caleb Kraft   10/8/2013 4:20:11 PM
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That's an Arc Rectifier! I doscovered them in 2010 and was instantly in love. They glow a wonderful blue green!

Here's my article from back then.

Caleb Kraft
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Re: Arc Rectifier
Caleb Kraft   10/8/2013 4:21:23 PM
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Here's a direct link to a video of one lit up. Man, so amazingly pretty.

Rcurl
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Re: Arc Rectifier
Rcurl   10/8/2013 5:11:25 PM
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These guys are a lot more complicated than I realized. I found this quirky video with an in-depth explanation of how they work: http://www.youtube.com/watch?v=6Oq9VC94vbw

After looking at videos of these tubes in operation, I am amazed at the erratic flickering of the arc.  I would guess that the output is pretty noisy! 

Max The Magnificent
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Re: Arc Rectifier
Max The Magnificent   10/9/2013 11:08:35 AM
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@Caleb: Here's a direct link to a video of one lit up. Man, so amazingly pretty.



It's like a mad scientist's dream -- I WANT ONE!!!

David Ashton
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Re: Arc Rectifier
David Ashton   10/9/2013 5:42:11 PM
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@Max...I'm sure Crusty would know something about these, where is he?

Max The Magnificent
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Re: Arc Rectifier
Max The Magnificent   10/9/2013 6:13:26 PM
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@David: I'm sure Crusty would know something about these, where is he?

The way Crusty talks, he was probably around before Mercury Arc Rectifiers were invented. The last I heard he was basking at Crusty Mansions -- I'll give him a ping and point him at this column.

Crusty1
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Re: Arc Rectifier
Crusty1   10/10/2013 3:06:09 AM
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@David , Max,

In Crusty Mansions we are almost solid state now, just a few electromechanical activators remain, I wonder just how many electromechanical items we still use, but do not notice any longer in the average home?

I have come across Mercury Arc Rectifiers in my time, as these were the main way for rectifying huge amounts of AC traction power for Londons Underground trains. Sadly I never had a qualification to work with traction power, so I only came in contact with them when it became a problem to be solved by the LTE Research Laboratory.

Brilliant things in all ways, to long with the metal doors of the cabinets open and you got a brilliant sun tan, and what an unearthly glow to walk towards.

The DC power control resistors slung under the trains were something else and I regularly used the cast iron elements for dropping power from the DC main to run some of my more arcane experiments at the Laboratory.

 

 

David Ashton
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Re: Arc Rectifier
David Ashton   10/10/2013 5:38:31 AM
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@Crusty... "I only came in contact with them...."   Which is still a lot more than most of us.   Nice comment about the suntan.   

I've watched a couple of the video links given...but none has satisfied my curiosity - what is a typical forward voltage drop for there devices?

" I wonder just how many electromechanical items we still use..."   A surprisingly large number, I would say.  My washing machine (+/- 10 yrs old) still has a few relays.  Most household circuit breakers are still EM devices.  And the average printer, of course, is full of them.

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