Greetings from Amsterdam

[Wunderkammer]

Hello Forum,

My name is Michel and I have a small cabinet of curiosities in my office. There are taxidermy, tribal art, planetaria, models of steam engines anything that fascinates me that I can get my hands on.

Curiosities

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There are also a few electrical and electromechanical things like a collection of lighthouse bulbs, including an original lamp holder, a thermo flash relay, an inertial navigational platform from a Starfighter, including a custom made gimbal controller and since some weeks a small Nevelin mercury arc rectifier in its original box. The MAR is in working condition with its vacuum intact. The person who I bought it from, had made an installation to make it 'run' two phase, while in fact it is meant for three phase.

Two phase

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Therefore I hope there is someone here who recognizes the type (see attachment), and can help me with its specs. I found an image on flickr of one in an abandoned cinema that I think is exactly the same (it's only facing the other way), just like mine it needs to be tilted to start it. I will include that image. Greetings, Wunderkammer

Nevelin in cinema

Nevelin arc small.jpeg (117.41 KiB) Viewed 53340 times

[Kevin Wood]

Welcome, Michel. Some very nice curiosities you have there!

Kevin

[mcmurdo]

that's a nice cosy office!

[Lucien Nunes]

Hi Michel

Hello and Welcome. That is a nice bulb you have and it's great to see one lit up and working in someone's home. I like the Nevelins, they seem to be reliable and quite resistant to seal failures. Our 'home bulb' is a Nevelin too, in a bi-phase Unit-Arc-style Nevelector cinema projector rectifier.

The picture of a bulb in situ - I will have to check this but I think it was at Bexhill-on-Sea - shows one of two bulbs in a cabinet. I did hope to salvage that installation when the building was developed but it was not possible in the end. They used magnetostriction start, where a heavy transformer pumps a high current through the narrow neck of mercury, causing it to separate into unconnected pools between which the ignition spark occurs. It looks to me like your bulb uses the same layout but arranged for tilt-start. Our friend and collaborator Jeffrey has a somewhat larger 3-phase Nevelin with the same configuration.

I am afraid I can't help with specs at the moment. I have some brochures from Nevelin but nothing that gives specific data such as current and voltage ratings or decodes the part numbers. When I have a minute I will post some more Nevelin pictures where I do know the ratings, for comparison...

Lucien

[Wunderkammer]

Hello,

Thank you for your replies.
The MAR in the cinema was in the Glen Royal building in Shipley, which was demolished after a fire in 2013.
I believe that the photos in the following article were made in 2010:
https://www.derelictplaces.co.uk/main/l ... ipley.html
I think this MAR was started by tilting it, you can tell by its frame.

Together with a girlfriend I'll make a public-safe installation for my MAR and I'll keep you updated if you like?
The way the installation is now, is not safe (electric shock, UV and bulb-breakage), so I've stored the MAR in its original crate, until I have all the elements needed to run it 3 -phase.

Michel

[ppppenguin]

Lucien referrred to my bulb which is still sitting rather neglected. http://www.borinsky.plus.com/mars.html

I am still planning to make a 2 phase rig, using a welding transformer and a couple of hefty silicon rectifiers. Michel, what circuit did you use for 2 phase operation?

[Wunderkammer]

@ ppppenguin
For two phase operation you'll need a transformer with a center tap, to split your AC into two AC supplies that are 180 degrees out of phase with eachother.

[ppppenguin]

@Wunderkammer, you're describing a bi-phase rectifier which will undoubtedly work. I was proposing a bridge rectifier with the MAR as 2 of the diodes and silicon for the other 2. This ought to work just as well and doesn't need a centre tap.

[Wunderkammer]

@ ppppenguin
Hi, I never tried a MAR as part of a bridge rectifier.
I'm not sure if the MAR would stay 'alive' in that set up.
The balance for it to do so is quite brittle.

Do you have information about your MAR, on what Voltage it is meant to work?

Some time ago I filmed one of my MARs (there are three in my collection now),
with my phone in slow motion and this film I made even slower in a film editting program,
so one can see the MAR going through its three phases.
Realize that the firing up of one of the arms happens fifty times in a second.
You can also see that the plasma stream is never totally away, so the arms keep eachother alive:

https://vimeo.com/259476819

[ppppenguin]

I don't have any more info about my MAR.

It is common to use MARs with 2 anodes as a biphase rectifier. At each zero crossing the current flowing at one anode stops and the current at the oter anode starts. I cannot see how both anodes would conduct at the same time. A bridge configuration is no different, except for the forward voltage drop of the silicon which I hope would be negligible.