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The Tesla Thermionic Valve Wireless Energy Transmitting Apparatus

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Firefox

Sun May 10 2009, 04:51AM

Registered Member #1389 Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346

If you're having trouble with nasty looking ends, try using a rope whipping technique to tidy up the ends with some of your twine. Though you may have to undo some of your lacing to get at the affected wires, I imagine. I am enjoying looking at the pictures of the build (and thank you for not using imageshack).

Is that ball going to be sitting on top of your breakout point all the time, or are you going to take it off/put it on when you feel like it? Also, can the mechanical contacts hold up to the RF power passing thorough them, or might they get corona on those surfaces?

Dalus

Sun May 10 2009, 12:43PM

Registered Member #639 Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512

A copper/brass cover for your MOT would make it even nicer. Though it might get hot.

Mads Barnkob

Sun May 10 2009, 04:39PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Its looking great Cesiumsponge!

The amount of dedication to your theme is overwhelming :)

Dalus wrote ...

A copper/brass cover for your MOT would make it even nicer. Though it might get hot.

or simply paint it black, thats what I did with the mot/moc in my vttc, looks good.

Renesis

Sun May 10 2009, 08:08PM

Registered Member #2028 Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319

or simply paint it black, thats what I did with the mot/moc in my vttc, looks good.

I know this is going to make me look like an idiot, but how about electroplating the core with brass or copper? Would that affect the performance of the MOT? It sure would look great.

Cesiumsponge, i havent commented your project yet. What a stunning tesla coil! I love the old style cable lashing, and the choice of materials. I tend to prefer the more modern look, but this has definately caught my attention. Your attention to detail is beyond anything i have ever seen. I cant wait to see it finished.

Edit: What CAD program are you using?

Dr. Drone

Mon May 11 2009, 04:34AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

Hazmatt_(The Underdog)

Mon May 11 2009, 08:47AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

It's looking really good. I would have heatshrunk the crimp lugs to finish off the wire/lug connection with a clean look, but that's just me.

> you don't plate a transformer core. Laminations are electrically isolated with a layer of varnish and are carefully treated so as to reduce eddy currents. If the core were allowed to conduct to each adjoining lamination, enormous currents would build in the core and cause tremendous power loss and quite a bit of heating.

Dalus

Mon May 11 2009, 11:54AM

Registered Member #639 Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512

He could take the MOT completely apart. Clean the varnish of then electroplate it put new varnish on there and reassemble it. Though I have a feeling this would be to much work even for Cesiumsponge.

Dr. Dark Current

Mon May 11 2009, 01:31PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Dalus wrote ...

He could take the MOT completely apart. Clean the varnish of then electroplate it put new varnish on there and reassemble it. Though I have a feeling this would be to much work even for Cesiumsponge.

That would not work, clear the varnish and electroplate EVERY lamination? They are welded together. Or just the core? That would short it out anyways. And the magnetising current of a re-assembled MOT is always monstrous.

By the way, amazing work Cesiumsponge.

Dalus

Mon May 11 2009, 01:51PM

Registered Member #639 Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512

I've seen cores that aren't welded together. It will be a lot of work to strip the varnish of then plate every lamination and revarnish them. Don't know about how much the magnetizing currents would increase not a lot when the core gets put together nicely I guess.

From a practical standpoint it would be a lot simpler to make a housing from a few brass/copper plates.

Cesiumsponge

Wed May 13 2009, 02:33AM

Registered Member #397 Joined: Wed Apr 19 2006, 12:56AM
Location: Western Washington
Posts: 125

Firefox wrote ...

If you're having trouble with nasty looking ends, try using a rope whipping technique to tidy up the ends with some of your twine. Though you may have to undo some of your lacing to get at the affected wires, I imagine.

Is that ball going to be sitting on top of your breakout point all the time, or are you going to take it off/put it on when you feel like it? Also, can the mechanical contacts hold up to the RF power passing thorough them, or might they get corona on those surfaces?

I think it would look quite odd too for my tastes. I redid most of the offending terminals and redid the entire cable lacing job, this time switching to proper cable lacing material. What I used before was a waxed twine, which does work fine, but the proper cable lacing material almost like dental floss, but more waxy and no minty. It was good practice.

As far as the breakout point, I just put the ball on there because it was handy for the photo and I didn't want to jab myself with the sharp breakout point underneath. Which mechanical contacts are you referring to? If something is going to create an electric potential high enough to ionize air, the method of contact wouldn't change anything, unless it was such a poor mechanical contact that it established an arc.

On the MOT:
I once considered doing a brass casing or a gloss black sheet metal case to cover the transformer, much like a tube audio amplifier. However I thought twice and dropped the idea because the premise behind the steampunk aesthetic is to have the guts exposed, to show the mechanical goodness of what's underneath, all the wires, gears, and stuff you normally don't see. Keeping that in mind, I ended up lacquering the MOT a bit to protect it from corrosion. One of the filament transformers is a vintage Stancor so it already looked old with it's coat of shellac or lacquer. The other was a new Magnetek transformer. I actually lacquered it like crazy to give it an off-brown lacquered look as well. The transformers look like transformers as a result, and I just dolled them up a bit to make them look somewhat aged.

[quote]
Outstanding work sir!

One little suggestion that may save a tear down the road is to ensure all connections to the tube are floating (Plate, grid and filaments) as once tube heats up things move and you do not want to hear a tink! This is good as plate cap can float on wire @

Spark On,
Ch

The plate and grid connections actually look a -lot- more rigid than they really are. The bus wire I used has a fair amount of flex and the connections from the tank cap and plate cap are both bolted to the solder tabs on the resistor, which is pretty flimsy. I believe it should be fine with expansion of the glass envelope. I'm fairly certain moving the coil around for transport introduces much more twisting and flex than what the tube will see in stationary operation. I also have some split lock washers on the thumbnuts used on the choke so the connections at the resistor tabs can swivel a bit as I didn't torque the sucker so much that the split rings are completely flattened.

Ironically, on my original 810 VTTC, the plate cap wire actually nearly broke off at the tank cap terminal because the wire was so stiff that after repeated actions of taking off and popping on the plate cap, the wire strands finally broke one by one until it was just hanging there. It was some 20kv+ high voltage wire with hard insulation (not like that flexible silicone GTO wire).

I will keep this in mind though. I've had the filament warming for about an hour and I had no issues, but I do have a couple extra tubes. I am fairly confident on the toughness of these tubes.

The one currently being used is actually my beater tube. I had to use a torch to remove the silver solder on end of the grid cap once. The ceramic spacer piece had the ceramic-glass glue joint break loose, leaving the terminal jiggly since it was only attached to the invar feedthru, which could forseeably lead to the ceramic spacer scraping the glue clean off the glass, then eventually scoring the glass, causing it to fail down the road. I glued it back and re-silver brazed it back on. The cap was a dull cherry red from the heat and I had to use scotchbrite afterwards to clean up the oxidation. These things are pretty tough!

Dr. Kilovolt wrote ...

They are welded.

Yep, mine happens to be welded too. Not just a cheesy tack weld, but two parallel beads down the bottom and two more at the top perpendicular to the laminations. I couldn't seperate the laminations unless I took an end mill and machined a big groove to remove each weld.

Had stuff to do this weekend so I didn't touch the coil at all. I am also planning a dual 810 VTTC in a similar style and got a handful of canister-type mica transmitting caps in the mail, and waiting for my variable vacuum cap (didn't come yet D: ) so I have been sidetracked. I did manage to work on the ground connections today. Ran most of the wires and roughed in the bundles as I want them to break out nice and even to the ground block, as well as fabricated half of the grounding block and tapped the holes (copper is gummy!) This project is fairly simple as far as wiring goes too and its a burden to cleanly route stuff and lace it up. I think I might shoot myself in the face if I had to do cable lacing on something much more complex like Dr. Spark's Quadzilla with all his monitoring and control circuitry.

As long as I put in at least a couple hours a day, this thing should progress fairly quickly. Wiring and the primary are basically the only things left. Now that it's near completion, I've slowed down my pace a bit to smell the roses.

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