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Getting the ball rolling...

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J. Aaron Holmes

Fri May 22 2009, 07:01PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Dr. Spark wrote ...

however, think picture below was made in a week.

Classic! "Old Smokey" LOL! I wonder if that describes first light

Actually, this looks surprisingly like my first coil, with the exception being that I used a NST.

Cheers,
Aaron, N7OE

syntroniks

Fri May 22 2009, 07:29PM

Registered Member #1530 Joined: Tue Jun 10 2008, 03:34PM
Location:
Posts: 32

Dr. Spark made me crack a smile. The topload and tape on secondary is what makes it, I'm sure it made spark just fine though!

Herr Zapp

Fri May 22 2009, 07:46PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Blitzorn -

One additional item ..... you stated that your "xformer" was rated at 7200v/35ma.

These are "odd" ratings for a neon sign transformer.

Are you absolutely sure that this is a conventional iron-core neon sign transformer?

Or is there a possibility that it is a solid-state "gaseous tube power supply"?

You need an iron-core transformer without an internal ground-fault interrupter.

If you're not sure what you have, upload a photo here ...

Regards,
Herr Zapp

Blitzorn

Fri May 22 2009, 09:01PM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

I more than understand that this is a phenomenal amount of work for two weeks, but i have time to spare, some spending money, and i am VERY dedicated to getting it done. It may prove to be too much, but i don't plan to sacrifice safety or funtionality for speed, and if worst comes to worst i'll finish it over the summer and just demonstrate a spark gap or something! I have a nearly complete design on paper, i am still working out the specifics of the capacitor (basically weighing the relative merits and drawbacks of saltwater vs. rolled PP+Foil) and making hardware store visits to determine available gauges of wire, PVC, etc. My current spark gap design is very similar to the richard-quick design with some small modifications. I have all the equipment i need to make a bank of SWC's but i'm not going to start doing that until i know whether it would be easier/smarter to make the rolled cap. I've made all the necessary calculations for the secondary, and only need to decide on a gauge for the primary in order to finish that up. I'm going to make the topload out of ducting, as per stated previously.

Herr Zap - I have read richie burnett's whole page, everything filed under tesla coils on the HvWiki, the DeepFriedNeon site, and much more. I feel like i really need to start accruing parts in order to make calculations based on what i can actually get my hands on instead of designing something with parameters that will be impossible to replicate with available hardware. Thanks for the link to the WINTESLA DL i was having trouble finding it :)

I'm going to make a hardware store visit this afternoon, which should be a big boost forward. Plan on establishing ducting, PVC, and wire gauges.

As for the transformer's "oddness," i'm not sure what to say. I'm 99.9% sure that it is a normal, line filtered, non-GFCI transformer that just has uncommon parameters... Is this going to cause problems? 7200v is well within the expected range of all my other parts and 35mA is not that unusual, also within typical range.

Dr. Spark -

With all due respect to jacob and his ladder, i am nowhere near as interested in it as i am to TC's and, he product is more important than the deadline in this case, but making the deadline would be, well, optimal.

Believers and doubters -
Pics will be up soon, i've already modified a shopvac as part of the spark gap, a symbolic groundbreaking on the project. It's Blitz!

Coronafix

Fri May 22 2009, 11:38PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Try drawing a spark from the transformer, I believe it should either cut out or you won't be able to if it is a solid state one or GFI protected.
With the topload, you can also buy large styrophoam spheres from the craft section of fabric shops. Just coat with aluminium foil. (No there is not too many letters in that word! It's Australia here :P )

Herr Zapp

Sat May 23 2009, 01:23AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Blitzorn -

As far as beginning to acquire parts, a good place to start would be to obtain the wire that you will use to wind the secondary coil. Ideally, you would use enameled magnet wire, between #24 and #28 AWG. Finer wire is harder to wind, at least for your first coil. Conventional plastic-insulated wire can also be used, but because of the insulation thickness you will not get nearly as many turns per inch as you will get with magnet wire.

After you obtain the wire, you will be able to determine how long the secondary coil form will need to be to get the desired 1,000 to 1,300 turns.

Then, determine what kind of topload you will build, and what its dimensions will be. Once you know your secondary wire gage, the dimensions of your secondary coilform, and the dimensions of your topload, you can load these parameters into WINTESLA and find the required the required value of your tank capacitor, and the number of turns in the primary coil to achieve pri-sec resonance. Then, its just a matter of building everything to spec.

Have you been able to verify that your "xformer" is a conventional iron-core transformer, capable of sustaining a continuous 1/4" arc across the HV output terminals?

Regards,
Herr ZApp

Coronafix

Sat May 23 2009, 03:05AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

This is a great calculator.

Blitzorn

Sat May 23 2009, 05:34AM

Registered Member #2128 Joined: Thu May 21 2009, 03:17AM
Location: Seattle, Washington, USA
Posts: 58

I'm still awaiting delivery of the transformer, but with any luck it won't be too long... although i'm starting to have serious doubts. Here's a pic:
mod edit: links corrected. To post a link, just write the URL itself, no link tags needed.

,236419734&formats=0,0&format=0

I referred the Catalogue number to some other sites that (vaguely) suggested to me that it is an "Enclosed, indoor/outdoor, mid-point grounded, electronic gas-tube sign power supply" that has secondary ground fault protection, hard connection, IEC socket, and/or cord connection. I'm not exactly certain what all this implies but i get a sinking feeling. Verify or debunk?

EDIT: I found this as a possible replacement - a bit of a budget breaker for me but i'll do what i have to - Is this a better plan? After some review and noticing the hard to miss reference of hobby use i'm basically set on this...

Should i go ahead and order it?

By the way, thanks a ton for the early whistle blowing Herr Zapp, since it appears your intuition was spot on you probably saved the whole project from falling victim of a novice complacency error. Things may be saved yet!

Herr Zapp

Sat May 23 2009, 08:34AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Blitzorn -

Check your links to the photos; neither of them seem to be functional.

The description of the "transformer" seems a bit muddled, but the ..."electronic gas-tube power supply"... almost certainly indicates that it is NOT a conventional iron-core neon sign transformer, and is probably useless for your purpose.

Can you correct the photo links so it's possible to verify what you purchased, and what your alternate transformer is?

However, I think you need to start looking for a "real" NST, preferably a 12/30 or 15/30. These are readily available, and relatively inexpensive. A 60ma transformer would provide even better performance, but are harder to find.

Find a local neon sign shop, and inquire about old "used" non-GFI transformers. Usually, they can be obtained at low cost, or even for free if you explain that it is for a science project.

Regards,
Herr Zapp

StevenCaton

Sat May 23 2009, 05:53PM

Registered Member #1845 Joined: Fri Dec 05 2008, 05:38AM
Location: California
Posts: 211

Your old transformer may work, but the "secondary ground fault protection" worries me. Did you ever try drawing an arc from it?

If I were you I would buy the transformer from ebay. If, for whatever reason, you don't finish the TC in time, then you can just lash up a Jacobs Ladder really quick. I know you are dead set on building the coil (and everyone wants you to), but JUST IN CASE you can't, then a jacobs ladder could be built.

That transformer might take 10 days to get to your house, so I would make sure that your coil is pretty much ready to go by then, but just without a transformer.
A 12Kv 30ma is a good size transformer so if you decide on that you should make your secondary coil bigger. Maybe 4 inches by 20, or maybe longer.

I built my first coil with a 12Kv 30ma transformer, and the first time I plugged it in, it worked! (ok fine that was a lie, the second time, due to arcing somewhere) Definitely exciting stuff. Deep fried neon was my major reference for my first build.

Find a local neon sign shop, and inquire about old "used" non-GFI transformers. Usually, they can be obtained at low cost, or even for free if you explain that it is for a science project.

I would give that a try, since you are on a slight time and budget constraint, but If they don't have anything, order that transformer quick!

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