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Old and new Tesla coil (help!)

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Patric

Thu Jun 03 2010, 06:27PM

Registered Member #2899 Joined: Wed Jun 02 2010, 06:31PM
Location: Deinze, Belgium
Posts: 255

This is my first:http://www.youtube.com/watch?v=4VO9RSRpsTs]

This will be my second, a bit smaller: Oat4zm

I only have to calculate the primary coil, and for that I need a little help. The secondary is 11 cm diameter, 55 cm tall, and has 675 windings 0.8mm. The top-load is a sphere diameter 25 cm.
I have a neon transformer from 5 kV, 30 mA, and a capacitor of 15 nF. The number of windings for the primary I have calculated is +/- 5, but I am not very sure (inches...cm...)
Does anybody knows a descent and simple metric program to recalculate my primary?
Here in Belgium is not much to find about Tesla's...! sad
Many greetings!

803

Thu Jun 03 2010, 07:02PM

Registered Member #2807 Joined: Fri Apr 16 2010, 08:10PM
Location:
Posts: 191

Hi you know me ! I'm tube Guy from the idea biz forum. well my favorite program is tesla map, but that costs money. So the best one you can get is JAVATC. type that into google and you will find the site

Paul

Patric

Thu Jun 03 2010, 08:19PM

Registered Member #2899 Joined: Wed Jun 02 2010, 06:31PM
Location: Deinze, Belgium
Posts: 255

Hello Tubeguy! It is very quiet at theidea.bz, and then I found this place...
I tried JavaTC, and now I have some answers. Next week I will make my primary coil, and I will report!
I have another question, especialy for you!

I have a PL105, a thyratron, mercury vapour tetrode. Is it possible to make a "Vacuum Tube" Tesla Coil with that?

803

Thu Jun 03 2010, 08:54PM

Registered Member #2807 Joined: Fri Apr 16 2010, 08:10PM
Location:
Posts: 191

Not realy, you will not have verry good results with a thytron. I sugest you use a 803 tube, which is advaible at ebay right now at $9 + shipping ( THIS IS NOT MY EBAY ACUTION!) Here is a wonderful tube data sheet web site wich i always use

Good luck

Paul

( what happened to the idea biz, no one uses it anymore):-((

Proud Mary

Thu Jun 03 2010, 10:58PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Patric wrote ...

I have a PL105, a thyratron, mercury vapour tetrode. Is it possible to make a "Vacuum Tube" Tesla Coil with that?

Mercury thyratrons were intended for use as rectifiers and motor speed controllers, and are very slow as thyratrons go.

From the data sheet we see that the ionisation time is 10 us, and the deionization time 1000 us - a whole millisecond - so unsurprisingly it is unsuitable for use above 150 Hz.

Thyratrons come into their own with the ultra-fast hydrogen thyratron, where high voltage high power switching is accomplished at speeds still difficult to equal with solid state devices. Large, costly, hydrogen thyratrons are still used in nuclear physics applications, megawatt radars, and similar applications.

A hydrogen thyratron of suitable size would give a TC a brilliant run for its money compared with a clapped-out old wartime RF tetrode, but you would have to design your own pulse-forming lines, and thoroughly understand gas switch technology to get the best out of them. There would be no circuit to copy, so you'd be in the position of having to do some real experiments, a rare thing nowadays.

You could do some very interesting experiments with your PL105, but its sleepy rise-time isn't suitable for the shock excitation of RF tuned circuits.

803

Fri Jun 04 2010, 12:20AM

Registered Member #2807 Joined: Fri Apr 16 2010, 08:10PM
Location:
Posts: 191

I have a nos 803 and it works great! Also it isn't a tetrode it's a pentode. I have taked to ham that have used tubes all their lives science the 40s and they say they got up to 12 inches from" a worn out " 803

Link to prove my claim. THAT MEANS YOU HERR ZAPP

Herr Zapp

Fri Jun 04 2010, 04:30AM

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

803 -

12 inches out of a "worn out" 803?

12 inches of what? Brown shoelaces? Fish sauce?

Research some well-tuned VTTCs, and see what the typical ratio of input power to speark length is, then compare these numbers to the 803 ratings.

Herr Zapp

wylie

Fri Jun 04 2010, 08:04AM

Registered Member #882 Joined: Sat Jul 07 2007, 04:32AM
Location:
Posts: 103

From the data sheet we see that the ionisation time is 10 us, and the deionization time 1000 us - a whole millisecond

What's with people not using the next OOM unit?

"10,000 mili-units"

"so, 10 units?"

Is it just marketing?

"This 50milifarad capacitor is our best product yet."

"Fifty Thousand Microfarad, you mean?"

"ummm, ok, i quit. *door slam* "

Steve Conner

Fri Jun 04 2010, 10:30AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Millifarads aren't used for some reason. I don't know why. Many old American schematics used "mF" for microfarad, so maybe that's why, to avoid confusion.

And there were other Americanisms like micromicrofarads (spelled mmf or ÂµÂµf at random) instead of pF, and a strange allergy to nanofarads.

For all of the other electrical units there's no reason not to use the proper SI orders of magnitude. We've always used them on electrical schematics in Europe.

I know of two hydrogen thyratron-powered Tesla coils, built by Richard Hull and Thomas Rapp. But mercury vapour thyratrons are too slow.

Maybe someone did once get a 12" spark out of an 803. Tubes can be abused far beyond their published ratings. It shortens the life drastically, but hobbyists usually get bored after a few hours of runtime, so you'd never know. You said "worn out", maybe it was brand new before it made the 12" spark, and worn out afterwards.

Proud Mary

Fri Jun 04 2010, 02:34PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

wylie wrote ...

From the data sheet we see that the ionisation time is 10 us, and the deionization time 1000 us - a whole millisecond

What's with people not using the next OOM unit?

"10,000 mili-units"

"so, 10 units?"

Is it just marketing?

It's plain old antiquity in the PL105 data sheet case - 1954 - when Elvis cut his first ever demo disc in Nashville, Robert Oppenheimer was accused of being a Communist, France agreed to partition of North and South Vietnam, an 8lb meteorite (not a 3.63kg one

) struck one Liz Hodges of Sylacauga, Alabama, (claimed to be the first recorded instance of a meteorite striking a woman), and a British Medical Committee report became first to propose a link between smoking and lung cancer.

Steve makes some good points, to which I'll add that terms used in industry often reflect the customary usage of many years, held in place by cultural inertia.
A good example is the persistence of avoirdupois weight in the face of heavy-handed governmental attempts to abolish pounds and ounces in favour of kilogrammes. A market trader was even sent to prison for continuing to sell fruit and veg in avoirdupois weights, an event of such absurdist brutality that the government back-peddled and sanctioned the use of avoirdupois weights side by side with the metric system.

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