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Basic idea question

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EvilTesla-RG

Fri Sept 04 2009, 09:17PM

Registered Member #1523 Joined: Sat Jun 07 2008, 02:05PM
Location:
Posts: 97

I will soon begin work on my third (Spark Gap) Tesla Coil.

This one is special, I am building it for a chemistry profesor, and I'll be building it with two other students. (niether of whom have built a Tesla Coil before)

I have no idea what my chemistry profesor wants with a Tesla Coil, but hey, I get to build a Tesla Coil for free!

Anyway, so my idea. I am thinking of using a Sychronis Rotery spark gap.

(My last two coils were static spark gaps)

What I am thinking, of course the motor for the gap will run off of line current, and so be parrellel to the NST (Or whatever I wind up using).

So of course, this means that some amperage will be diverted to the motor, and some to the NST.

What I was thinking, was that it may be possible that really "more" amperage may wind up going to the motor than I need, so maby I should put a variable resistor in series with the Gaps' motor?

This will increase resistence of the motor, directing more energy to the NST, thus longer sparks. (and of course, it would slow down the motor, so a ballance would have to be reached)

Of course, this means that the total reisitence increases, thus decreasing the total amperage. Would this than decrease the amperage through the NST enough to cancel out the point of having a variable resister in the first place?

And more so, lets say I can't get ahold of a Sychronis motor, would the results differ drasticly between a sychronis or Asychronis motor?

(since I know the point of an Asychrnois motor is to spin fast enough that whenever the spark should fire, it is ready to fire)

Hazmatt_(The Underdog)

Fri Sept 04 2009, 10:13PM

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

Even though your motor and NST are on the same circuit, they pull their own current due to their loads. The motor will pull current depending on how much rotary load it has to turn, your spark gap disk. And the NST will pull its short circuited current continuously up until its saturated.
So No, doesn't work that way.

If you want to put a resistor inline, you can, but its probably just going to catch fire, considering you're pulling probably 6A for the NST and 8 to 10A for the motor.

You probably won't find a suitable synchronous motor. I haven't really seen them around for 1800 rpm unless its for some 220 or 240 50Hz application.
That's why people grind flats in their rotors on 1750rpm motors.

The beauty of a synchronous motor is that when the system is perfectly in tune, you never misfire, promoting streamer growth. Async. allows you to increase break rates and use smaller capacitors so you can deliver more pulses per second, and more overall average power. It shortens the streamer length compared to synchronous, but it also looks more smooth and continuous in comparison, and if you have a kw or more, it doesn't really matter that the faster break rate is shortening your streamer length a little, you have plenty of power anyway.

If I were you, I wouldn't bother with a rotary. I have built several, and my last one is wonderful.. with the exception that it does misfire because its asynchronous. But it took 3 weeks of work which could have been spent on other things.

I think instead you should be building a vacuum sucker gap .. Richard Qucik gap.. because that will allow finer tuning then the rotary with I think better results. PLUS.. its economical and labor conservative in comparison to the rotary.

Plasma Lover

Fri Sept 04 2009, 11:03PM

Registered Member #1911 Joined: Mon Jan 05 2009, 06:30PM
Location: Salem, Oregon, USA
Posts: 165

Unless you are absolutely set on building an RSG, I advise building a hyperbaric gap, since they have great quenching and tend to be fairly minimalistic in part, time and monetary requirements.

Sulaiman

Sat Sept 05 2009, 02:59AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Not only will the rotary gap eat up time and money,
if left to others maintenance may become an issue.
Spinning masses may also pose more of a safety risk than the TC itself.

I think it would be a good idea to find out what your chem teacher has in mind
as it may affect the design.
e.g. Is it to produce ozone, or maybe show the colours of various vaporised ionized chemicals, determine insulation properties, use the high temperature arc, etc. etc.

EvilTesla-RG

Sat Sept 05 2009, 03:41AM

Registered Member #1523 Joined: Sat Jun 07 2008, 02:05PM
Location:
Posts: 97

lol, I did talk to my chemistry profestor, and for him, as long as it fits on a table top it is good.

I'll drop the resistor idea.

So the little extra performance from a rotary gap really isn't worth the extra effort?

How much better DOES a rotary preform than a static?

I am aware of RQ gaps. (That is what I would do if I go static)

But I can't find any information on this Hyperbaric spark gap you speak of.

where could I read about these?

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