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direction of sec and pri coils

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doctor electrons

Fri May 21 2010, 09:36PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

I believe that the topology of the coil (tube or solid state) should not matter. However, when current flows through
a conductor, be it a primary or secondary coil, the magnetic field or flux will go in one direction for dc and it will reverse every
cycle with ac. Since in a tesla coil the fields are pretty much parallel to each other i don't think it will matter. You would have to try
both and see which gives a better result. Excellent topic to think about and toy with. Since the field sees the turns as a ring basically,
the direction of the winding should be irrelevant. Only experimenting can answer that one!!

Herr Zapp

Sat May 22 2010, 01:09AM

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

doctor electrons -

803 is building a vacuum-tube coil, which utilizes three windings: primary, secondary, and feedback.

The "topology" of a vacuum tube coil IS quite different from a solid state coil.

Technically, the polarity of the feedback coil's output IS critical, as it must provide a pulse of the correct polarity to the tube's grid to turn the tube off and set the system into oscillation. Practically, you can wind the feedback coil either RH or LH and if the coil doesn't oscillate, reverse the leads.

Regards,
Herr Zapp

StevenCaton

Sat May 22 2010, 01:57AM

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

I would say don't worry about the direction the coils are wound in for a VTTC. Sure, you might have to swap the wires on the grid coil, but thats an easy fix.
I vaguely remeber someone saying the relative winding direction does matter for a vttc primary and secondary, but I don't think that has been thoroughly proven true.

However, ensuring proper phasing is critical for something like a twin system, where there are two coils that create sparks that connect in mid air. (for something like this the secondaries and primaries can be wound the same but the leads to the primaries need to be inverted so the primary currents are 180 degrees out of phase)

So don't worry about it too much.

doctor electrons

Sat May 22 2010, 02:42AM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

Herr Zapp wrote ...

doctor electrons -

803 is building a vacuum-tube coil, which utilizes three windings: primary, secondary, and feedback.

The "topology" of a vacuum tube coil IS quite different from a solid state coil.

Technically, the polarity of the feedback coil's output IS critical, as it must provide a pulse of the correct polarity to the tube's grid to turn the tube off and set the system into oscillation. Practically, you can wind the feedback coil either RH or LH and if the coil doesn't oscillate, reverse the leads.

Regards,
Herr Zapp

Zapp, again with your b.s.
First! Never said that the topology was the same. And OBVIOUSLY solid state is much different from tube technology. Thats the first thing that
makes you highly intelligent.
Second! Never said anything about the feedback coil, which is a third coil! I said the words again that may be too big for you.
PRIMARY and SECONDARY!!
LEARN TO READ OR SHUT UP! I am POSITIVE i am not the only person here fed up with your B.S.
PLEASE stop ruining the forum with your arrogance.
Regards, someone not as bored as you.

Proud Mary

Sat May 22 2010, 08:13AM

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

Herr Zapp wrote ...

a pulse of the correct polarity to the tube's grid to turn the tube off and set the system into oscillation.

Gasp!

Steve Conner

Sat May 22 2010, 12:52PM

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

I know a few people who have built pentode VTTCs with a separate screen supply, mostly using the GU-81M tube. They work. It's nothing new or exciting.

The classic plasma tweeter circuit uses screen modulation, so again it's nothing new.

Dr. Electrons, will you give it a rest. Herr Zapp might be pedantic, but he knows more than you about Tesla coils.

Here's the dope: Single resonant (untuned primary) coils will only work with one polarity, they won't oscillate at all if you connect it wrong.

Dual resonant coils (DRSSTC, classic Armstrong VTTC with tuned primary) will probably work both ways round. They have two possible operating frequencies, and changing the phasing usually selects one or the other. The spark output, and tendency to flash over or catch fire, will be different for the two frequencies.

In either case, the solution is to try the feedback coil both ways and use whichever performs best.

doctor electrons

Sat May 22 2010, 01:17PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

Steve!
I will happily give it a rest. As soon as Zapp decides he doesn't have to attack everything i say.
Which was all accurate by the way. I also happen to know enough about tesla coils to reply to the post.
A ct used for feedback is the only coil where the winding direction has bearing on anything, and only
if the currents are dc. Lets do an experiment. Zapp..... 2+2=4. I am already curious as to why you are
going to tell me it doesn't.
Also, For Steve, Thank you!! Your answers and posts are useful and informative!

803

Sat May 22 2010, 03:30PM

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

I never said that a screen supply is new I said that a screen supply for the little used 803 is new. My thought is that a . 803 can produse a 12 inch spark useing the tied grid, right So what I thought is that will using a screen supply improve that figure?
2. Please don't argue, I don't want it to be locked.

Have a nice day,8-)

Paul (sorry if I sound grumpy, am a little anoyed with some other members)

Mads Barnkob

Sat May 22 2010, 03:58PM

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

803 wrote ...

I never said that a screen supply is new I said that a screen supply for the little used 803 is new. My thought is that a . 803 can produse a 12 inch spark useing the tied grid, right So what I thought is that will using a screen supply improve that figure?
2. Please don't argue, I don't want it to be locked.

Have a nice day,8-)

Paul (sorry if I sound grumpy, am a little anoyed with some other members)

12 inch sparks from a tube with 125 Watt plate dissipation is by my experience a very high goal, a screen supply/driver would only control the screen grid, if in phase with the control grid, give the same output as if it was a triode.

I fought a lot with my dual 811A VTTC to get 33 cm sparks when they are overdriven at 3500V, from there an up I experienced fast red plates or flash overs in the tubesocket between leads from the socket up inside the tube itself.

Do not be too annoyed with us, we are just as stubborn as you are :)

803

Sat May 22 2010, 05:11PM

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

Sorry I meant 2 803. And the 803 is highly underrated, hams have given a single 803 1kwatt input at 11kv peak and it doesn't heat up! Thatâ€™s because it is always hard off or on because of its low resistance and design

This is the forum, I am vacuum tubes tesla coil:-D

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