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Re: Pri/Sec coiling



Tesla List wrote:
> 
> > Subject: Re: Pri/Sec coiling
> 
> Subscriber: pwac-at-flinet-dot-com Fri Feb  7 23:37:18 1997
> Date: Sun, 26 Jan 1997 22:40:42 +0500
> From: Jeremy Bair <pwac-at-flinet-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Pri/Sec coiling
> 
> Tesla List wrote:
> >
> > Subscriber: Rodney.Davies-at-anu.edu.au Fri Feb  7 00:04:19 1997
> > Date: Wed, 5 Feb 1997 23:30:27 +1100 (EST)
> > From: Rodney Graham Davies <Rodney.Davies-at-anu.edu.au>
> > To: tesla-at-pupman-dot-com
> > Subject: Re: Pri/Sec coiling
> >
> > On Tue, 4 Feb 1997, Tesla List wrote:
> >
> > Hi Robert,
> >
> > > rwstephens: The wind direction on Tesla coils is very definitely critical when
> > > building a tandem coil system with a separate secondary in each of the two
> > > primaries, or the same primary with two secondaries suspended within it.
> > > In this case, given that the primaries are wound the same direction, or you use a
> > > single shared primary, then the secondaries will have to be wound
> > > opposite sense from each other to get a 180 degree phase difference
> > > between the top terminals.  If you do not do this the two coils will
> > > not speak to each other with hot streamers.
> >
> > Hmmm, I was wondering as to how the two coils arced to each other. I
> > figured such that to make them arc, they have to be effectively
> > either partially (at least 90 degrees) or completely out of phase (180) as to
> > setup a large enough potential difference, else, I guess it might make a
> > display kind of interesting if two coils were attempting to arc to each
> > other and were in phase! Hmmm...has anyone done this?
> >
> > > As mentioned by the others, in a classical two coil, or magnifier,
> > > the sense of the coils matters not.
> >
> > Ah! <Click...bzzz, brain kicks in...> I thought I had a problem there,
> > however, both the secondary and primary on my coil are wound in the same
> > direction..
> >
> > Thanks Robert, much appreciated!
> >
> > Cheers!
> >
> > Rod
> 
> Is the coil winding something you guys take for granted? I mean, I am
> getting ready to build my first, and that thought came accross my mind
> many times, I saw pictures apon pictures of coiling, and they went the
> same direction, so I didn't give it any more thought. But I guess we all
> have it clear, they SHOULD wind in the same direction right?

For a simple two-coil Tesla Coil it doesn't matter. Either winding
direction will work just fine. The primary may be in the same or
opposite winding direction as the secondary.

> 
> So the whole deal with magnifier coils is that they are directly
> (inversely) out of phase, so each primary oscillation would cause both
> secondaries to release at separate identical times? (Newbee alert ;).
> 

Not exactly. A magnifier is a special type of 3-coil system which uses a
specially constructed "driver" (usually a tightly-coupled 2-coil step-up
transformer) to generate high-voltage/high frequency power. This is then
applied to the base of a third coil/discharger pair, which is tuned to
resonate with the driver primary circuit, further increasing the
voltage. Most coilers start with standard 2-coil systems, and only after
some time (and dedication!) migrate to magnifiers. 

Two standard Tesla coils can be set up, usually with common current
energizing the two primaries (by connecting them in series). The phasing
is such that the output voltages are out of phase, and the two coils
will then arc to one another. Ed Wingate has a picture of one of these
type coils in operation on the funet site. However, this is NOT a
magnifier - it's two coils in phase opposition. Check out:

   ftp://nic.funet.fi/pub/sci/electrical/tesla/pictures/wingate/

> If anyone here has ever built a tesla coil running off one 12Kv 30ma
> neon, let me know, this will be my first. And possibly make another with
> two 15kv neons ;) if the first is successfull, and I take it I will
> learn a GREAT deal of information upon the completion of the first?
> Isn't that what practice is?
> 

A 12 KV 300 MA transformer will make a nice power source for your first
coil.

> Also, let me know if these prices are cheap for used neons.
> 
> 12KV 30ma  - 20$  (Franceformer)
> 15KV 30ma  - 25$  "            "
> 9KV  60ma  - 20$  "            "
> 

These are reasonable prices, although you might be able to get some of
these for free from neon sign dealers who are deinstalling old signs.
Chances are they'll be scrapping them, and will give them away for free
or for a few bucks. These prices are LOTS better than the new prices!
Try to get 60 MA versions if you can - they're built tougher!

> If they are good, I will order me up allot.
> 
> Also, I need to know if it is definatly a must to remove the transformer
> from the tar and metal caseing, and why people do it? I have heard
> people saying they boiled theirs in desel to get the tar off, and at
> what cost?
> 

No. Only if its defective, and if you can't get cheap/free replacements.
However, taking these apart is an experience you have to try at least
_once_ to appreciate. :^)

> Thanks people! Also (Man I am loaded today!!) if anyone has any "safety"
> notes for neon transformers let me know, things like, power is left in
> the neon after being unplugged, but not discharged, use a light build in
> the series of the power in to prevent the neon from being over worked.
> Etc!
> 

Read the safety FAQ on Chip's site before doing ANYTHING with high
voltage. Neon sign transformers can kill you, and there are lots of
other hazards you need to be aware of before you start construction and
operation. Check out:

   http://bhs.broo.k12.wv.us/homepage/chip/safety.htm

There's no power stored in the neon... however, depending upon the
primary circuit configuration, you CAN store a lethal charge on the tank
caps!


> Thanks again!
> 
> Jeremy Bair

Safe coilin' to you!

-- Bert H --