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Re: [TCML] 42" Sparks 12/30 - John Freau

Very nice... First thing to catch my eye was the knife switch. I want to
put one for NST power and one for Rotary Gap power on a control box. So I
could prestart gap before before power. On control box... EMI? is there
anything for protecting the wires from box to coil? From arcs(When I reach
those arc sizes)? Nothing special yet. Maybe a sstc play music in far
future. But my thoughts about interference and controlling servos/motor

That's first pic of unpotted NST I've seen. I appreciate that... I have 2
half working 15/30s' I was wondering what I'd be getting myself into.

Tapping with a needle? And I was worried if I was choking my energy input
with wiring lol...

I saw the cap on the sync motor. Is that for starting the motor? Or is that
for PFC? I bought a midget tabletop grinder(1800 rpm) I haven't opened it
up yet...

Another quick question... I am piecing together 20 - in series mmc. 40kv,
.0075uf. I have 25 caps altogether so 5 spares... 40kv and 20 caps seemed a
nice rounded number for future matching plates. I might upgrade to 12/60 or
15/30. Is there a better arraignment possible I am not seeing? Especially
for future use and running more caps either series or parallel? 7.5nf
seemed to be a middle ground... slightly larger than a matching 6nf and
smaller than ltr for 12/30. But it larger than ltr for a 15/30. Thoughts?

Sorry for all the questions. I promise I've done my googling. Sometimes
though I wind up with more questions than solid answers or experienced

Here are some photos of the TT-42 tesla coil.  I gave
the specs in a recent previous email.  You can see
the unpotted 12/30 NST, and the sync rotary gap, etc.


And as Gary mentioned, it's true that it's difficult to tap
PVC insulated solid 12awg wire.  On the old research coil
which used 12awg PVC insulated stranded wire, I used
a needle stuck into the wire as a tap point.


-----Original Message-----
From: Futuret via Tesla <tesla@xxxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Wed, Mar 1, 2017 8:20 pm
Subject: Re: [TCML] 42" Sparks 12/30 - John Freau

Also, the reason the research coil needed 33 turns on the primary
is because it had a large high inductance secondary with about
1500 turns, and at times I used a larger toroid.  It needed 33(?) turns
to tune.  But for the newer TT-42 coil, since it has a smaller
secondary with fewer turns, and lower inductance, and also
the larger capacitor, then it needed much fewer primary turns.

I assume you're familiar with Bart Anderson's Tesla coil
program, " JavaTC"?  It's excellent for determining how many
turns are needed for the tap point with a certain number of
secondary turns, secondary size, toroid size, capacitor size,


-----Original Message-----
From: Futuret via Tesla <tesla@xxxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Wed, Mar 1, 2017 7:53 pm
Subject: Re: [TCML] 42" Sparks 12/30 - John Freau

I looked over those specs.  I had forgotten about that earlier version of
the TT-42 coil.  The specs you gave were of my old "research coil".  I had
forgotten about the 6" diameter secondary and the 34 turns on the primary,
but yes that was the research coil.  Then I decided to make a more
compact coil that I called the TT-42.  TT stands for Table Top.  This
newer coil is smaller and uses a 4.2"diameter secondary with 19" winding
length of 28awg heavy formvar magnet wire (about 1300 turns I think).
The primary is tapped at 13.5 turns, and uses 12awg solid pvc insulated
telephone ground wire (gray).  This was very tricky to wind.  It's a flat
pancake primary.  The inner diameter of the primary winding is 6.5". It's
close wound.  I use a 1.5" x 6" toroid directly above the secondary, and
a 4" x 13" toroid above that, and the 120 bps sync rotary gap.  Such
rotaries have to be phased in by either rotating the motor in it's cradle,
or using an electronic phase shifter.  The tank cap is 0.015uF.

Of course you can build the design that you mentioned.  Either way
will work, there's a lot of flexibility for these projects.  It's better to
use the larger tank cap because it keeps the voltage lower.  I'm surprised
the research coil worked as well as it did considering the small cap value.

This is all I have at my website at the moment, mostly VTTC stuff.
I can't find the photos of my TT-42 coil.  I'll take new photos and
put them at the website.  You can find my sync gap and phase shifter
circuit at this website.



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