Hi Chris,
That is a nice looking breadboard. It looks like after you get everything sorted out you can mount everything except that big variac in a fairly compact unit.
My 833A VTTC consist of two levels: a 60 Hz deck and a RF deck. Construction is open. I prefer the functional look where everything is visible and open but construction is clean and orderly. The open construction also eases modification and offers good cooling.
The lower deck is all 60 Hz stuff. Everything on this deck is mounted on an aluminum plate measuring 24" x 14" x 0.5". The aluminum plate provides good rigidity, good heat sinking, a good ground, and also serves somewhat as a counterpoise for the secondary coil above it. The lower deck contains the following:
* MOT
* Voltage doubler (MOT capacitors, diode, and RF bypass capacitor)
* Filament transformer
* Interrupter transformer
* Interrupter triac
* 2 fans
* EMI power line filter brick
The upper deck is all RF. Everything is mounted on a bakelite plate measuring about 18" x 10" x 0.5". The upper deck contains the following:
* 833A and RF bypass capacitor
* Tube protection low pass filter (resistor with coil around it connected to plate)
* Fan for 833A
* Primary coil with 9 tap points
* Primary capacitor
* Adjustable height feedback coil currently about 2 inches above primary coil
* Grid feedback components (capacitor and resistor)
* Secondary coil
There is also a front panel attached to the lower deck which contains:
* MOT variac
* Filament transformer variac
* MOT voltmeter
* MOT amp meter
* Filament transformer variac
* Filament volt meter
* Switches
* Pilot lamps
* Interrupter circuit board and controls
Total height is about 30 inches. It weighs about 50 pounds. I wanted a portable unit so that I can take it to schools and other places for demonstrations.
----- Original Message -----
From: "Chris Reeland" <chrisreeland@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, March 19, 2018 10:58:32 PM
Subject: Re: [TCML] VTTC MOT question
Hi Steve,
I thought I would post a picture of my rig taking up the bench if your
curious.
https://photos.app.goo.gl/2JucJp5k0DIsiSfl2
I have not done too much this weekend on it like I thought, been thinking
on it alot, and have also gotten distracted by some other fun stuff at
times. I am also considering some bigger changes also. Need to think a bit
on this.
Anyway the big roller inductor on the left is a temporary tuning aid that I
am using. My Dad found this at a past Hamfest that we were at, oh maybe 2
years ago. Only just recently started using it. It has up to about 100uH.
Way more than enough. Pretty handy for testing tuning changes. Easier to
see "where" you are at. Easy to change this quickly while running of course
to verify.
Currently at about 5 turns. The goal is not to use any turns at all. Can
also see if you over cap some, because you will try to keep turning it down
hitting the end stop. Even though it gets you fine tuned in to current
components for max spark length, it is wasted energy there. Have the 29"
here. That is one of the things why I said I think there is still some
more. It does have an advantage of not changing, as John says of the
primary coupling turns to the secondary and affecting its feedback winding
coupling. Can have too many things interact. I usually like also to stay to
fixed primary/feedback also when I figure out one when building it. But the
roller will be temporary.
Even though I have alot of micas, can not get it quite right yet, gets
messy with several parallel, at times parallel and series, and just series.
Type E, F3, G2, G3, G4. Run out of room to mount them, even though I
started with a big mounting board. Too many poor temporary cap connections
also. Had the caps on a stool in front of coil, not much bench space left.
So I put in the closest single cap I have back in for now, a F3. Can never
have enough cap values, especially in a convenient size and voltage. Don't
really want to use several G3 or G4 micas on this coil, definitely
overkill, no room to mount nicely.
So debating the several ways of correcting this currently, so I can keep a
"nice friendly" value and size. Or I need more micas to add to the big
collection. Even, I am now having some space issues.
So I thought I would give some details of were I am at currently. Hope it
makes some sense.
Chris
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