Re: Small VTTC's

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Shad Henderson <shenderson@xxxxxxxxxxxxxxxx>

Hi All,  Dan,

In my experience, the "smallest" VTTC I could build that still produced
a (tiny) brush discharge was a bipolar setup:


1" thinwall PVC wound with 36ga wire, 6" long
Primary wound with 18ga "zip cord", ?? turns (don't remember)
Tank capacitor was 2 air-variable caps in parallel.  Not sure of the
value, just cranked 'em to 1/2 value and removed primary turns to tune
via a 'scope.
Toploads were the 1/4" brass balls found in the lamp section of Home
Depot. A wire came from each end up and towards the center above the
secondary for the sparks to form.
The tube was a 6SN7 twin triode, both sections in parallel.
Power supply was a small transformer that put out 360V DC at maybe
30-40mA and provided filament power.  It was being abused in this role.
Grid winding of 16-18 turns of 20ga (easier to handle than 36ga), grid
leak C and R sized by trial and error.

It never produced *big* sparks, only just over 1/8" between the two
wires.

It was *very* touchy about tuning, and didn't like to be "approached" by
your hand.  Didn't light up neon or florescent well though.  Being a
bipolar coil, it didn't generate lots of rf hash like a traditional
single ended coil will.  Aside from being touchy about tuning, it was
extremely stable, and didn't beat up the little transformer *too* badly.
However it did drive the 2 dogs completely crazy when it was running, so
it was probably screeching away in that audio range just above what
humans can hear. :)

Nice thing is that it all fit in/on one of those radio shack project
boxes.  Somewhere I have a few photos of the lashed-up prototype before
I got it working well.  Have to dig that up.

Just my $.02

Shad H.



On Fri, 2007-04-13 at 16:49 -0600, Tesla list wrote:
> Original poster: Dan Williams <coilerdude@xxxxxxxxx>
>
>
> I'm wanting to build a miniature VTTC
>
> Thinking I will use a long pill bottle for the
> secondary
> Wondering if anyone has built a small VTTC and would
> be willing to give up some gem's of info?
>
> I am currently working on a small VTTC using a 3C24
> triode
> The secondary is wound on a spice container.
> The dimmensions are 13" high by 6X6
>
> Pictures will be on my website soon.
>
> My aim is to build the smallest VTTC still capable of
> breakout.
>
> Any pearls of wisdom greatfully appreciated!
>
>
>
> 
____________________________________________________________________________________
> Don't get soaked.  Take a quick peak at the forecast
> with the Yahoo! Search weather shortcut.
> http://tools.search.yahoo.com/shortcuts/#loc_weather
>
>