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Re: Terry's DRSSTC - First light ;-))

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi DC,

At 06:50 PM 3/15/2005, you wrote:

I presume you are using some type of grounded strike rail? 

Yes.  I put on a nice new rail "since" I blew the last IGBTs:

http://drsstc.com/~terrell/pictures/StrikeRail.JPG

But ya know how sparks sometimes just don't behave...

http://www.feeta.co.uk/old/10_feeta/public/pictures/lightning/tower-miss.jpeg

The darn streamer might have curled in around under the rail... That is what I "thought" happened. But Erik's face was a few feet away, and he say's it hit the main DRSSTC control box...


We make up 3 stands that terminate on top with a 1/2 dia metal cabinet knob.
The stands have a 5 x 5 inch x 1/4 inch thick base.  Each vertical brass rod
is adjustable from 12 inches up to 3 ft.


I was thinking "barbed wire" might make a better strike rail "coating"...


The three are joined together with standard "bananna" plugs and receptacles
for fast setup.

Might be nice to have the H-bridge on banana jacks for easy replacement.... But best not to blow the dumb thing up in the first place per my other post on protection...


We place them 3-4" away from the edge of the upper base support --- just
outside of the primary.  We made the vertical brass piece adjustable with a
small hose clamp.  This allows vertical adjustment for different coils such
that the small terminal ball is approx 3-4 inches above the primary coil and
3-4" outside of it.  In essence, a portable strike rail!

Would it not be better to have "points" like a lighting rod.... The balls are safer however if you fall onto one...


It's very easy to set up and makes the mounting of a fixed ring on the pri a
thing of the past.  Allows placement around different coils as you build
different designs.

The "box" has a heavy epoxy/plastic coating. The six panels are not well grounded since the screws do not penetrate the coating. I need to mod a mill bit or something to chew through it at the screw holes... If the streamer did hit the box, the electronics may have gotten a "glitch". I "thought" it was out of range... But the electronics were not damaged "permanently" or anything...

It was at Bill Lemieux's house in Denver, so I did not bring along the extra bulk of the video camera to "catch" the event...

Cheers,

        Terry


The main ground is attached to the main ref ground --- same one as the
bottom of the sec coil.


Dr. Resonance


>
> >Could a DC blocking capacitor be added in series with the ground
connection
> >to the tesla coil secondary?  In the event of a strike to the primary the
DC
> >bus caps cannot then discharge through the IGBT into the ground via the
> >secondary.  Just an idea, maybe there is greater problems than this to
worry
> >about or this just adds further problems.
> >
> >Cheers,
> >
> >Paul.
>
>
> I have been thinking real hard on this %:-)
>
> I blew two more IGBTs Sunday when a streamer either hit the primary again
> or the DRSSTCs case at 41 inches!!!  They guy closest said it hit the case
> where others though the primary got hit (no cam this time).  Happily, it
> just blows pairs of IGBTs which is not bad to fix at all!
>
> A DC block all by itself still lets bad RF through, but simply adding an
> inductor forms a bandpass filter that may indeed do the trick!!  I wrote
up
> the details here:
>
> http://drsstc.com/~terrell/notes/DRSSTCprotec.pdf
>
> Thanks for the starting idea!!
>
> Cheers,
>
>          Terry
>
>
>