SISG PC BOARDS

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>


Followers of the SISG Thread:

A few weeks ago I contacted Terry and offered my coil as a full scale
test unit for the SISG concept.  My coil is MOT powered with a full
bridge rectifier and filter caps to provide a DC based system.  I then
use DC resonant charging to charge up a 38 nF Tank Cap and fire a 4.5"
dia X 21" coil with a 5" X 16" (John Freu) Toroid and a 460 BPS RSG.  It
was clear from the outset that this medium power application would
require generous heat sinking of the IGBT's.  Since my primary operating
voltage is ~ 17 kV I would require ~ 20 of the SISG circuits to replace
my rotary spark gap.  Recall that each SISG circuit is set at 900 volts.

I consulted with Terry and designed a PC board that contains (4) SISG
circuits.  Thus I would need (5) boards in series for my application.
Last week I ordered these boards and some extras.  I also made a bulk
order for the 800 amp IGBT's from Singapore.  I ordered in bulk to get a
lower average cost in the hoeps that TCML members would want to purchase
the excess.

The board is 2" X 7.75" and the layout can be viewed at:

http://teslaboys.com/SISG

The boards have power traces on both top and bottom with 3 OZ copper in
order to provide a high current rating.

The heat sinks are quite large and give a 20 Deg C rise at 4 watts
dissipation and 200 FPM air veocity - 38 Deg C rise at 8 watts and 400
FPM - 42 Deg C rise at 12 watts and 600 FPM.

We will need these special features to reach 460 BPS.

The boards are designed to be set side by side with every other one
reversed so that terminations are easy at each end of the boards.  A
crude layout is available at the link above.  Each board would be rated
at 3600 volts.  I put a via between each circuit so that if one needed
to increment in less than multiples of (4) circuits it could be done.

The boards will be done in a couple of weeks.  I do not have a confirmed
ship date on the delivery on the IGBT's.

If you would like to try these boards out let me know off list at my
home e-mail teslamark@xxxxxxxxxxxxxx  Remember, this concept is not yet
tested in fullscale yet.  I hope to be able to offer a board and the (4)
800 Amp IGBT's for $60(Note that the IGBT's are $23 in single qty from
Digi-Key - but that price is a joke).  The rest of the board components
are readily available from the typical distributors at reasonable cost.

I have not provided all the technical details here for review but am
working on that and will let you know when and where that is available.

Thanks.

Mark Dunn