Re: SSTC idea

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>

Okay, you can theoretically cross the two, but not in the way you mention.

A typical SSTC (which most build) acts in a completely different way than a
conventional spark-gap coil.  Your typical SSTC is basically a switch,
nothing more.  It switches whatever input voltage you through at it at the
resonant frequency of the secondary coil.  There is no primary tank circuit
in the conventional sense.   The output of this switched input voltage is
fed to a turns-independent primary which directly excites the resonant
secondary coil.

On the other hand, in a conventional coil, the NST (just a high voltage 60Hz
source) charges up the tank circuit and a spark gap (switch) discharges the
tank capacitor which is charged by the NST into the primary coil of the
conventional coil causing it to resonate and also exciting the secondary
coil in the process.  (simple and short explanation)

The NST here is the power supply of our conventional coil.  In a typical
SSTC, we are only building a switch.  The power supply for typical SSTCs is
usually 120 or 240VAC line power.

The cross of which you state is basically saying you want a solid state
power source instead of the NST and still use a traditional spark gap.  This
has already been done.  Its basically just using a high voltage switching
power supply (Solid State) usually DC and making this the power source.

However, the more exciting direction to go is to replace the traditional
spark gap with a solid state version.  This would be a definite challenge,
and although there has been a lot of talk regarding this, I have yet to see
one in practice that can switch over 10kV (at least in the amateur world - i
have seen 40-60kV solid state cathode switches in radar transmitters).
Remember the old adage about solid state stuff.  Current is free, but you
pay for voltage.  So a high voltage solid state switch would be very
expensive and difficult.

I believe though, that a lot of the OLTC (Off-line Tesla Coils) use a
similar solid state switching arrangement however it is at low voltage
(<1kV).

The Captain






 > HI all,
 >
 > Thinking about the SSTC design and how they can't do as well as a spark
gap
 > coil.. I wonder if it would be possible to do a cross between the 2
designs.
 > I wound if instead of a NST use the SSTC driver to charge a tank-cap then
 > have the usual sparkgap system. I don't know how to work out the caapcitor
 > value, I would imagine it to be small since the SSTC driver would need to
 > charge it, though im sure somehow the SSTC could charge say a 10nf cap
based
 > on a simple 8/30ma NST design. Perhaps the SSTC would need a small driver
 > coil to boost the 100VDC line input ( or whatever ) to like 10KV. It would
 > bascially be the same as a spark gap coil though instead of damped waves
it
 > will be CW mode with the peek powers avaliable from the tank cap.
 >
 > Has anyone tried such a setup or know if that idea will work ?
 >
 > Cheers,
 > Chris
 >
 >
 >
 >
 >