Some New Ideas For The SSTC Guys Discussion
Edited/Updated: October 24, 2004
First Post
Subject: some new ideas for the SSTC guys. Date: Sun, 03 Oct 2004 23:02:15 -0600
Original poster: "Dr. Resonance"
Problem --- Exploding IGBT's when they are hit with a sec - pri spark (Terry
Blake's coil terrible demise at our Teslathon).
A few years ago I did some experiments with a flat spiral coil (18 dia. sec.).
In the classic configuration with a .05 uF cap, RSG, and 4.5 turn primary the
sec sprayed out 8 ft long sparks.
At the urging of a plasma physics guru from UW-Madison (Paul Nonn for those of
you who might remember meeting him at Ed's recent Teslathon), I removed the sec
coil and placed it on a stand 10 feet away. I used a 7 inch corona
ball on the bottom to prevent any corona and used a single tap which I attached
to the "normal" primary coil. With some re-tuning it was again spraying
out 8 ft sparks.
What I'm getting at here, is, the SSTC experimenters, Dan M., Steve W., etc,
might try using a larger dia sec coil and then use a 15-20 turn test primary
coil while feeding the sec coil a few feet away. If this works, then the
greatest danger to SSTCing, ie, blowing the IGBT's should become a problem of the
past.
It will take some experimenting --- perhaps the best tap is "inside" the normal
classic tap location or perhaps it will be "outside", but either way, getting
the sec away from the primary to act as a series fed setup should eliminate the
IGBT explosion problem. If it does work the primary can be either a flat
spiral or normal solenoid coil --- perhaps enclosed in clear acrylic with a
large "feeder" wire over to the sec coil.
If someone DRSSTC tinkering wants to experiment with this idea on their present
or planned near future coil, please advise and I will send you a nice 10 ft long
chunk of #6 AWG for experiments --- with 125 kV BIL insulation --- it's 1 inch
thick and offers great HV feedwire performance. We use this "big Red" on
all our HV power supplies to feed the 14.4 kV HV over to the base of the
oscillator. Might work, might not, but worth trying. Dr. Resonance.
Date : Mon, 04 Oct 2004 07:47:39 -0600. Subject : RE: some new ideas for the SSTC guys
Original poster: "Steve Conner"
>I removed the sec coil and placed it on a stand 10 feet away. I used a 7 inch corona ball on the bottom to prevent
>any corona and used a single tap which I attached to the "normal" primary coil. With some re-tuning it was again
>spraying out 8 ft sparks.
So you mean a kind of cross between an Oudin coil and a magnifier? I don't see
any theoretical problem with it, but in practice, the problem is that the
secondary coil is now connected straight to the primary, which means that the
output arcs now pack a punch of 600V DC at several amps.
Richie Burnett invented a slightly different variation on this, that base-feeds
the secondary through an L-match network. In this hook-up, the tank cap connects
from the base of the secondary to one end of the inverter,
and the other end of the inverter connects to the secondary base through a
matching inductor. Steve C.
Date : Mon, 04 Oct 2004 13:09:53 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: "boris petkovic"
--- Tesla list
<tesla@pupman.com> wrote:
> Original poster: "Dr. Resonance"
>
> Problem --- Exploding IGBT's when they are hit with a sec - pri spark (Terry
Blake's coil terrible demise at our >Teslathon).
>
Use magnifier configuration (3 coils in topological sense). Problem
solved. My 2 cents, Boris.
Date : Mon, 04 Oct 2004 19:07:32 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: "Charles Pike"
<ctpike@rcn.com>
Couldn't a coupling capacitor be used between the primary and secondary to
eliminate the DC? Charlie.
Date : Mon, 04 Oct 2004 19:26:19 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: Terry Fritz
<teslalist@twfpowerelectronics.com>
Hi DC,
High coupling is not required if the primary and such losses are low. If there
are nil losses, there is only one place for the power to go ;-)) Even 0.03 CCs
work in many cases!!
>What I'm getting at here, is, the SSTC experimenters, Dan M., Steve W., etc, might try using a larger dia sec coil and
>then use a 15-20 turn test primary coil while feeding the sec coil a few feet away. If this works, then the greatest
>danger to SSTCing, ie, blowing the IGBTs should become a problem of the past.
My failed model was also trying to reduce coupling to "isolate the primary
circuits from bad secondary effects. Modeling always tended to show that a few
amp streamer hits would not hurt much on a conventional coil. Even the OLTC was
pretty well protected with a few transorbs. Dan's book shows that a ground
strike can greatly increase IGBT current which certainly is a factor to be dealt
with!!
>It will take some experimenting --- perhaps the best tap is "inside" the normal classic tap location or perhaps it will
>be "outside", but either way, getting the sec away from the primary to act as a series fed setup should eliminate the
>IGBT explosion problem. If it does work the primary can be either a flat spiral or normal solenoid coil --- perhaps
>enclosed in clear acrylic with a large "feeder" wire over to the sec coil.
I think they should reduce the coupling a bit and go with a flat spiral. But
what do "I" know :o))
>If someone DRSSTC tinkering wants to experiment with this idea on their present or planned near future coil, please
>advise and I will send you a nice 10 ft long chunk of #6 AWG for experiments --- with 125 kV BIL insulation --- it's 1
>inch thick and offers great HV feedwire performance. We use this "big Red" on all our HV power supplies to feed
>the 14.4 kV HV over to the base of the oscillator. Might work, might not, but worth trying.
Ya always have to keep trying ;-))). Cheers, Terry.
>Dr. Resonance
Date : Mon, 04 Oct 2004 19:52:59 -0600. Subject : RE: some new ideas for the SSTC guys
Original poster: Terry Fritz
I think DC means there was NO electrical connection to the secondary!! An old
Tesla coil trick for when we want to really confuse everyone!! ;o))
Basically, without a big load, the primary rings for a very long time. The only
"receiver" is the distant secondary coil that does manage to grab a very
significant amount of the power anyway despite being not directly near...
A classic example that giant coupling coefficients are not needed for low loss
coil systems.... I have seen wonderful demonstration videos of this "Richard
Hull" but I don't know of any that can be easily downloaded off the net.
Cheers, Terry.
Date : Mon, 04 Oct 2004 20:09:56 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: "Antonio Carlos M. de Queiroz"
Tesla list wrote:
>
> Original poster: "Dr. Resonance"
> At the urging of a plasma physics guru from UW-Madison (Paul Nonn for those
> of you who might remember meeting him at Ed's recent Teslathon), I removed
> the sec coil and placed it on a stand 10 feet away. I used a 7 inch corona
> ball on the bottom to prevent any corona and used a single tap which I
> attached to the "normal" primary coil. With some re-tuning it was again
> spraying out 8 ft sparks.
If I understand, you are proposing a kind of drsstc without a transformer, but
using a direct connection. Surely works, as works as an alternative to a
normal Tesla coil too. The only problem is that the voltage gain becomes
attached to the number of cycles used in the energy transfer. Not a big problem
in a drsstc, since these systems apparently can use some extra cycles in the
energy transfer without much trouble with heavy losses in a spark gap. On the
other hand,
they need higher voltage gain to compensate for the smaller input voltage.
Antonio Carlos M. de Queiroz.
Date : Tue, 05 Oct 2004 07:38:13 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: "John"
<fireba8104@yahoo.com>
Terry, Your driving me nuts. I was going to test out a small cap and flat
primary on my mini DRSSTC!!! I thought about using a smaller cap after looking
at a thread on 4hv.org. In this thread, one member stated the common rule of
doubling capacitance only increases energy by 2 fold while doubling voltage
increases energy by 4 fold. I figured since a Drsstc rings up, a higher
reactance cap will ring to a higher voltage and thus a higher energy than that
of a system using a capacitance twice as big. The flat primary was only
chosen since it would not have as many insulation
problems as a helical. Also I think it looks alot better. :-). Next time I'll
open my mouth earlier, till than my hat is off to you my good chap. Cheers,
John.
Tesla list
<tesla@pupman.com> wrote:
Original poster: Terry Fritz
Hi DC,
At 08:58 PM 10/3/2004, you wrote:
>
>Problem --- Exploding IGBT's when they are hit with a sec - pri spark (Terry Blake's coil terrible demise at our
>Teslathon). A few years ago I did some experiments with a flat spiral coil (18 dia. sec.). In the classic configuration
>with a .05 uF cap, RSG, and 4.5 turn
primary the sec sprayed out 8 ft long sparks.
>
>At the urging of a plasma physics guru from UW-Madison (Paul Nonn for those of you who might remember meeting
>him at Ed's recent Teslathon), I removed the sec coil and placed it on a stand 10 feet away. I used a 7 inch corona
>ball on the bottom to prevent any corona and used a single tap which I attached to the "normal" primary coil. With
>some re-tuning it was again
spraying out 8 ft sparks.
High coupling is not required if the primary and such losses are low. If there
are nil losses, there is only one place for the power to go ;-)) Even 0.03 CCs
work in many cases!!
>What I'm getting at here, is, the SSTC experimenters, Dan M., Steve W., etc, might try using a larger dia sec coil and
>then use a 15-20 turn test primary coil while feeding the sec coil a few feet away. If this works, then the greatest
>danger to SSTCing, ie, blowing the IGBTs should become a
problem of the past.
My failed model was also trying to reduce coupling to "isolate the primary
circuits from bad secondary effects. Modeling always tended to show that a few
amp streamer hits would not hurt much on a conventional coil. Even the
OLTC was pretty well protected with a few transorbs. Dan's book shows that a
ground strike can greatly increase IGBT current which certainly is a factor to
be dealt with!!
>It will take some experimenting --- perhaps the best tap is "inside" the normal classic tap location or perhaps it will
>be "outside", but either way, getting the sec away from the primary to act as a series fed setup should eliminate the
>IGBT explosion problem. If it does work the primary can be either a flat spiral or normal solenoid coil --- perhaps
>enclosed in clear acrylic with a large "feeder" wire over to the sec coil.
I think they should reduce the coupling a bit and go with a flat spiral. But
what do "I" know :o))
Date : Tue, 05 Oct 2004 23:26:40 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: "Dr. Resonance"
Larger coil diameters and a flat spiral was my "other" idea as well. I think
the series fed sec might be the way to go to prevent IGBT explosions. Dr.
Resonance.
Date : Tue, 05 Oct 2004 23:26:49 -0600. Subject : Re: some new ideas for the SSTC guys
Original poster: "Dr. Resonance"
Yes, it seems to work very well with a "classic coil" so I thought it might work
with a DRSSTC. Dr. Resonance.