Re: ISSTCs, magnifiers, etc

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

Original poster: humanb-at-chaoticuniverse-dot-com 

Steve, vary interesting. What is your reasoning behind "primary" current 
feed-back? Do you think it will overcome some of the issues with other 
feed-back methods for magnifiers? But what really caught my eye was your 
self-resonant mode driver with audio modulation. How has this worked? I 
think audio modulation in self-resonant mode should be able to produce some 
good quality audio. One of the problems with the Plasmasonic has to due 
with frequency adjustment. It becomes detuned from the plasma discharge and 
any object that comes near the secondary causing audio distortion. How is 
the quality on yours? What I also like is the idea of having a single board 
that could do both huge sparks in double resonant interrupted mode and with 
just a few jumper settings do audio modulation (non-double resonant mode, 
of course). Ideas?

Thanks,

David trimmell


On Wed, 21 Jul 2004 07:21:03 -0600
  "Tesla list" <tesla-at-pupman-dot-com> wrote:
>Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> >Steve has 
>anyone yet figured out how to "self-resonate" a ISSTC magnifier?
>My plan (and I don't know if it will work) is to use primary current
>feedback, with a PLL driver whose frequency control range is limited to
>force it to lock on to the correct mode.
>I've already got this primary feedback/PLL driver circuit working with a
>2-coil ISSTC made from the primary, tank cap, and secondary of my Tesla-2
>spark gap coil. It drives the system at its lower pole (~210kHz) and
>produces 23" arcs at 3 breaks per second with 300V DC supply, limited by my
>pathetic 150mA power supply. (Not to mention the ceiling, as the setup is
>sitting on quite a high table.) I hope to plug it into rectified 240V line
>and test it up to 400 bps this Saturday.
>
>Interestingly, Antonio's new sstcd calculator seems to say that this coil
>can't work, even though it was Antonio's idea to build it in the first place
>:)) I clocked the peak primary current at roughly 120A, with a 300V DC
>supply, and if I type this figure into sstcd, it says I need something like
>a 200pF tank capacitor and a coupling of 0.009? In fact, I have a 12.5nF
>tank and k=roughly 0.1.
>I think this is because the coil doesn't work in anything like quasi-CW
>mode. It rings up slowly, then when it breaks out, the discharge sucks the
>power much faster than the inverter can supply it, and the primary current
>plummets to 40A (peak). So it is obviously pretty badly mismatched. Yet it
>still seems to give bigger arcs than it did as a SGTC.
>An earlier picture (doing 16" arcs at 3bps, with secondary base current
>feedback, and probably poor tuning)
>http://scopeboy-dot-com/tesla/dw-isstc/drsstc_yay.jpg
>Some information (will be updated later)
>http://scopeboy-dot-com/tesla/dw-isstc/dw-ipix.html
>Steve C.