ISSTCs, magnifiers, etc

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

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.