RE: SSTC Magnifiers / High Frequency - High Voltage transformers

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Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>


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This work of adding a "driver transformer" (my nomenclature) was
undertaken by Duane Byland in the early 1990's.  It worked fine and
performance tended to improve based on increase in Ns/Np turns ratio
with input power held constant.  This was the closest approximation to
a solid-state magnifier that has been widely demonstrated and repeated.

The problem with this approach is finding suitable ferrites, bobbins, wire,
impregnation materials, etc. etc.  Bottom line is 80-90% of us do not
have the "in house" capabilities to build a transformer capable  of
withstanding >1-2kV pk to pk.  Yes you could oil immerse, but that
adds another level of complexity.

 >>>>>>>>Actually, it is not as difficult as it seems.  Soft ferrite cores
are readily available in a variety of
sizes from various manufacturers including ferroxcube, fair-rite, etc...

With a large core, voltage stand-off isn't really a problem.  Basically
U-Cores work extremely well and with using
a ferrite such as 3C90, 3C91, etc..., efficiency and operation at high
frequencies (100-300kHz) is good.
For higher powers, cooling is required as the cores can get fairly hot.

My current design utilizes a Ferrox U-Core using 3C91 ferrite core with
primary at 30 turns, and secondary at 150 turns
for a 1:5 step-up transformer design.

Dan