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Another capacitive transformer TC
Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
I have tried the mini-coil in capacitive transformer mode and it works:
corona/streamers are clearly visible around the terminal -especially in
subdued light- and 1/2" sparks can be drawn from.
For and induction ring I used an 8" diameter disc with 2" centre hole on
plastic insulators 2 5/16" high; the hole is fitted with a spark-guard a wrap
of stiff 20 mil plastic sheet prevent the mild arcing to L2 experienced in
L2 also given second coat of epoxy varnish to diminish the likelyhood of a
and since the spark-guard was added, so far there have been no problems.
I have noticed that when the ring is grounded corona activity at the terminal
increases- is this because the influence plane has been enlarged or simply that
the effect of grounding the ring is simply to turn the TC from a capacitive
transformer into a directly-coupled transformerless TC with better efficiency?
For greater output, I have tried changing C1 from a 255pF saltwater gel cap to
a much larger 3nf capacitor (a 2 litre pop-bottle SWC)for greater output -so
far without success as there was then much less output at the terminal -despite
the greater energy stored in C1.
Is the observed poor performance with larger values of C1 likely to be due to
poor coupling (as calculation suggests value of C2 should be proportionally
increased) or is there another effect so far not examined -only I have tried
increasing the terminal capacitance with small toroids with little or no
observed effect. Might the induction ring also have to be enlarged?