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[TCML] Greetings once again
Greetings once again from Ken Herrick. I've rejoined the List after a
couple of years--at least for a while, having become burned out so to
speak--both mentally & hardware-wise. Now refreshed, I'm back at trying
to get my late, lamented s.s. coil up & running again. When it ran, it
featured an untuned primary, secondary-coil return-current feedback, and
the hopelessly complex version of my vanity-patented primary circuit.
Now, I'm trying to re-do the whole primary electronics, basing the
design on the original ckt but simpler. I don't know how s.s. is faring
these days on the List; last I checked there wasn't much chit-chat along
that line anymore. However, for any who might be interested, I've
posted a couple of basic diagrams at http://drop.io/pat_ck_dblH.
Dwg DBL-HBR.jpg shows the current paths thru what I call a double
bridge. The central capacitor represents the f.w. rectified mains d.c.
The other two are "flying" capacitors, kept charged thru bifilar chokes,
not shown, from the mains supply. The switching sequence is all-As on
then all-Bs on, etc. You will note that the voltage on all 3 capacitors
in series is applied to the coil, as peak a.c., at the switching
frequency. The peak voltage appearing across the A transistors is twice
a capacitor voltage and across the Bs, 1x that voltage.
Dwg Patent-ck-dbl-H.jpg is the simulation circuit. The basic scheme
works nicely in simulation, and it did work in the prior (too complex)
hardware v. of some years ago. Some may remember the dandy photo I
uploaded at that time. I've put it up on the drop.io site also (Dwg
In the simulation dwg, secondary feedback clipped by D7 & D8 is
amplified to drive the 8 switches that represent power transistors. (My
freebie v. of the simulation app won't allow that qty of "real"
transistors, so I use the sw's.) With the Tesla-coil parameters I
chose, I get 1.9 MV pk appearing at the output 300 us after To. RMS
primary current during that burst-time is 140 A which would yield a
mains current of some 14 A at 10% d.c.
I've built so far, to this scheme, all but the S3/S4/S7/S8 part (which
only occurred to me a day or so ago that I might incorporate). I
currently have trouble with the circuits emulating the U1-E2 part (i.e.
the input circuits) and will have to get that and the output part,
currently less the S3/S4/S7/S8 part, working before I can try to add on
Any comments will be welcome!
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