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Re: S.s. info...re: differing secondaries
Original poster: "Kennan C Herrick by way of Terry Fritz <twftesla-at-uswest-dot-net>" <kcha1-at-juno-dot-com>
I recently reported on problems with a new secondary. Happy to report that
I've rebuilt it as planned: ~570 turns of 22 ga. (not 20, as I'd planned)
in 12" dia. x 36" high, space-wound over 0.003" Teflon, which was in turn
placed over a tight layer of 0.06" dia cotton twine to form a spiral track.
A Sonotube is the basic former.
I've also solved my s.s.-system's phasing problem so as to properly utilize
secondary current as the excitation-determining signal for the primary
circuit. It took the addition of a 2-cent resistor.
Here's a run-down of what now happens:
1. Primary, 2 equivalent turns carrying ~220A of pulse-burst current at
the secondary's Fr, which is ~160 KHz. Even though I am utilizing 85A
power MOSFETs, I drop some 12% of the applied mains-voltage in the MOSFETs.
Ultimately, then...more MOSFETs!
2. Secondary as described. Primary & secondary closely-stacked, coaxial
and of ~ the same diameter.
3. Toroid, 6" x 24" Landgren.
4. With full primary supply-voltage (of ~160V) applied, spark break-out
from the toroid is at ~150 us, with the secondary's E-field rising
exponentially during that time.
4.1 Sparks are up to ~3 ft. in length, fat and branched.
4.2 At break-out, the secondary's E-field diminishes exponentially to ~1/6
of the peak, over ~100 us. Power continues to be applied for ~5.5 ms
during the pulse-burst.
4.3 Measuring the secondary's return-current via a 1 ohm resistor, I find
its envelope is identical to that of the E-field. Current at spark
break-out is ~12A and that during the rest of the pulse-burst is ~2.8A.
I'm rather surprised at the 12A and also wouldn't have expected that the
current would diminish that much during the balance of the pulse-burst.
5. Temporarily reducing the primary's supply voltage, I find that sparks
just break out from the toroid at ~1/2 line voltage. My surmise from that
is that I might reduce the quantity of secondary turns by perhaps 1/3,
still achieve spark break-out, and--by virtue of having reduced the
turns-ratio--perhaps be able to pour even more power into the spark during
the after-breakout period.
I'll appreciate comments...