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60 bps sync operation (new tests)
All,
In my original 60 bps tests, I saw a greater efficiency than at 120 bps.
In recent work I saw lower efficiency, but this was simply due to an
insufficient ballasting range.
Now, in new work, I'm seeing about the same efficiency as at 120 bps.
(sync rotary was used in all tests)
Test 1. 60 bps with .031uF cap, spark reached 42", but needed
590 watts. The sparks are thin, with spikeyness and
flowerettes at the ends. The sparks want to emit from all around
the 13" smooth toroid, but by cleaning the dust off the toroid,
and tuning carefully, I can obtain mostly one streamer. I tried
larger corregated toroids, but extra streamers cannot be suppressed.
But a 26" corregated toroid did a pretty good job of extra streamer
suppression, but spark was reduced to 39" at the above power level.
Power factor is good at near-reso, VA measures 600.
Test 2. 60 bps with .0147 cap, spark reached 42" at only 560 watts
which is similar to the efficiency at 120 bps. I tried only the 13"
smooth toroid, and the sparks emit from only one point. The sparks
appear as normal TC sparks, the flowery spikeyness is gone. Power
factor is still good (600VA), near reso setup. Sparks show good
growth and surging.
Why the differences with .031uF and .0147uF? The bang sizes are
theoretically the same ignoring losses. Possible reasons: The
coupling is probably tighter with the .031uF, the quenching might not
be as good (due to the tighter k, and the heavier tank currents, and
there may be more gap and tank losses due to the lower
tank voltage at .031uF. I'm kind of surprised that it changed
the look of the sparks though. (but see below).
In my original old work that showed better efficiency at 60 bps, I was
using the 4" by 23" secondary with even looser coupling. This, along
with the smaller secondary (and a larger toroid), may have made the
difference.
Next I will try the larger 5" by 20" toroid, and I'll loosen the coupling,
and see if it's any better. I do not plan to spend a lot of time with
this 60 bps idea, despite its interesting and efficient qualities.
(I just went back and loosened the coupling, but sparks are shorter.
I tightened the coupling and the sparks emited from all around the
toroid. So the extra toroid streamers in the 0.031uF work were
probably due to the tighter coupling that might result from using
few primary turns.) The room was getting darker as the work
progressed, this may have made the sparks appear differently too.
In any case, these tests show once again that 60 bps and
120 bps are about equal in spark growth efficiency. It's possible that
there's a break-rate in between (such as 80 or 100 bps) that's even
better at these (and other?) power levels.
I once tried 30 bps, but the results were NG. This break rate is
probably too low for spark streamer coalescence in this TC.
This 60 bps work is a part of my efforts to see which break rates
are most efficient at producing long sparks. I'm not recommending
that anyone actually use 60 bps for their TC's.
Cheers,
John Freau