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New Coil Measurements
Hello everyone,
Due to the lack of good _reliable_ caps I cannot
undertake any repetitive firing (an absolute curse). BTW, would
somebody please post the following information on Condenser Products:
phone number, fax number, full postal address? It is clear I'm going
to have to try doing some kind of deal with the company due to the
additional expenditure sending caps hither and thither in a reasonable
amount of time is going to entail (not to mention the headache of
reversing customs charges etc etc.).
However, I have done some characterization of my new resonator
and done some single shot expts in less than ideal conditions (rotten
isolation). FYI:
Reiterating : Ls = 162mH, Hs=39", Ds=16.8", Cs(Med)=23pF,
Fr(projected)= 82kHz, n=1000 turns
Measured: Fr of bare resonator = 83kHz (Medhurst wins again), Q
"unloaded" = 230 odd (this is with poor isolation and I didn't bother
to check this with the topload). The resonator was mounted 16" off
the floor to get these but the top was never more than a couple of
feet from any object (sigh).
Interesting stuff: I dug out my 19" toroid (ring dia about 4.5"),
Cisolated calc'd around 15pF. I have previously measured the
capacitance at around 13 - 14pF above a much smaller coil. On this
occasion, mounting about 3/4" abpve the windings yielded an
_effective_ value of 4.5pF. Mounting it about 3" higher gave about
6.3pF - not the most effective topload in history. It only overhangs
the coil by an inch or so all round. At this setting, Fr = 73.1kHz.
Interesting to see how the mutual capacitance of a large resonator
and small topload decimates topload effectiveness.
Fp Cp Lp Ecp k Spark Vo(35k/") Vo(lumped)
84.8k 50n 70.5u 2.7J 0.23 12" 420kV 429kV
68.8k 100n 57.4u 6J 0.17 19" 665kV 640kV
66.5k 200n 28.7u 8.1J 0.18 22" 770kV 743kV
71.7k 200n 25uH 11J 0.15 25" 875kV 866kV
Notes: - interesting correspondence between spark length based on
35kV/" and theoretical lumped calc. This is almost certainly too high
as no losses in prim are taken into account. My guess is that 40kV/"
would be coming close. About 1 in 5 sparks formed a bright connected
channel with a wooden beam, piece of metal or grounded wire at the
distance stated (the coil is clearly demonstrated to be capable of
the length). I did measure a single attached streamer of 26"+ at the
highest energy. On 4/5 occasions, multiple streamers were heading off
the toroid dispersing energy in different directions. A number of
these exhibited clear forking.
- k's are approximate (BW/F) and vary wildly due to primary
coil combos used.
- I didn't have enough Lp for the 50nF cap. All other Lp's
gave the longest measured spark under these conditions.
- The caps used were two of my dry-fired polyeth caps. Corona
losses in them would have reduced efficiency - I'll take the storage
scope home and capture the decrements to get an idea of I^2.R losses
in the various primary cominations. I may be forced to use them in
repetitive operation with some microwave transformers to get my ozone
fix, but I have a serious problem - where to fire the darn thing
without setting something on fire. Arcs would almost certainly glue
themselves to the roof even at 100Hz rep rate and set the building
paper alight.
- at Ecp = 15J, theoretical Vo around the million mark.
Hope this is some use to Greg and others,
Malcolm
[From the archives:
The Condenser Products Corp.
2131 Broad Street
Brooksville, FL 34609
USA
Tel: 904-796-3561, Fax 904-799-0221
-- Chip ]