Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
Keep in mind that output voltage is no indicator of spark length.
Spark length is a function of power input and pulses/sec off the HV
terminal. It is a plasma corona "growing" effect and that's why
using strict voltage calculations to produce long sparks isn't that
relevant in Tesla transformers.
Most systems respond favorably with a 1,400 to 1,600 turn closewound
secondary inductor running with NST power supplies. Systems with
pole xmfrs work favorably with a 1,000 to 1,200 turn sec.
inductor. Tesla coils like a lot of "power" for good spark
output. John Freau's equation works well to predict this behavior.
System Q factor which is normally critical for switching circuit
applications is not that important in Tesla coils --- at least not
as important as a lot of power in the system.
Richard Hull's record of spark length = 13 x secondary inductor
length was achieved driving a 4 inch dia. coil which featured over
1,000 turns of fine stranded closewound enamel magnet wire, I
believe it was around #28 or # 30 AWG. A very tiny sec coil
closewound delivering 11-12 ft long sparks!! It was amazing to see
in operation.
Dr. Resonance