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add. help needed
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From: solva-wijnschenk [SMTP:solva-at-xs4all.nl]
Sent: Sunday, February 01, 1998 2:11 PM
To: bert pool; DR.RESONANCE-at-next-wave-dot-net; john freau; richard hull; tesla-at-pupman-dot-com
Subject: add. help needed
Dear all,
I just started to build my second coil but seem not to be able to get
out any spark anymore!! Since I am calculating as much as possible to
start in the right 'ballpark' this startles me very much and maybe
somebody can advice me....!
1st coil:
-9000V, 30mA 120 V NST connected to 220V->output not measured
-saltwatercap ~0.02uF
-Static Gap approx. 1x1 cm
-17 turns copper wire helical primairy, 4.5 windings/inch, 10 inch
diameter
-PE-form, 68 windings/inch, 4.33 inch diameter, 33.66 inch height,
0,35mm diameter copper wire (=AWG 28?)
-Toroid (2,0 inch x 9,7 inch) + (1.6 inch x 8,5 inch)
-Measured sparklenghts: approx. 10-12 inch
2nd coil:
-2xmicrowavexfr 2,3 KV, 700mA in series swung up to approx. 9KV
-0,232 uF
-Static Gap approx. 3x0,3 cm
-17 turns copper wire helical primairy, 4.5 windings/inch, 10 inch
diameter
-PE-form, 68 windings/inch, 4.33 inch diameter, 33.66 inch height,
0,35mm diameter copper wire (=AWG 28?)
-Toroid 2x(2,0 inch x 9,7 inch) + (1.6 inch x 8,5 inch)
since this 2nd coil had to become an 'in between' coil for my 3rd coil
it bothers me very much that my calculations proved to completely
wrong. Please show me where i went wrong..... and mind the 50Hz instead
of 60 Hz...!
Questions:
I'll get two 7000V/700mA xfrs and a variac to power my third coil. Since
I want to have many turns on my primary to get it a bit unsensitive for
exact tuning, I think I need a much smaller prim.cap then needed for
xfmer-cap resonance. Calcs give me a cap for 0,16uF. Since my sec.coil
dimensions give a 94,8 Khz resonance freq, prim. induct. must be 17,62
uH.
1) is this calc for prim cap right?
2)suppose safetygaps are set to fire at 20KV, what is stored energy in
cap?
3)Is it better to take a smaller cap to get a bigger needed inductance
for the prim coil?
4)is it true that with a bigger prim.coil inductance, the induct. of
other leads is less influencing?
I think sec coil must be tuned to 94,8 Khz as well. But how do I
calculate the needed sec. topcapacity.
5)is the 94,8Khz right calculated?
6)I calculated an secundaire inductance of about 69029,23 uH and a
secundairy capacity of 25,19 uF but both values seem to be far to
big!?!?
for sec. resonance at the calculated frequency of 94,8 Khz I quess I
need to tune the sec. inductance, sec. capacity and topcapacity.
7)is this right? and do the additioned coil capacity and topcapacity
just have to match with the coilinductance?
8)I dont have enough walloutletpower to let the coil run on 14KV/700mA.
So I should use the variac. But how does this influence calculated
values and what should I adjust?
9) where can I find good calculations to build rf-safety coils between
caps and transformer?
I hope you can help me a bit further. Thanks on forehand,
Arwin Wijnschenk
The Netherlands
PS.1: a good supply for rolled caps are magnetrons. many caps connected
give high voltage withstanding and high values.
PS2.: next to NST's the signshops use 7KV/700mA xfrmrs as well to burn
dirt out of neonglasstubes