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Re: Scoping Work Coil

Greetings all,
                     I received this request offlist today. To save myself 
the trouble of having to repeat this once more, here are the specs 
for the coil (it must be in the list archives BTW - I have given them 
several times already):

To:             	malcolm.watts-at-wnp.ac.nz
Date sent:      	Mon, 13 Dec 1999 20:26:04 -0500
Subject:        	Re: Scoping Work Coil
From:           	Grayson B Dietrich <electrofire-at-juno-dot-com>

> Malcolm, 
> 
> could you please tell me where (if) info of this incredible coil is
> located online? I've looked and don't seem to have saved any list emails
> containing it, so....

Transformer:
C-core - originally manufactured by Leybolds of Germany.
Core section: 1.5" x 1.5" approx
Length across top: 6"
Height 7"
(you can work out Ae, Le etc.)
Primary: currently 450T 1mm wire, connected straight to 230VAC 
mains
Secondary: 10,000T (around 0.2mm wire I think).

Warning: attempting to judge the efficiency of the TC by measuring 
the input to this transformer will result in a horrendous figure. The 
core is almost saturating and the windings get b***** hot very 
quickly. Copper is miles too small.

Cp: 0.1uF  MMC (used to be ext'd foil poly)  10.5kVDC working 
voltage

Lp: helical, 4 turns of 3/8" Cu pipe, diameter about 25", height about 
4", no taps, about 18uH from memory. Bottom turn of primary is 
level with the bottom turn of the secondary.

Gap: single static with 1/2" rounded W-C electrodes brazed onto 
brass rods which are in turn mounted in brass blocks. Best 
performance requires a very moderate airflow through the gap. Too 
much air prevents the gap firing regularly if at all, too little or none 
results in gap heating up more quickly and power arcing after a 
short time. Gap setting approx:47mils (imperial, not metric).  

NOTE: I'd welcome anyone telling me what voltage they think that 
gap is likely to fire at in repetitve running.

Ls: about 45mH, a shade less than 10" diameter, winding height 
about 45", spacewound with 0.56mm polyesterimide coated copper 
wire, wound by bifilar winding two lengths of the wire and removing 
one (carefully) after winding was finished. 

Cs about 19pF or so (Medhurst)

Fs (with terminal) about 130kHz (so you can work out Ctot, Ctop)

Terminal: "filled-in" donut, 11" high, dia about 24". Made from 
polystyrene foam covered with several thicknesses of Al cooking
foil. Note: ROC is smaller than 5.5" as the sides flatten out.
With the gap set to fire at around 7.5kVDC (measured), this terminal 
operates on the edge of breakout. A perfect shaped donut would not 
breakout at this energy level.

K measured at 0.12 or thereabouts. I haven't tried altering k since 
the primary coil position is fixed.

There is a picture of the coil running (PRIOR to its recent upgrade) 
on funet in the picture gallery I think.  A run (with the terminal and 
tuning detailed above)  last night resulted in a stray streamer hitting 
the metal slats in the ceiling about 57" above the top of the terminal. 
The coil regularly attached to objects four feet away.  

It is hard to believe there is anything special about this coil except to 
say that measured with great isolation, the Q is by far the highest of 
any secondary I've built so far.

Regards,
Malcolm

> thanks,
> 
> Grayson Dietrich
> http://www.electrophile.8m-dot-com
> 
> 
> 
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