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Re: [TCML] Glass Plate Capacitor


Your glass cap will work at higher voltages if the wax is well impregnated into the plate edges. We built a coil in high school with 18 one-gallon mayonnaise jars wrapped with foil on the outside and filled with salt water. We later lined the insides with foil too. Much lighter. We ran our coil on two 15-30s in parallel. It worked great and we never had a cap failure. I think the walls of the jars are about the same thickness as single-strength glass.

Check this out for the dissipation factor of glass. It seems to be between 0.002 and 0.007 according to this old but fun paper--


and better than that according to this modern one--


in the area of the better plastics


The only disadvantage of the flat plate design is that you don't get the cool ring of blue surface discharge at the edge of the foil around each jar. (There goes the ol' dissipation factor, probably.)

My advice is --- INCREASE  THE  MEGAVOLTAGE!!!

We used THE SAME BOOK! I still make coils that are fatter than they need to be. Our copy was lost sometime in the last 50 years. What is the name and other info so I can search for another one?

Have fun---


On 4/13/2015 3:59 AM, b alex pettit jr via Tesla wrote:
Hello All,
I have been in the process of getting an old build operational again.I constructed this RSGTC back in the mid '80s based on info from a book published in 1920.  It is of classic design in thatthe Secondary is wide and short  by current day designs ( 8" dia x 15" hi ) and has no top load - just a small 1"  brass ball on a short post. It creates a very large brush discharge from the top turn and equal length sparks from the ball.It looks like a true antique as the components have nicely finished wood bases and boxes.
It was built using a surplus military grade 5KV 90 ma transformer and
is throttled by a tapped inductor of my design on the AC input. Thecapacitor is a 2" stack of  'single strength' window glass and aluminum foil whichwas immersed in hot beeswax such that the edges of the glasspanes are sealed ..  The foil comes to within 1/2" of the edges of the glass.
The cap measures  0.025 uF.  Input 5KV max.  ARSG runs at 360 BpS.
The coil resonance measures 290 KHz and this agrees with the JavaTC analysis. Coupling 0.3 k
I have Never attempted full power operation as there were always pri to sec arc-overs.I finally fixed this ( after 30 years !  ) by sleeving the upper turn of the primary with plastic tubing.
Question : Whats the probability that the Capacitor withstand full 5 KV transformer output ?
Regards,AlexOrlando FLKK4VB

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