Re: Awesome Quarter Shrinking Capacitors on EBAY

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net> 

Tesla list wrote:

>Original poster: "RIAA/MPAA's Worst Nightmare" <mike.marcum-at-zoomtown-dot-com>
>Good point. With a few 50kJ tests without blowing anything up except air I
>realized I'd have to treat the work coil as a bomb (sounds like one with
>air). I thought manhole covers were iron? What if I used higher and higher
>voltage in the coil (30kv limit at the moment, but can go much higher with
>more caps and a rectified x-ray xformer (125kv), though I'd have to move to
>the middle of nowhere). I agree nickels are stubborn (thanks to the weird
>nickel alloy), but new (1983+) pennies are totally warped (not just shrunk)
>with just 2500J (my first "shrinker") since they are mostly zinc. It seems
>old pennies would be a perfect candidate since they are almost pure copper
>(if you can remove the tarnish since they are hard to find without it). I
>never tried it after the zinc penny goof (turned out to be a blob of
>unrecognizable metal).
>  > Hi all,
>  >
<SNIP>

Mike,

This is getting pretty far off Tesla Coiling - you may wish to move the 
discussion over to the HV List. The "sweet spot" for shrinking is a work 
coil voltage between 10 - 25 kV. If you try to go significantly higher, 
coil flashover becomes a serious problem - strong magnetic forces crush the 
coil axially, in the process crushing the insulation that separates 
adjacent turns. This causes flashover of the work coil before the current 
peak can be reached, reducing the effective compression force that is 
transferred to the coin. Bottom line - at higher voltages you'll make a 
bigger bang, but the shrinking power is actually reduced. Once you begin 
winding coils and discharging them be extremely careful - the hypervelocity 
fragments are ejected with surprising force - these little  pieces of 
shrapnel can blind, maim, or even kill an unprepared experimenter.

BTW, older pennies (Indian Heads and Wheat pennies through 1942) were made 
from bronze (95% Cu, 2.5% Zn, 2.5% Sn), and wheat and Lincoln Memorial 
pennies made between 1944-1981 were brass (95% Cu, 5% Zn). After 1982, they 
are copper plated zinc. For a variety of reasons, Indian Heads and old 
Wheat pennies work the best.

Best regards,

-- Bert --
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