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would a 15kv 5ua DC transformer work for TC




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From:  Antonio Carlos M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent:  Monday, February 23, 1998 12:20 AM
To:  Tesla List
Subject:  Re: would a 15kv 5ua DC transformer work for TC

Malcolm Watts wrote:

> The equation V = i x t/C  would be helpful here. Let's say you want a
> break rate of 100 Hz.  You have 10mS to charge the cap roughly.
> Assuming the supply *is* constant current up to 15kV, you can find a
> value of C that meets this requirement:
> 
> C = 10^-5 x 10^-2/1.5x10^4 Farads = 6.6pF    not too good really.
> 
> Perhaps someone had better check my arithmetic.

It is correct, but... 
Using the relation Voutmax=Vin*sqrt(C2/C1), and considering that C2
would be at least some 6.6 pF (only the self-capacitance of the
secondary coil), we obtain:

break rate   capacitor   maximum output voltage
100          6.6 pF      15 kV
10           66 pF       21 kV
1            666 pF      150 kV

A low-current supply can still produce some impressive output, if
you can make a low-leakage capacitor with 600 pF or more and use
a very low break rate. A large Leyden jar capacitor would be adequate. 
With one break per second, the available energy for each discharge
would be 0.5*666e-12*(15000)^2=0.075 Joules, what can result
in a rather weak, but clearly visible, spark several inches (~3) long
considering the 150 kV.
(Some day I will try something like this using an electrostatic machine
to charge the primary capacitor, but with 60 kV instead of 15 kV.)

Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq