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RE: Capacitor help



Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 


Mark -

Thank you for clarifying my post. It is obvious I should have reread what I
wrote. Each of the capacitors should be in parallel with a 10 meg resistor.
However, this is not necessary if the capacitor is connected across the NST
secondary because the capacitor will be discharged by the secondary
windings. Of course, like any capacitor it should be considered charged
until you discharge it yourself.

This has brought me back to reconsidering the selection of the TC primary
capacitor.
This capacitor should be selected to meet the following conditions otherwise
it will not be charged to the design voltage during TC operation.

      1. Power - The NST must have sufficient power to completely charge the
capacitor during the available charge time. Easy to determine.

      2. Charge Time - This is determined by the BPS and RC constant of the
primary circuit. If you don't check this time your pri cap is probably not
being charged to the design voltage. Difficult to determine.

      3. Tuning - The pri cap must be sized for proper tuning of the pri
circuit to resonate with the secondary circuit. Easy with a computer
program.

John Couture

-----------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, December 12, 2003 9:57 PM
To: tesla-at-pupman-dot-com
Subject: Re: Capacitor help


Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org>

Just so there is no confusion, John means to connect the resistors in
parallel with each capacitor to discharge the capacitors after power is
removed.

IMO .015uF is too large for a 9/30NST.  A single string of 8 .10uF "geek
caps" gives a value of .0125uF at 16kV, which is what I recommend.  I would
probably order 10 caps, though. ;)

OTOH, if there are financial constraints, it's hard to beat a bottle cap.

Good luck!

Mark Broker
Chief Engineer, The Geek Group

On Fri, 12 Dec 2003 12:24:38 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:

<snip>

 >tune. What could be easier? The MMC caps are the best way to go. Buy 10 CD
 >.15uf, 2KV caps and connect them in series with 10 meg resistors. This will
 >give you .015uf 20 KV, .01875 16 Kv, etc, cap values to play with. Have
fun.
 >Let us know how you make out.
 >
 >John Couture