Re: Bleeder resistors

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Ben,

At 07:01 PM 7/26/2002 -0700, you wrote:
>Hi all, 
>  I wanted to make sure I got this right.. 
>
>After chugging out some equations I figured out that I'll
>need a 410 meg bleeder for my .01uF 75kV transmitter cap.. 
>
>Does this sound right? I figured a max voltage of 75kV
>because I wasn't srue what the max voltage on the cap would
>be with a 15/30 resonant charging.. 

The maximum voltage should only get to around 21kV where the spark gap
should fire.  The resonant size for a 15/30 is 0.0053uF.  A static gap LTR
size is 0.008uF and a sync gap LTR is 0.0138uF.  Perhaps you have a 15/60?
See chart at:

http://hot-streamer-dot-com/temp/MMCcapSales.gif

A 10uF cap will probably work in any case, just a little roughly.

>
>With max 15kV, it takes 10 seconds to get down to 50V. Is
>that right? If so, is the time constant long enough that it
>doesen't interfere with the coil's operation?

It take this long for a cap to discharge across a resistor:

T = 5 x R x C

So   5 x 410e6 x 10e-9 = 20.5 seconds

The power dissipated is Vrms^2 / R  so  21000^2 / 410e6 = 1 watt total

I thing you could probably got down to 100 Meg  for 5 seconds at 5 watts.

Cheers,

	Terry


>
>Thanks for any help!!
>
>Coiling in Pittsburgh
>Ben McMillen
>
>