RE: what to use for resisters on my bank

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

As far as relating the resistance value to the number of capacitors  -
the number of capacitors used is irrelevant.  Only the total capacitance
value is pertinent.

Regarding my suggestion that a 15 second discharge period was OK -
perhaps that IS slightly on the long side.  I think I built the resistor
when I was using a single .02uF cap, so the discharge time was half of
the 15 seconds.  But being the devil's advocate, the 15 seconds does
assume that the cap was charged to the peak charging voltage of 21kV.
It's just as likely that the voltage would be anywhere else between zero
and 21kV when the fault occurs, and the discharge time would be
proportionally shorter.  Yes, this is reckless rationale!

Regards, Gary Lau
MA, USA


> Original poster: John <guipenguin@xxxxxxxxx>
>
> Yeah, I would never build a safety gap for a capacitor bank, thats
> like shorting the bank out manually with a screw driver.
>
> What is a good resistance to use? Would you say a series of resistors
> about 10M for every 1 capacitor?
>
> Thanks,
>
>       John.
>
>
>
> On 10/5/06, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
wrote:
> Original poster: "Lau, Gary" <<mailto:Gary.Lau@xxxxxx>Gary.Lau@xxxxxx>
>
> Since your caps are in parallel, you can't put individual resistors
> across each cap, since each resistor must be rated for the total
voltage
> of the array.  You need to construct a series array of resistors.
>
> I needed a bleeder resistor across my Maxwell cap.  I happened to have
a
> bunch of 2Meg 1/4W resistors, so I built an array of 39 of them on a
> piece of perfboard.  A photo may be seen about half way down on my
sync
> gap page at
>
<http://www.laushaus.com/tesla/sync_gap.htm>http://www.laushaus.com/tesl
a/syn
> c_gap.htm.
>
> BTW, in the image you referenced on the Powerlabs site, I hope that's
> not a "safety" gap in parallel with the caps?  Caps of this type are
the
> least tolerant of the super-high current that would result from such a
> gap firing!  Safety gaps should only be placed in parallel with the
main
> gap, so that the discharge current is safely limited by the primary
> inductance.
>
> Regards, Gary Lau
> MA, USA
>
>
>  > Original poster: John
<<mailto:guipenguin@xxxxxxxxx>guipenguin@xxxxxxxxx
> >
>  >
>  > I have some strontium titanate caps (yes I know they will slowly
>  > loose capacitance over time) each rated at about 50kvdc 910pF,
>  > (safely about ~20 or so kv ac), which I will be using on my first
>  > coil until I get some mmcs down the road.....
>  >
>  > The entire bank will be 0.01uF. My bank will look (similar) to this
>  >
>
<<http://www.powerlabs.org/images/tccapbank.jpg>http://www.powerlabs.org
/imag
> es/tccapbank.jpg
>  >http://www.powerlabs.org/
> image
>  > s/tccapbank.jpg
>  > between two sheets of Lexan.
>  >
>  > what should I do about resisters like I see on all mmc banks?
>  >
>
>
>
>