# Re: MMC Question.

Original poster: Mddeming@xxxxxxx
Hi Gerry,

You are, of course, mathematically correct. I was attempting to come up with an easy to visualize, intuitive explanation for someone who is enthusiastic, but to whom the math and theory seem to still be somewhat of an amorphous cloud. IMO, Ipeak = Vfire / sqrt (Lp/Cp) is anything but visual or intuitive, but it certainly IS accurate as long as R ~ 0.

Matt D.

In a message dated 8/9/06 12:31:03 A.M. Eastern Daylight Time, tesla@xxxxxxxxxx writes:

On 8/8/06, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: "Gerry  Reynolds"
<<mailto:gerryreynolds@xxxxxxxxxxxxx>gerryreynolds@xxxxxxxxxxxxx>

Hi Matt,

The issue isn't the 60ma charging the caps. The issue is when the
spark gap fires, the only thing limiting the current is the reactance
of the TC primary inductance.  Any resistance in the cap, copper
tubing, and spark gap plasma will be insufficient to prevent very
very high currents.  The resistance of the CU tubing and caps (esr)
is in milliohms.  The SG plasma may be 2 to 5 ohms.  If this was all
limiting the current, you would have 4000-10000 amps.  It is the
inductance that really limits the current.

Ipeak = Vfire / sqrt (Lp/Cp)

Hope this helps,
Gerry R.

>Original poster: <mailto:Mddeming@xxxxxxx>Mddeming@xxxxxxx
>In a message dated 8/8/06 3:18:05 P.M. Eastern Daylight Time,
><mailto:tesla@xxxxxxxxxx> tesla@xxxxxxxxxx writes:
>Original poster: "Glen McGowan"
<<mailto:glen.mcgowan@xxxxxxxxx>glen.mcgowan@xxxxxxxxx>
>
>Thanks for the extra effort regarding the caps.
>
>Regarding the peak current, both Charts show the same values for peak
>current. I must be missing something(?). I'm not building a beast by
>any means. But,this is my first coil and plan to power it with a
>15/60 NST. My MMC will use 16 of the STK's in series.
>
>Wouldn't the current remain at 60mA throughout the tank?
>
>I'm all ears, still learning so everything is educational at this
>point. As long as I don't stop my heart I consider it a learning
>experience. I would like to avoid the "power up and run for the
>hills" avenue as much as possible.
>
>Hi Glen,
>
>     I believe you are confusing the charging current with the
> discharge current. and the rms value with the peak values. Let us
> consider an idealized Tesla Coil running at 150 KHz and 120 BPS.
> True, the cap is charged 120 times per second (60Hz supply) at a
> rms current of 60 mA. However, when the gap fires, all those
> electrons that accumulated on the plates of the capacitor in 1/120
> of a second are now removed in 1/300000 sec - 2500 times faster.
> Since current is coulombs per second, The discharge current for
> that first half cycle could be 2500 times higher than the charging
> current. In this case 150 Amps if only for a few usec. It is this
> kind of slamming that eats up all but the most rugged caps.
>
>Matt D.