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RE: Peak Primary Current

Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>


Thanks Jim.

I see it now.  The amps are sky high, but for such a short time that the
power dissapation is negligible.

For my small coil, I run 460 BPS RSG so I have 2200 uS to charge the cap
between bangs.
The scope shows that quenching occurs before the first notch in about 40
uS.
These actual values don't change your important point.
Thanks again.

Mark


Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>

Ooops.. I misdivided.. see below..

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, April 20, 2005 11:04 AM
Subject: Re: Peak Primary Current


 > Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla@xxxxxxxxxx>
 > To: <tesla@xxxxxxxxxx>
 > Sent: Wednesday, April 20, 2005 9:14 AM
 > Subject: RE: Peak Primary Current
 >
 >
 >  > Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>
 >  >
 >  >
 >  > Antonio, Terry:
 >  >
 >  > Thanks for response.  My testing confirmed Gary's
observations(Gary's  >  > tests very interesting).  This contradicts old
common "coilers" belief  >  > that heavy gauge wire is required for
primary connections.  >  >  >  > I see I forgot Pi in the formula(Thanks
Antonio for pointing out).  >  > So Imax = 2*Pi*Fres*V*C  >  > This
makes Imax Pi times the values I had calculated so current is even  >  >
higher than I thought.  I still can't believe I can push that much  >  >
current through #14 ga wires with no significant heating!!  I realize  >
> each cycle is only 2uS and ring-up is only 10 uS with 1st notch at
40uS.  >  > So the duty cycle is quite low... 40E-6 seconds of current
flow with 8666E-6  > seconds between bangs.  Ball park there is about
1/200..  Even though the  > power is the current squared, the small duty
factor (0.005) means that  > average power dissipation is quite low.
For instance, if your rms current  > (during the bang) is 100 A, and the
resistance of the wire is 0.01 ohm, the  > peak power dissipation is
100*100*.01 = 100W.  The average power dissipation  > would be only 1/2
watt in this case, though.

That's 8333E-6 seconds, not 8666.. No matter, the basic idea is still
the same.