[Prev][Next][Index][Thread]

Re: Arc Impedance Study

At 07:56 PM 10/9/98 -0700, you wrote:
>> Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
>
>> >A curious thing: the 1/(2*pi*RC) frequency for 197K and 21.3pF is 38kHz.
>> 
>> In fact, it is exact!  F=1/(2*pi*R*C) is equivelant to R=1/(2*pi*F*C) which
>> is also equal to the capacitive reactance Xc=1/(2*pi*F*C) which is the
>> basic definition I used to calculate the 197k ohms.  ;-))
>
>But then why doesn't the same thing work on your coil,
>with 282K, 3pF, and 111kHz?

I incorrectly stated, in the original post, that 197k ohms was the real
resistance, it was not.  226k ohms was the real resistance and 197k was the
capacitive reactance.  Of course, the capacitive reactance worked out in
that equation.

In my coil, I never stated the capacitive reactance, just that it was the
equivalent of 3pF.  To find that reactance you use Xc=1/(2*pi*F*C) ==
1/(2*pi*111000*3^-12) == 477.94k ohms of capacitive reactance.  If you find
the magnitude of this reactance with the real resistance of my coil (282k)
You get 554.93k ohms (there is a little rounding error from the 563k is
stated in the original post).  Obviously, the equation F=1/(2*pi*R*C) is
the same equation used to find the reactance in a little different form so
it works right out.

>
>
>> It seems to favor the positive peaks somewhat.  I will have to look at this
>> specifically this weekend to really see if that is true.
>
>Mine favors the pos peaks as well, which agrees with 
>the published literature on polarity preferences of 
>sphere-to-plate spark gaps.
>
>Keep up the good research, you're definitely 
>pushing the knowledge front in the area of 
>arc creation and maintenence for TC's.
>-- 
>

Perhaps with longer streamers, the positive peaks are more apparent??  I
would suspect it is one of those anode cathode things......

	I hope to play with spice models this weekend to see if there are any
great things to be learned.  Since most people's coils put out about four
foot arcs, the arc can simply be switched in as a load of 220k ohms plus
say a 5pF cap.  The computer can crank away and see what improvments are to
be had.  Hopefully, I can modify my coil to match those better virtual
systems and see if there is any real world improvment.  It would probably
take a controlled study with a single somehow adjustable coil to find the
sweet spot and match it to all this impedance stuff but this is at least a
good start.

Always much more to be learned :-)

	Terry

>
>-GL
>www.lod-dot-org
>
>
References: