RE: NEW COIL FIRING!
Subject: RE: NEW COIL FIRING!
From: mark.graalman-at-mediccom.norden1-dot-com (Mark Graalman)
Date: Mon, 30 Jan 1995 17:54:00 -0500
>Received: from dialup.oar-dot-net by csn-dot-net with SMTP id AA23260 (5.65c/IDA-1.4.4 for <tesla-at-grendel.objinc-dot-com>); Mon, 30 Jan 1995 19:19:43 -0700
Resent-Date: Mon, 30 Jan 1995 21:18:21 -0500
NTAC> Message-ID: <9501301700.AA00449-at-grendel.objinc-dot-com>
NTAC> Newsgroups: tesla.list
NTAC> From richard.quick-at-slug-dot-org Sun Jan 29 01:13 MST 1995
>Received: from uustar.starnet-dot-net by csn-dot-net with SMTP id AA13323
NTAC> (5.65c/IDA-1.4.4 for <tesla-at-grendel.objinc-dot-com>); Sat, 28 Jan 1995
NTAC> 17:29:43 -0700
NTAC> From: richard.quick-at-slug-dot-org (Richard Quick)
NTAC> Subject: RE: NEW COIL FIRING!
NTAC> Date: Sat, 28 Jan 1995 17:06:00 GMT
NTAC> To: tesla-at-grendel.objinc-dot-com
NTAC> * Originally By: Bhaley-at-shore-dot-net
NTAC> * Originally To: Richard Quick
NTAC> * Originally Re: RE: NEW COIL FIRING!
NTAC> * Original Area: UUCPE-Mail
NTAC> * Forwarded by : Blue Wave v2.12
NTAC> Date: Sat, 28 Jan 1995 05:36:57 -0500
NTAC> To: richard.quick-at-slug-dot-org (Richard Quick)
NTAC> From: bhaley-at-shore-dot-net (Brendan Haley)
NTAC> Subject: Re: New Coil Firing!
> * Original msg to: Tesla-at-grendel.objinc-dot-com
> > From: bhaley-at-shore-dot-net (Brendan Haley)
> BH> The question is: the winding stops about 4 inches from the
> BH> top of the pipe. There is one sweeping wind from the end of
> BH> the tight winding up to the top, where the discharge
> BH> terminal is. Does this spread out the capacitance along
> BH> this long wind, and away from the terminal. I have noticed
> BH> that there is corona all along this wind, and the sparks
> BH> seem to get stronger near the tight winding.
> BH> I am planning to cut off the rest of the pipe anyway, but I
> BH> am curious as to whether my intuition is correct (allthough
> BH> I doubt it)... Any kind responses are appreciated. Thank you
> BH> -Brendan
>The only problems you are having is that: your discharger is
>mounted too high up off the top of the secondary winding; your
>discharger is too small in diameter; or both.
>Cut the coil form down to 1 inch above the winding, and properly
>cap the coil. I just use scrap pieces of squarely cut PVC pipe as
>insulating spacers to change and adjust the height of the
NTAC> Not to harp on the subject, but why does the distance between the
NTAC> winding and the discharger matter: i.e. what physical phenomenon is
NTAC> occurring. Is it extra resistance from the wire, or capacitance?
NTAC> Normally I would envision the points as electrically equivalent,
NTAC> regardless of this length.
NTAC> I know I am wrong in assumming this, and I am curious as to why.
NTAC> Also, while I'm asking, what purpose does the discharger serve? A
NTAC> coil still produces the wireless power transmission without the
NTAC> capacitive hat.
MG> Each ajacent turn in a coil makes a small capacitance, the top turn on
the secondary has no ajacent turn above it, so it will allow a corona to
occur if there is no terminal, or if the terminal is too high. The terminal
if it is large enough in capacitance, will become "dominate" in comparision
to the distributed/stray capacitity found in the coil itself, thus it
in effect draws the energy out of the coil, and re-distributes the current
in the secondary. The terminal also stores the energy in between "bursts"
and since the energy is stored "outside" of the coil capacitance, it
increases the power handling capability of the secondary coil.
NTAC> And finally, could you explain the role of the spark gap. I've seen
NTAC> it described as providing "harmonically rich" current in order to
NTAC> cause the tank circuit to oscillate. That is both nebulous and
NTAC> suspicious sounding to me. Is the spark gap width important in the
NTAC> tuning, or is it fine merely sparking?
MG>*Tesla coils are harmonically rich because they are really a "dirty" RF
transmitter, the spark gap doesn't cause the oscillation, it allows it to
occur. The "source" for the primary oscillations is the capacitor, not the
transformer, not the spark gap. If there were no spark gap, and the
capacitor and coil were connected together, the coil would short out the
capacitor and you couldn't charge it, if you opened the circuit to charge
the capacitor, once you had it charged it wouldn't be able to discharge
through the coil. You would have to manually re-connect the capacitor to
the coil let it "ring out" then disconnect it and recharge it again, this
is done for you by the spark gap. The gap width is VERY IMPORTANT in that
it dictates how high the voltage will build in the capacitor before it
fires, it effects the resistance in the "loop" during oscillation and
therefore the "Q" of the primary, it affects the ability of the gap to
"quench" properly which affects EVERY aspect of the coils operation.
* meaning "disruptive discharge coils"
NTAC> Sorry to ask so many questions, but now that I finally got the thing
NTAC> working, somewhat, I am filled with curiosity. I was hesitant to
NTAC> ask these questions until I had a working coil, and now I feel more
NTAC> So, any suggestions that would help me on my quest to becoming a
NTAC> better coil builder are greatly appreciated.
MG> Keep building and document your results, there really are no short cuts
to a tesla coil education
Mark Graalman TCBA #1399
NTAC> P.S. Thanks for the congratulations
NTAC> ___ Blue Wave/QWK v2.12
... Alias, Mark the spark
___ Blue Wave/QWK v2.12