Re: Question on Ceiling Height/Material

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "James Zimmerschied" <zimtesla@xxxxxxx>

As a follow on... I measured the resonant frequency of my coil in the 
garage vs the shop. The difference was 175 kHz vs 170 kHz (not as 
much difference I would have thought given the coil tuning effect 
noticed). the shop has a standard 8' ceiling and has a flat metal 
roof. The garage has open trusses so is about 12' to the wooden roof 
which is at about a 30 deg angle from the floor plane.

For Bart, JAVATC was right on for the shop 170kHz measured vs 169.15 
Hz calculated. For some reason the garage is a different animal. 175 
kHz measured vs 180 kHz calculated.

Jim
----- Original Message -----
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To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
Sent: Saturday, June 03, 2006 10:22 PM
Subject: Re: Question on Ceiling Height/Material

Original poster: "James Zimmerschied" 
<<mailto:zimtesla@xxxxxxx>zimtesla@xxxxxxx>

hello Terry, Bart  and all,
I was out of town attending a funeral so I am behind on the ceiling
height conversation.

I did take the coil home and tried it in my garage on the same day-
it didn't start making sparks until I had loaded it with massive top
loads - and still not smooth as at the other location. My conclusion
was I needed to push the secondary frequency lower to correspond to
the trigger circuit frequency. Also I need to add some primary turns
for tuning.

Tomorrow I plan to return to the low room shop and try again. If
there is time I will take some equipment to measure Fres and compare
with the calculated value.
Jim
----- Original Message -----
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To: 
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Sent: Wednesday, May 24, 2006 11:23 AM
Subject: RE: Question on Ceiling Height/Material

Original poster: Vardan
<<<mailto:vardan01@xxxxxxxxxxxxxxxxxxxxxxx>vardan01@xxxxxxxxxxxxxxxxxxxxxxx>mailto:vardan01@xxxxxxxxxxxxxxxxxxxxxxx>vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Interesting....

His is a primary feedback system very close to this schematic:

<<http://hot-streamer.com/temp/DF-DRSSTC-SCHEMATIC.pdf>http://hot-streamer.com/temp/DF-DRSSTC-SCHEMATIC.pdf>http://hot-streamer.com/temp/DF-DRSSTC-SCHEMATIC.pdf>http://hot-streamer.com/temp/DF-DRSSTC-SCHEMATICpdf

I must wonder too if the problem is not a loose wire or some other cause...

I suppose the feedback coils sort of automatically "adjust" to a
point...  Interesting...

Cheers,

          Terry

BTW - The inductor I made for the SISG MOT system would be good for
the DF-DRSSTC *:-)))  But maybe the DCR is too high.....??

At 12:08 PM 5/24/2006, you wrote:
 >With a feedback driven system, i don't see proximity effects changing
 >the operating parameters so much as to not make it work, assuming of
 >course you are driving it with feedback.
 >
 >Dan
 >
 >
 >
 >
 >I recently noticed that the ceiling height and material can make a
 >significant difference in a coil's secondary frequency.
 >
 >Case in point - I was trying to get my DF-DRSSTC working. I couldn't
 >get it to break out properly and it was drawing too much current. I
 >took the coil over to a friend's house and it was working well - got
 >18" arcs to a ground rod - with no change in the coil configuration.
 >What was the difference? My friend said his shop which has a flat
 >metal roof, suppresses the operating frequency of his coils. When he
 >moves them outdoors, they have to be retuned. When I was trying to
 >run this coil before, I was in my garage which has no "ceiling" only
 >open rafters up to the roof.
 >
 >In playing with parameters in JAVATC, I see a noticeable change
 >between an 8 ft ceiling and a 12 foot ceiling. I don't see anything
 >in the program that inputs the material type for the ceiling. I would
 >think a non-conductor like gypsum wallboard would have less effect
 >than a flat steel roof. Maybe Bart could shed some light here.
 >
 >The bottom line for me is to accurately model the room envelop when
 >running a TC modeling program. Also, if you relocate the coil - say
 >from in the garage to out on the drive way - expect to have to retune
 >(possibly reconfigure).
 >
 >Jim Zimmerschied