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Re: Question on Ceiling Height/Material

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Jim,
Thanks for doing the measurements. What you've measured makes sense. The shop layout is a better representation of the ceiling object in Javatc than are the open trusses and angled ceiling in the garage. Because of the trusses and angled ceiling (same as my garage btw), the ceiling height will need adjustment in the program to compensate. Now that you "know" the difference, it's easy enough to alter the ceiling height in the program to attain the measured output. From now on, you can build future coils with known values in the surrounding inputs that match your particular garage for greater accuracy. 

Great job with those measurements!
Bart

Tesla list wrote:


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 -----
From: <mailto:tesla@xxxxxxxxxx>Tesla list
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 -----
From: <<mailto:tesla@xxxxxxxxxx>Tesla>mailto:tesla@xxxxxxxxxx>Tesla list
To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx 
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