Re: Variation of secondary Q

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Paul,

At 12:36 PM 3/13/2002 +0000, you wrote:
>It occured to me that if someone has one of those nice digital
>scopes that can be remote controlled over a serial RS232 connection,
>then they would be able to carry out an interesting experiment.
>
>A TC secondary is set up and driven by a low frequency, sharp
>edged square wave into the base, so that the coil rings down at
>its 1/4 wave Fres at each edge.
>
>The scope captures the base current waveform and downloads to the
>PC.   
>
>A PC program analyses the trace to determine both Q and Fres by
>matching the ringdown waveform to a function 
>
> A * cos(w*t+theta) * exp(-rt)
>
>and finding the parameters A, theta, w, and r which give the
>closest (least squares) match to the waveform.
>
>A 2048 point trace would give around 0.1% accuracy on the Fres
>measurement, and an 8 bit vertical resolution would give about 
>0.4% accuracy on Q.
>
>The program could be left running for a week or two, recording the
>values of Fres and Q into a data file which could then be compared
>with environmental factors.
>--
>Paul Nicholson
>--
>

I have the HP 33120a arbitrary function generator (it does do square waves
:-))) but it can do any 16000 point 12 bit function if that is of any use here.

I have the Tek 3012 that does 10,00 point 9 bit captures and can put them
in a data file to floppy disk.

I have the low Z amp and Pearson 4100 1:1 140Hz-35MHz current probe.

I have a sheltered undisturbed outdoor spot I can put the coil and run coax
indoors to the toys.

I can monitor outdoor temperature but I am pretty helpless on relative
humidity measurement except for the local weather man's numbers for
humidity (+-2000% ;-p)  Colorado State University's little weather station
is only a few hundred yards away.  I wonder if its data is on the Internet
somewhere?...

http://www.atmos.colostate.edu/Weather.html

http://ccc.atmos.colostate.edu/cgi-bin/wx_form.pl

I think that's it ;-))

This time of year in Colorado, the outside condition vary drastically.

I don't think the scope will do automatically timed captures to disk (have
to search through it's zillions of functions) but I could use a wall clock
and push the button manually.  I was too cheap to by the RS-232 interface
when it is its own computer.

So I think we got the of the stuff here 

If you can figure out the computer "A, theta, w, and r which give the
closest (least squares) match to the waveform" part, I can supply the raw
scope data files.

So if I put the big coil's SonoTube secondary out there with the stuff
hooked to it and take a bunch of data files at various times and note the
conditions the best I can... would that be ok?  I can do the smaller PVC
form too, but not both at the same time.

http://hot-streamer-dot-com/temp/PaulsQexp.gif

Sounds like a load of useful fun!  Let me know if this sound ok and I'll
make it so!  I can send you a sample scope data file (CSV?) to insure that
it reads ok at your end.

BTW - How much of a ground plane is needed?  I am thinking of putting it on
top of a shelf about 5 by 3 feet with very near by walls and roof.  I could
do the split aluminum foil thing.

Cheer's

	Terry