TSSP: List Archives

From: "Terrell W. Fritz"
Date: Thu, 28 Mar 2002 17:07:02 -0700
Subject: Re: Ready :-)) - Re: [TSSP] short H/D and stuff

Hi Paul,

At 08:25 AM 3/28/2002 +0000, you wrote:
>
>> Let's see:
>> 22nF and 32.65mH resonates at 5936Hz so that's not it.
>
>I was thinking of the current loop involving the 22nF and the
>Victoreen, but looking at it, there's not much room to get the
>necessary inductance.  Then again, it could just be an artifact
>of the software!  Time will tell - it will either go away or
>become more prominent.

The long ground wire may be acting as an inductance and resonating with the
22nF cap.  Hard to measure or figure out.  There are lots of stray reactive
elements if one goes looking. 

>
>> I am no expert on the Sun UNIX stuff but I think I can
>> figure out the compiling and stuff.
>
>Do you know whether the GNU C compiler is installed, or the native
>Sun?  If in doubt, type gcc to the dollar prompt and see what
>happens.  We really should be doing something with that machine.
>Is it possible to reach it from the Internet with telnet and ftp?

Gcc is certainly available for Sun (solaris) along with probably all the
other UNIX toys:

http://www.sunfreeware.com/

It is connected to the net but I just have to figure how to turn all the
FTP and telnet stuff on.  I got it to learn more about "good" computers but
I am still real green on all that stuff ;-)  I need to move it this
weekend.  Maybe to the playroom.  Having three PCs on one desk is a little
too much!

>
>> http://www.metratek.com/
>>  I always like "little guy" programmers like that
>

I ordered up that software.  Looks like a real nice addition to my new
RS-232 card :-)

>
>First off, to prove that things are working, we should be able to
>observe a Q variation of the order of 0.4% per deg C resulting from
>the increase of copper's R with T.  Whether we see greater or lesser
>change in the Q with temperature will depend on what fraction of the
>total loss the copper loss accounts for, and on the temp coeff of
>other the lossy materials in the system.

Neat!  Almost make a good thermometer.  Perhaps the worlds most complex
thermometer :-))

>
>For this test, we should try to exclude as many other sources of
>loss as possible, so a foil groundplane and faraday cage to
>contain the E field would be nice.  Completely enclosing the coil
>in a foil cylinder would do the trick, and the resulting eddy
>currents will have the added bonus of containing most of the B field
>too.  By this means we ought to be able to obtain a baseline Q
>variation due to the coil materials alone.  Then work forwards by
>introducing each bit of the environment separately.
>
>The other approach would be to just put the coil out there and get
>a look at the full variation, then work backwards to isolate or
>eliminate each possible contribution.

Probably just get the thing going first and iron out any problems.  Then we
can do anything we want :-))

>
>I'm just wondering whether it would be possible to ping several
>coils all at once, ie bases all converge to a junction at the
>coil side of the Pearson.  The trace records several overlapping
>ringdown waveforms, and tcma untangles it all.  If you want to
>try this - ping two coils separately, then ping them both together
>and we'll see how the three CSV files compare.  If the coils are
>far enough apart, the virtual ground through the spark gap should
>ensure the coils are decoupled from each other.   Would be a good
>way to compare sonotube and plastic formers.  tcma uses +/- 3%
>bandwidth to separate the frequency components, so the coil's
>Fres need to be more than 6% apart if high Q, and further apart
>if low Q (because the faster ringdown has a higher bandwidth, so
>the ringdown from one component spills over into the bandpass of
>the other, hindering convergence).

I wonder if the coils will couple to each other?  No matter, it is easy to try.

>Terry, will you be moving the coil images and CSV data to a more
>permanent directory on hot-streamer.com?  If so, I can deep link
>to them.  The quality of these experiments is such that they
>deserve a decent write up.

Ok,  I'll just make a directory that will appear as:

http://hot-streamer.com/tssp/

And put stuff there permanently.  Feel totally free to grab any data too if
you want to put it up on your site.  I am sort of an anti-copyright kind of
guy :-))

>Marco wrote:
>> Precisely, how this new measurement of a coil Q is practically
>> conducted (setup, jumpers, etc.)?
>
>I think we'll have to defer thorough explanation to a web page.
>Terry, are you thinking of doing a write-up?

See:

http://hot-streamer.com/temp/Paul/3-24/PingDiag.jpg

http://hot-streamer.com/temp/Paul/3-24/PingSchem.jpg

http://hot-streamer.com/temp/Paul/

I have the new pinger designed.  I'll try to get the schematics and such
posted ASAP.

>I've been comparing the single-shot 3-24 and average-16 
>traces 3-26 and with the latest version of tcma there is 
>a clear difference emerging:
>
>        single-shot    average-16
>f1/4     0.4%             0.2% 
>f3/4     4%               1%
>f5/4     20%              8%
>
>So there is now a distinct advantage to averaging over at least
>16 pings.
>
>Perhaps we should compare some 16-ping traces to some 64-ping?

The traces do seem to clean up quite a bit so I am not surprised accuracy
is helped.  I'll grab the same wave at a bunch of different settings and we
can decide which we like the best.

>
>I'm quite keen to see if two coils can be pinged together in
>one trace, if you want to try that?

No problem there.  I'll give it a try.

Cheers,

	Terry






Maintainer Paul Nicholson, paul@abelian.demon.co.uk.