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<font face="Arial">re_previous 'problem' report:<br>
Further testing confirmed problem due to voltage sag at end of
CAT5 cable; in retrospect, a 'classic' example .... oops.<br>
<br>
I did not take time to measure dropout voltage on this unit before
installation as I did on the first board used in a weather proof
above ground box install. Changing to an SPX1117M3-L-3-3 LDO
regulator with 250mV additional dropout margin as well as larger
filter caps.<br>
<br>
From a voltage drop viewpoint, 400 feet of CAT5 or CAT6 24Ga solid
copper wire and a well regulated 5 volt supply for the
microcomputer represents about the practical limit in cable
length. Standard i2c signalling rate of 100KHz presents no
problem at that length.<br>
<br>
Jules Madey K2KGJ<br>
<br>
</font>
<div class="moz-cite-prefix">On 8/12/2020 3:14 PM, David Witten
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CABJ3BVNWVvWBjUXcPn1BVjvdsY7e_15-uU1WNU5KY8tXhes8uA@mail.gmail.com">
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<div dir="ltr">Jules,
<div><br>
</div>
<div>Very interesting! </div>
<div><br>
</div>
<div>I'm curious what effect we might see burying the sensor
completely, say below the frostline:</div>
<div><br>
</div>
<div><a href="https://www.hammerpedia.com/frost-line-map/"
moz-do-not-send="true">Frostline Map</a><br>
</div>
<div><br>
</div>
<div>This would make deployment more difficult, but would surely
provide significant stability. </div>
<div><br>
</div>
<div>But what does it do to magnetic field lines? - one more
experiment that I would like to try sometime: place several
sensors in a vertical column at, say 500 cm intervals in a
fairly uniform deposit of soil.</div>
<div><br>
</div>
<div>Seismic interaction is something I hadn't considered.</div>
<div><br>
</div>
<div>Dave</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Aug 12, 2020 at 1:21
PM Julius Madey <<a href="mailto:hillfox@fairpoint.net"
moz-do-not-send="true">hillfox@fairpoint.net</a>> wrote:<br>
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0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div> <font face="Arial">Dave, <br>
Did a 13 hour run from 2300edt yesterday to noon today and
then started a second run to complete 24 hours. Seeing a
slight 0.3 degree upward shift in temp over the 13 hours.
The sensor results are not flat line and still show some
drift with an initial relatively rapid change after
starting the run ... have to see if the same thing happens
on the run in progress now. <br>
Some activity around 0400edt to 0900edt which I can't
explain as magnetic field shifts, at least according to
the data from Intermag. Might be seismic activity related
as any movement of the sensor could also create a 'signal'
in the low nT range (~50nT).<br>
Jules<br>
<br>
</font><br>
<div>On 8/12/2020 10:26 AM, David Witten wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Jules,
<div><br>
</div>
<div>I will look closely at this when I get back from my
appointment this am. THere are definitely some
untested 'features' here. </div>
<div><br>
</div>
<div>Dave</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Aug 11, 2020
at 9:49 PM Julius Madey <<a
href="mailto:hillfox@fairpoint.net" target="_blank"
moz-do-not-send="true">hillfox@fairpoint.net</a>>
wrote:<br>
</div>
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0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div> <font face="Arial">Dave, <br>
I think we're OK operator error here with
parameter formats .... <br>
Sorry for the false alarm<br>
Jules<br>
<br>
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