PSN-L Email List Message

Subject: Re: those strange jumps
From: "Al Allworth" allworth@..............
Date: Tue, 25 Jul 2000 18:27:26 -0700

A suggestion on shielding the coil with foil:
Make sure the foil doesn't make a shorted turn around the coil. This would
cause serious problems and poor sensitivity.

                     Al  Allworth

On the Beautiful Southern Oregon Coast

----- Original Message -----
From: "Bob Smith" 
Sent: Tuesday, July 25, 2000 2:11 PM
Subject: Re: those strange jumps

> John --
> One additional thought, The time that a radio station "signs
> off" does not necessarily coincide with the time that they
> drop carrier (shut down the transmitter), same on start up
> in the morning.  These periods just after and just before
> the broadcast day are often used for tranmitter adjustments
> and testing.  I suggest a portable A.M. radio to listen for
> carrier outage while you are monitoring.  A strong,
> unmodulated carrier will have a marked "quieting" effect on
> what you hear.
> Best wishes, Bob Smith
> John Tacinelli wrote:
> >
> > HI again,
> >
> > I am overwhelmed with good ideas! Thank you all so much.  I will try do
deal with each.  First of all the line voltage.  I have not checked this,
however since the UPS showed the same problem, I don't think it is the line
voltage.  I called the utility company and they said there were no shifts
related to capacitors at that time.  They said there was a shift in usage
around that time but they couldn't be very specific.  I'm pretty sure its
not a joke, our students are not that bright....  I thought about
streetlights but each is on its own photo cell and so they come on
irregularly.  I did not have the seismograph running during the time change
so I don't know if it tracks.  We are decidedly not in the desert here in
Minnesota so I doubt it is the building heating and cooling, besides, this
is too regular for something like that.
> >
> > I like the idea put forward by Charles and Bob about AM radio
interference.  I called around and there are two radio stations that have
restricted licences.  One goes off the air at 8:45 and back on at 5:45.
Very interesting.  The other station changes power level from 5000 to 1000
watts at about that time.  They couldn't be more specific.  The station that
goes off air says that I could shield the coil with grounded aluminum foil.
So I took the box that I use as an air cover and taped aluminum foil all
over it.  I attached a wire to it with electrical tape and modified a
regular AC 3-prong plug so that only the ground plug was there.  I attached
the wire and plugged it into the  power strip for the computer.  The trace
that had been going more or less down the middle, shifted to the left side
of the screen.  So it seems to be doing something.  Tonight I will watch the
thing again, this time with the shield in place and two radios going.  If it
happens again I'll see if it
> > coincides with the radio sign-off ( or signal decrease).  Also , the
radio station changes its on-off times monthly so I can also see if it
changes at the end of the month.  I am hopeful and will keep you all
informed.  Thanks again for the help.
> >
> > John Tacinelli
> > Earth Science Instructor
> > Rochester Community and Technical College
> >
> > __________________________________________________________
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> --
> ---------  Avoid computer viruses  --  Practice safe hex
> -------------
>  * * Specializing in small, cost effective embedded control
> systems * *
> Robert L. (Bob) Smith Smith Machine Works, Inc.
> internet   bobsmith5@........ 9900 Lumlay Road
> landline   804/745-1065                 Richmond, Virginia
> 23236+1004
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Larry Cochrane <cochrane@..............>