How exactly is the LTC1043 used? Are we sensing capacitance change in
distance or resistance change in fluid depth? I need more information.
The mercury tiltlevel sensor is well known but it works because mercury
is a cohesive, not an adhesive liquid. Help me out here, this sounds
really interesting.
=20
John Nelson
=20
________________________________
From: psn-l-request@.............. [mailto:psn-l-request@...............
On Behalf Of ChrisAtUpw@.......
Sent: Sunday, August 28, 2005 8:27 PM
To: psn-l@..............
Subject: Re: Simple broadband Seismometer
=20
In a message dated 28/08/05, paleoartifact@......... writes:=20
Subj:Re: Simple broadband Seismometer=20
From: paleoartifact@......... (meredith lamb)=20
Congratulations Dave! Amazing perseverance and effort went into this!=20
On the surface; it sounds like this specific MET, it could well make all
the various designs of older horizontal mechanisms and sensors rather
obsolete. =20
It seems that the LTC1043 is more available in european/asia areas.
Would be interested in any possible U.S.A., distributors (and rough
price)
See www.digikey.com LTC1043CN-ND
18 pin DIP at US $5.13=20
Jeff Witt has a good bridge circuit using the LTC1043. See
www.linear.com wrote:=20
I have been intrigued by the concept of using a liquid as the seismic
mass in a broadband instrument for some time. The original thought came
the idea that a damping plate was being moved through a liquid -- why
not move the liquid through the damping plate. I have also studied the
MET seismometer (I operate a CME MET vertical seismometer in my home
system) and have a moderate understanding of its principals and the
electrochemistry involved.
I prefer the telephone for detail discussion as I am not a good typist.
I am from the old school where a secretary did the typing so I am bit
slow on the keyboard.
I will let you into two secrets! You can get programs to teach you
to type! It took me about a week to get reasonably proficient.=20
You can also get programs which take a microphone input and give
you a printed word output....=20
Regards,=20
Chris Chapman
How exactly is the LTC1043 used? =
Are we
sensing capacitance change in distance or resistance change in fluid =
depth? I
need more information. The mercury tiltlevel sensor is well known =
but it works
because mercury is a cohesive, not an adhesive liquid. Help me out =
here, this
sounds really interesting.
John =
Nelson
From:
psn-l-request@.............. [mailto:psn-l-request@............... =
On Behalf Of =
ChrisAtUpw@.......
Sent: Sunday, August 28, =
2005 8:27
PM
To: =
psn-l@..............
Subject: Re: Simple =
broadband
Seismometer
In a message dated 28/08/05, paleoartifact@......... =
writes:
Subj:Re: Simple =
broadband
Seismometer
From: paleoartifact@......... (meredith lamb)
Congratulations Dave! Amazing perseverance and effort went into =
this!
On the surface; it sounds like this specific MET, it could well make all =
the
various designs of older horizontal mechanisms and sensors rather =
obsolete.
It seems that the LTC1043 is more available in european/asia areas. =
Would
be interested in any possible U.S.A.
See =
www.digikey.com LTC1043CN-ND
18 pin DIP at US $5.13
Jeff Witt has a good bridge circuit using the LTC1043. =
See www.linear.com Application Note AN87 =
p87
While you can get Platinum wire and =
foil
and also gold for making electrodes, they are expensive. Have you tried =
making
the electrodes out of graphite? You can get single crystal graphite =
sheet. The
central electrode rods from dry batteries are another convenient source. =
Battery electrodes usually come with a crimped =
brass cap.
You can get silver and copper metallic paints to make a bond with =
graphite
sheet. You can also use conical electrodes.
Needle valves can give very non linear flow =
characteristics
with differing flow rates. A more linear variable restriction may be =
obtained
by squeezing flexible tubing (silicone rubber?) in between two flat =
strips of
metal or plywood.
I have used this to provide very =
tiny leak
rates by putting a wire down the centre of the tube before it is =
clamped. You
could also use thin nylon rod or monofilament to give a non conducting =
core.
The fluid sees two tiny triangular tubes between the sides of the wire =
and the
two tube surfaces.
Nicolas d'Oreye http://edoc.bib.ucl.ac.be:81/ETD-db/collection/availa=
ble/BelnUcetd-10172003-155611/
describes the flow and period calculations fairly fully in his thesis, =
although
he applies it to a precision water tiltmeter. It is in French, so you =
may need
http://babelfish.altavista.com/
On the subject of reducing the =
effects of
surface tension, it should be possible to fit a very thin rubber =
membrane over
the ends of the tube when using a capacitative detector --> no free =
surface.
This would certainly be worth trying.
I prefer capacitative sensing for =
measuring
the height of water columns. The dielectric constant of water is about =
80. Oil
is usually about 2. This enables you to use high purity water which =
greatly
reduces corrosion problems. You can use marine varnish to protect metal
surfaces.
On 8/28/05, =
Dave Nelson <davefnelson@.......> wrote: =
I have been =
intrigued by
the concept of using a liquid as the seismic mass in a broadband =
instrument for
some time. The original thought came the idea that a damping plate was =
being
moved through a liquid -- why not move the liquid through the damping =
plate. I
have also studied the MET seismometer (I operate a CME MET vertical =
seismometer
in my home system) and have a moderate understanding of its principals =
and the
electrochemistry involved.
I prefer the =
telephone
for detail discussion as I am not a good typist. I am from the old =
school where
a secretary did the typing so I am bit slow on the =
keyboard.
I will let you into two secrets! You =
can
get programs to teach you to type! It took me about a week to get =
reasonably
proficient.
You can also get programs which take =
a
microphone input and give you a printed word output....
Regards,
Chris =
Chapman