(I combined your two posts into one)
Mike
The RV Jones papers were published in either the Review of
Scientific instruments or the Journal of Sceintific Instruments -
I forget which.
I'll look for my paper copies when I get back from shopping later
today.
Mike
One good general reference for capacitance micrometers is:
/Microdisplacement Transducers/ by P.H. Sydenham, Journal of Physics E,
Scientific Instruments, Vol 5, p721-33, 1972.
Mike Monett wrote:
Hi Bruce,
Thanks for the info. I looked at Physik Instrumente, and their
performance is truly impressive. For example, the D-510.020
single-electrode capacitive sensor has a nominal range of 20 um, and
a sensor active area of 11.2 mm^2:
Bruce Griffiths [EMAIL PROTECTED] wrote:
Mike
One good general reference for capacitance micrometers is:
/Microdisplacement Transducers/ by P.H. Sydenham, Journal of
Physics E, Scientific Instruments, Vol 5, p721-33, 1972.
Mike Monett wrote:
Hi Bruce,
Thanks very much for the url. That is a very interesting article on
Jones. Nice to have an award named after you, and to be the first
one to receive it:)
The abstract for his article states:
A general account is given of both the
Bruce,
A totally trivial correction for you :
the work of RV Jones at the university of Glasgow in the 50's, 60's and
70's.
Jones was at Aberdeen university post war. A curious character, his
recollections of his wartime research are fascinating and worth reading but
I fear are best read with
David wrote:
Bruce,
A totally trivial correction for you :
the work of RV Jones at the university of Glasgow in the 50's, 60's and
70's.
Jones was at Aberdeen university post war. A curious character, his
recollections of his wartime research are fascinating and worth reading but
I fear
Hej Bruce,
Hej Magnus
A capacitive sensing AC bridge can be very sensitive, one only has to
look at the work of RV Jones at the university of Glasgow in the 50's,
60's and 70's. He and his collaborators used capacitive sensors to
detect (among other things) the extrusion of a micrometer
Hej Magnus
An elegant way of achieving some degree of temperature compensation may
be to use 3 coaxial electrodes surrounding the mercury column.
One relatively long one used to couple the bridge drive signal to the
mercury column and located between the other 2. The top electrode one
being
Bruce, very interesting. I didn't know capacitive sensors went down
that low. That could be useful in other areas.
I searched google but found nothing. Do you have any urls?
http://www.eetimes.com/showArticle.jhtml?articleID=175801455
EE Times: SENSORS: Quake detector preps for
Bruce Griffiths [EMAIL PROTECTED] wrote:
Mike
The drifts experienced were all due to mechanical instabilities
which would affect an interferometer sensing the position of the
sensor mass in exactly the same way.
Jones used mica insulators, phosphor bronze and brass to
Bruce Griffiths [EMAIL PROTECTED] wrote:
Magnus Danielson wrote:
Hej Bruce,
[...]
Indeed. However, I was trying to hint on a alternative approach
or temporary approach which would not need much design to achieve
equal performance if the electrodes could not be
Mike Monett [EMAIL PROTECTED] wrote:
[...]
Gentlemen,
The problem is very simple. If the sensor lead that contacts the
mercury has a diameter of 0.010 inch, with a flat end, and is 100
microinches away from the mercury, the capacitance is 0.35 pf.
Sorry, I used a bad
Magnus Danielson wrote:
My proposal to use capacitive sensing rather than conductive sensing
would handle the electrode oxide issue. It is meant as a means to go
around the sensing issue with parts at hand and only some new electronic
design of very simple form, not the means to
Bruce Griffiths [EMAIL PROTECTED] wrote:
Hej Magnus
A capacitive sensing AC bridge can be very sensitive, one only has
to look at the work of RV Jones at the university of Glasgow in
the 50's, 60's and 70's. He and his collaborators used capacitive
sensors to detect (among
Mike Monett wrote:
Bruce, very interesting. I didn't know capacitive sensors went down
that low. That could be useful in other areas.
I searched google but found nothing. Do you have any urls?
Regards,
Mike Monett
Mike
The RV Jones papers were published in either the
Mike
You could also look at Queensgate Instruments.
Integral capacitive sensors have been used in a feedback loop to
maintain the spacing and parallelism of a pair of Fabry-Perot
interferometer plates.
Bruce
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