PSN-L Email List Message
Subject: Re: Simple broadband Seismometer
From: Gordon Couger gcouger@..........
Date: Fri, 02 Sep 2005 03:16:38 -0500
I am late to the discussion so I have missed things. Are you
using the principle of to cans with largo areas connect together
by a tube with a very small diameter bore and an air bubble
introduced into the bore will amplify the change in levels in
one can related to the other and the change in the position of
the bubble depends on the are of the can to the area of the tube
Fantastic amplification is possible with very simple tools. The
surface of the bubble blocks nearly 100 % of the light shined
on it so photocells or rotating photo paper can easily track the
> In a message dated 01/09/2005, ian@........... writes:
> one assumption I made was that the mean signal, generated
> mean mass is subtracted and you are then only measuring the
> changes. If some piezo sensor can withstand a load
generated by 44
> Kg (2 supports), then 2 of them might give the required
> electrically differencing the signals from the 2 piezo
> remainder is the changing mass + noise. Just a thought...
> Hi Ian,
> I don't really see why you need such a large pipe, when
> nearer 1" would do fine. If you put on larger diameter end
> increase the period.
> Trying to match up two sensors allowing for temperature
> and drifts just doesn't work to better than about 0.1%.
> When it is dead easy to measure water levels to microns,
> with weight sensors? The inexpensive piezo sensors drift in
> voltage with temperature.
> There re plenty of problems in making precision
> things the hard way' is just plain dumb.
> Chris Chapman
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