George,
Could you tell me more about the advantages of a triangular shape for the spring
as opposed as a retangular shape.  Also I would like more info on heat treating
the berrylium copper.

Jim Hannon




George Harris  on 10/21/99 07:19:13 PM

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Subject:  Re: Strong motion sensor design





The most efficient simple spring system is a flat spring having a triangular
shape.
That is, the mass is attached to one point of the spring which is clamped along
the
opposite side.  Having a voice coil driver and an optical pickup on the mass
would
seem to make a simple rugged feedback system.  If low frequencies are to be
sensed,
the deflection should be as much as possible to make the resonant frequency low
so
that the sensor does not need as much gain.  The feedback corner frequency must
be
well above the natural frequency to make the feedback system simple.

I have worked with berrylium copper springs.  An ideal way to make them is to
form
the spring in the soft state.  Hardening is then done by heating to about 600
degrees F. for an extended period.  This process makes about the best springs
which
can be fabricated.  An etched spring can be made by drawing the shape with the
resist pen used for printed circuits on one side and applying a sheet of
adhesive
resist on the back.

I would be glad to work with anyone in the bay area to see if we can come up
with a
simple construction.

George Harris - Benicia, CA - gjharris@.............







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