Great design, Dr. Peters. =20

A question, though.  The web page mentions a feedback system to increase th=
e period.  What would such a system look like?

- Mike



> Date: Thu, 14 Feb 2008 13:56:00 -0500
> From: PETERS_RD@..........
> Subject: new style vertical seismometer
> To: psn-l@..............
>=20
> Those of you who like to build things might want to try your hand at a ne=
w design for the old
> LaCoste spring vertical seismometer.  Internal friction that limits perfo=
rmance has with
> previous designs been mainly concentrated in both (i) spring, and (ii) ax=
is.  My design can
> radically reduce the hinge force influence, which should improve performa=
nce. A prototype is
> pictured at  http://physics.mercer.edu/hpage/new-z.html
>      The key to the smaller reaction forces at the hinge (pair of ball-po=
int pens) is to add an angled
> boom appendage that allows the zero-length spring itself to be vertical, =
as opposced to the usual
> orientation (inclined)--and to place the inertial masses such that the ce=
nter of mass is close to where the
> spring passes through the split region of the horizontal segment of the b=
oom.
>     Although the prototype is shown with an SDC array to sense displaceme=
nt, the instrument can be
> configured to operate with a magnet/coil (Faraday-law) velocity sensor.
>=20
>     Randall
>=20




Great design, Dr=
.. Peters.  

A question, though.  The web page mentions a f=
eedback system to increase the period.  What would such a system look =
like?

- Mike



> Date:=
 Thu, 14 Feb 2008 13:56:00 -0500
> From: PETERS_RD@..........
>=
 Subject: new style vertical seismometer
> To: psn-l@..............> 
> Those of you who like to build things might want to try you=
r hand at a new design for the old
> LaCoste spring vertical seismome=
ter.  Internal friction that limits performance has with
> previous d=
esigns been mainly concentrated in both (i) spring, and (ii) axis.  My desi=
gn can
> radically reduce the hinge force influence, which should imp=
rove performance. A prototype is
> pictured at  http://physics.mercer=
..edu/hpage/new-z.html
>      The key to the smaller reaction forces a=
t the hinge (pair of ball-point pens) is to add an angled
> boom appe=
ndage that allows the zero-length spring itself to be vertical, as opposced=
 to the usual
> orientation (inclined)--and to place the inertial mas=
ses such that the center of mass is close to where the
> spring passe=
s through the split region of the horizontal segment of the boom.
>  =
   Although the prototype is shown with an SDC array to sense displacement,=
 the instrument can be
> configured to operate with a magnet/coil (Fa=
raday-law) velocity sensor.
> 
>     Randall
> 

=