Dick Webb wrote:
> 
> Hi,
> 
> Recently, I obtained two HS-10 seismometers that are of the bore hole
> variety.  They are vertical and I am interested in converting them to
> horizontals.  Can this be done and if so how.
> 

Are you sure they are verticals?  It is common to find two horizontals
and a vertical in a borehole geophone.

Anyway, the difference between them is the springs that hold the mass
centered.  Vertical geophones springs have to hold up the mass against
gravity.  It is not likely that you could take one apart, change it, and
put it back together.  However, you might be able to bias the geophone
by putting a little DC current into the coil, then AC coupling it to the
amplifier.  Sort of an electrical spring.  Use a resistor large enough
to not over-damp the geophone.

Feels a little klutzy, but what are we for if not to try innovation
solutions.

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