Karl Cunningham wrote:
> 
> When thinking about using loudspeakers for strong motion sensors, don't
> overlook putting a negative impedance converter in parallel with the
> speaker.
> 
> It's a simple circuit with one op-amp and a few resistors that can make the
> speaker into a closed-loop transducer with an acceleration output that can
> be easily integrated to velocity. 

Let's not lose sight of the fact that strong-motion seismographs are
traditionally acceleration recording devices, not velocity sensors like
sensitive seismographs.  If you want to make data accepted by the
establishment, it might go easier if you give them the same information
they are used to.

An acceleration measuring device needs to measure force generated by a
mass pushing on something (think electronic scale, not moving coil).

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