I agree with both John and Jan that a strong motion sensor 
should be an add-on to a high gain system (either long or short period
depending on the local seismicity).  The 
schools will primarily use the high gain data, but since a recording system
is already in place, you can add strong motion for much less cost
than at a new installation.

Larry wrote:
>What is missing is a good simple design for a SM type
>sensor. Also, to be used as a teaching device it should be rather large
>(like the size of a geophone) with a clear case.

I'd be more inclined to work towards a design that was concerned most 
with low cost and an acceptable noise level, than considering its
teaching potential because the seismometer can be used for that.

I'd also agree that it would be better to have the frequency response
extend to 25 Hz.  I think you could get away with a low end of 0.1 Hz
for most free field sites.

Regards,

John Taber



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