> Subject: Re: Honduras Quake / geophones
> From:    ChrisAtUpw@.......
> Date:    Fri, 29 May 2009 14:33:09 EDT

>     If you simply change your technology to Piezo  sensors 102-1170-ND @
> US
> $1.62 instead of 4.5 Hz geophones, you can do this  fairly easily. You do
> need to make a suitable FET input amplifier; the  piezo disk needs to be
> kept
> dry and at a fairly stable temperature. I use a  honey jar with a metal
> lid, a moulded rubber seal and a sachet of silica gel. I  stick a PCB disk
> with
> soldered electrical feed through pins over a  hole in the lid, using two
> part acrylic adhesive. The amplifier is mounted  inside the lid of the
> jar, to
> keep it dry. The input impedance is about 50 M  Ohms.

Hi Chris

Sounds interesting in theory, but how well does it actually work?

Do you have any data/spectra from your piezo device that shows it
picks up teleseismic events as well as a my horizontal 4.5 Hz geophone?

Dave


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