I saw a web page at one time where a guy had made a similar sensor by
adding weight to a loadspeaker cone. Any external vibration moved the
speaker & the cone inertia generated  a few mV of signal.
Use as large a speaker as is available.

RP

On 09/05/06, Mark E. Skeels <meskeels@earthlink.net> wrote:
> Thanks to all who responded. As usual, the PICList is a wonderful source
> of information. Where else can you tap into a knowledge base of 2000+
> engineers, technicians and scientists?
>
> I think this is not an earthquake, but blasting of some kind nearby. So,
> I'm not sure that what I need is a seismometer, exactly. It shakes the
> house, so I thought to attach the device to the wall of my second story
> bedroom.
> The three foot mechanical pendulum might work, but I need something that
> will log the disturbance. We won't be standing there when it occurs.
>
> So I'm still thinking my best option is the accelerometers. I found some
> nice pcb assys' on Sparkfun electronics site:
>
> http://www.sparkfun.com/commerce/categories.php?cPath=23_80
>
> I'm on vacation next week, so it will be a while before I get to this.
>
> Thanks again,
> Mark
>
>
> Jinx wrote:
>
> >The September 05 issue of Silicon Chip has a Build Your
> >Own Seismograph project
> >
> >Full article is not available on-line but I can supply details
> >if you're interested
> >
> >http://www.siliconchip.com.au/cms/A_105119/article.html
> >
> >The detector is an opto-sensor on the end of a magnetically
> >damped horizontal pendulaum
> >
> >A link in the article to the author
> >
> >http://science.uniserve.edu.au/school/Seismograph/
> >
> >
> >
> >
> >
>
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