John,
What are you using for a spring?  Is it a special magic "zero length"
spring
or just something from the hardware store?

Thanks,
Jack

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@...............
On Behalf Of John or Jan Lahr
Sent: Friday, February 17, 2006 6:08 PM
To: psn-l@..............
Subject: Re: Geophones on ebay

It's not that hard to make a short period sensor with a period of=20
about 1 second.  I've event been experimenting with one made mostly=20
of wood!  I've posted pictures here:
http://jclahr.com/science/psn/wooden/
The period is just over 3 seconds, but at 1 second period it would be=20
even more stable under
changed in temperature.

I actually like the toy store idea and think it would be easy to mass=20
produce a very inexpensive
system.

Cheers,
John

At 09:59 AM 2/17/2006, you wrote:
>I have to say that such a 1 sec geophone new
>will cost you in the neighborhood of
>$3000 USD so I think people who buy them
>are not too eager to give them up
>at a reduced price. I think those
>geophone people would be doing all us
>amateures a favor to create a lesser quality
>device at 1/10 the cost.
>Maybe if the chinese were to make them
>they could make them cheaper and sell
>them at Walmart in the toy section for the
>Jimmy Neutrons of this Earth.
>gmvoeth
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