PSN-L Email List Message

Subject: Re: HS-10 manual
From: Brett Nordgren Brett3mr@.............
Date: Mon, 03 Dec 2007 10:51:00 -0500


Sorry to hear about your HS-10 problem.

However, I was also interested in your VBB project.  Had you ever 
considered using a feedback system to stabilize the mass position?  It's 
not a trivial undertaking, but once working, it might help a lot.

Where can I see a description of the Blumelein Bridge?  Capacitive sensors 
have always seemed like a good approach to me, and I'm interested in 
learning about as many designs as I can.

Good luck with your project.


At 11:05 PM 12/2/2007 +0100, you wrote:
>thank you very much for doing this test! Your findings confirm my decision
>to (try) to return
>it to the dealer. He is on holidays now, so communication is somewhat slow.
>He has a second HS-10, maybe he will test this one with the simpler 100 k
>resistor test for
>linearity. But I expect a similar result..
>Maybe I should reactivate my VBB project instead. I tried to reproduce a
>very compact
>VBB design (inv. pendulum) from a scientific journal with a small mass
>(~50g) and blumelein bridge  capacitive
>displacement sensor. It worked quite well for the small size. I could see
>the 6s microseisms clearly and
>a ~6 quake in Papua NG. But I had some mass drift problems and lost my
>interest in it.
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