Mercury is incredibly dangerous
and just how much mercury are you talking ?

It is an insidious poison like most other
heavy metals which the human body has
no use for. It will rob you of motor function
and lower your IQ.

If you like the girls I would not play with mercury
you will not dance so good anymore.


----- Original Message ----- 
From: "Pete Rowe" 
To: 
Sent: Saturday, September 15, 2007 7:48 AM
Subject: Re: Tiltmeter as Horizontal Seismometer


> Hi again Chuck
> I left out one important piece of the circuit. Chris'
> reply to you jogged my memory. Since you drive the
> bridge with AC, you have to have a synchronous
> rectifier after the gain stages to turn the signal
> back to DC. This is done with an analog switch and an
> op amp. Easy.
> As Chris mentioned, the homemade liquid filled tube
> may be your best bet for building the sensor yourself.
> I saw one of these at Cal Tech many years ago. It was
> about 2 meters long and had a horizontal tube filled
> with Mercury. They sensed the level of the Mercury in
> a cup at each end capacitively. With today's
> capacitive sensor ICs, this should be easy to do.
> Good luck!
> Pete  
> --- Chuck Burch  wrote:
> 
>> 
>> I am drafting plans to build a three electrode
>> spirit level style tiltmeter to use as a 
>> horizontal seismometer.  Any hints on construction? 
>> What liquid is best?  Are 
>> surface tension and/or viscosity critical?  
>> 
>> I'm planning on using a Wheatstone bridge detector
>> circuit.  Can this be improved?
>> 
>> Thanks for your comments.
>> 
>> Chuck I. Burch
>> 
>>
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