PSN-L Email List Message

Subject: Re: two-stage Roberts circuit amplifier
From: "Geoffrey" gmvoeth@...........
Date: Mon, 28 Dec 2009 01:27:56 -0700

Below resonance at 1Hz for a SPZ Velocity device
I recommend no more than 6Dbv per octave (20 per decade)
because if you go 40 you get terrible microseismic

So like you give X1250 for everything in a 12 bit system
and + 20 Dbv per decade below 1Hz at 20log(vout/vin)

So its like X1250 * 10 or x12500 or 20log(12500) overall
with a one stage LPF at 0.1 Hz.
But only if you use a 12 bit converter
with a range of 0 to 4.095 volts.
And a sensor of 2.99 volts per inches per second

Or so it seems to me based on a lot of playing around.
Your sensor here is 1 second free period but the idea is universal.

Its interesting to note here you are
simply using a generator to act as a receiving
antenna for earthly vibrations.
Just imagine the terawatts of oil disappearing
into the ground with the incessant human activities.
Dissapating as entropy and lost literally forever
to the depths of space and time.
Stand aside Professor CoupDegrass , here i come !


----- Original Message ----- 
From: "Barry Lotz" 
Sent: Sunday, December 27, 2009 5:42 PM
Subject: two-stage Roberts circuit amplifier

I found the abstract and filter diagram on John Lahr's web site. 1) I am not sure how the max gain is chosen. Is it based on the 
difference between the actual sensor low frequency corner and the desired low frequency corner given a 40 db /decade dropoff? 2) I 
assume the two single pole circuits identical 3) Do the other values in the example circuit remain the same except as you have 
commented on? 4) If I want a lower corner frequency of 0.03 hz is the "lower turnover frequency (1/2 Pi C1 R2)" = 0.015 hz? It is 
probably obvious I don't have the full report.



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