PSN-L Email List Message

Subject: Re: Volksmeter sensor and the AD774x CDC chip
From: ChrisAtUpw@.......
Date: Tue, 18 Apr 2006 19:07:32 EDT


 
In a message dated 18/04/2006, lcochrane@.............. writes:

The  discussion last week about the AD7745/6 chip was rather timely. The 
event  files that I have been posting on the event file archive system with the 
file  extension of *.LCTST.PSN are from the new Volksmeter sensor. If you 
compare  the LC8 channel of my S-G sensor and the new Volksmeter sensor you will see 
 they are similar since they both use a short period pendulum and a  
displacement pickup.



Hi Larry,
 
    What period compensation are you claiming for this  sensor? 
    Do the plots show a compensated velocity /  compensated displacement / 
uncompensated signal, or what?
    How are you performing the velocity feedback /  damping necessary to 
stabilise the response?
 
    I note that in your SG EMail reference, you claim a  flat response from 
50 sec to 3 Hz, but remarked that you had to substantially  increase the 
damping to get this. I note that in your latest circuit diagram,  you seem to have 
greatly reduced the itegration time and wondered if the circuit  values were 
correct? 
 
    Regards,
 
    Chris Chapman





In a message dated 18/04/2006, lcochrane@.............. writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>The=20 discussion last week about the AD7745/6 chip was rather timely. The event=20 files that I have been posting on the event file archive system with the f= ile=20 extension of *.LCTST.PSN are from the new Volksmeter sensor. If you compar= e=20 the LC8 channel of my S-G sensor and the new Volksmeter sensor you will se= e=20 they are similar since they both use a short period pendulum and a=20 displacement pickup.
Hi Larry,
 
    What period compensation are you claiming for t= his=20 sensor?
    Do the plots show a compensated velocity /=20 compensated displacement / uncompensated signal, or what?
    How are you performing the velocity feedback /=20 damping necessary to stabilise the response?
 
    I note that in your SG EMail reference, you cla= im a=20 flat response from 50 sec to 3 Hz, but remarked that you had to substantiall= y=20 increase the damping to get this. I note that in your latest circuit diagram= ,=20 you seem to have greatly reduced the itegration time and wondered if the cir= cuit=20 values were correct?
 
    Regards,
 
    Chris Chapman

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