AS-1 Damping Adjustment

The images below show how a lift-test calibration of an AS-1 instrument changes as the damping is adjusted.  In order to determine the damping ratio, I simultaneously recorded the output of the AS-1 coil with the AS-1 black box amplifier and AmaSeis as well as with a 1000x gain amplifier attached to a DATAQ 158UP ADC and recorded with WinDaq.  To reduce the high-frequency noise that is picked up by the AS-1 coil, an 80uF capacitor was connected in parallel with the coil.

Chris Chapman has designed an amplifier circuit for this purpose.

AS-1 Amplifier & AmaSeis

First Peak

DATAQ 158UP & WinDaq

A1/A2 Damping Ratio*

200609062248cal.sac
-1253
cal014.sac
870/35 = 25 0.71 Best

200609052357cal.sac
-1621
cal003.sac
1229/110 = 11 0.61

200609060014cal.sac
-1628
cal005.sac
1244/192 = 6.5 0.51

200609060018cal.sac
-1666
cal006.sac
1509/455 = 3.3 0.36

200609060022cal.sac
-1716
cal007.sac

1464/702 = 2.1

0.23

200609061921cal.sac
-2024
cal011.sac

1824/1349 = 1.4

0.10

*Damping ratio computed using this page:  http://www.jclahr.com/science/psn/damping/


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