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Entry  Wed Apr 21 15:21:52 2010, Tara Chalermsongsak, Electronics, , TF of PDH Box 2010_04_20_bode_com.png
    Reply  Wed Apr 21 15:39:46 2010, rana, Electronics, , TF of PDH Box 
Message ID: 110     Entry time: Wed Apr 21 15:21:52 2010     Reply to this: 111
Author: Tara Chalermsongsak 
Type: Electronics 
Category:  
Subject: TF of PDH Box 

I calculated the TF of the modified PDH box and fit it with the measurement. The comparison does not match perfectly. I'll take a look and check if all Rs and Cs in the circuit are actually the same as those in the box.

 

The circuit can be found at:

https://dcc.ligo.org/DocDB/0003/D0901351/002/pdh_b_v2.pdf

I checked only U7 and U4

R28 is 360 ohms

C18 is 3300 pF

C6 is 0.66 (2x0.33uF) uF

R30,R31, R23,R16,R24 have the same resistance as specified

C20,C28, C29, C14,C15, R25, C11 are removed.

 The calculation assumes that the integrator switch is off (R16 is connected parallel to R24 and C6)

If this works, the TF for PDH will be used in the simulink model.

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