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Entry  Mon Oct 3 13:59:40 2016, awade, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 20161002_D980401_PSLTempBox.epstemp_AD590TransImpedanceBox_PSDs.zipD980400-B.pdf
    Reply  Mon Oct 3 18:15:23 2016, not awade, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 
       Reply  Tue Oct 4 11:49:53 2016, awade, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 20161002_D980401_PSLTempBox_Vrms.eps20161002_D980401_PSLTempBox_Vrms.fig
          Reply  Sun Oct 9 09:01:27 2016, not awade, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 
             Reply  Mon Oct 10 11:32:27 2016, awade, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 20161002_D980401_PSLTempBox.pdf
    Reply  Fri Sep 1 13:36:20 2017, awade, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 
       Reply  Sun Sep 3 14:10:38 2017, awade, Kira, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board LIGO-Temperature-Sense-Board-SingleChannel.pdf
          Reply  Mon Sep 4 23:07:41 2017, Kevin, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board TemperatureSensingCircuit.pdfTemperatureBox.jpg
             Reply  Tue Sep 5 23:54:45 2017, Kevin, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board p1.jpgp2.JPG
          Reply  Wed Sep 6 19:58:21 2017, awade, Kira, DailyProgress, TempCtrl, Modified LIGO temperature sensor interface board 
Message ID: 1730     Entry time: Mon Oct 3 13:59:40 2016     Reply to this: 1732   1889
Author: awade 
Type: DailyProgress 
Category: TempCtrl 
Subject: Modified LIGO temperature sensor interface board 

In a previous implementation of PID control of the vacuum tank temperature, the four AD590 sensors attached to the CNT vacuum tank were configured with a transimpedance amplifiers to produce four voltage signals. These were then fed into 4 separate ADC channels to be averaged in digitally.  

The AD590s take any voltage in the range 4-30 V and produce a current proportional to 1uA/K (where K  is reference to absolute zero).  The current is then converted to a voltage signal with buffering opamps, this is passed to a second (unknown amplification stage) and the voltage output signal is then routed through two Dsub9 connectors to the rack for ADC. 

Typing the PBC board serial number, D980401, into this elog or DCC turned up no results.  However it looks like the board is listed under D980400. It has been modified to make use of only its initial opamp x10 gain stage plus an additional gain stage.  The additional opamps used to provide a tap off of the converted AD590 signals are glued upside down to the PBC board, making it hard to identify what is going on.  Here is what I do know, the board is suppling 11.7 V regulated voltage to each of the two pin AD590s.  Putting a fixed resistance (40.2kΩ) across this voltage source gives a current I = 11.7V/40.2kΩ=2.91uA. At the output of the board we get 2.93±0.01V signal which is 10^4 V/A gain.  

I wasn't sure on the best way to measure the noise contributed by the board. I took the dark noise in two cases, one with no load across the input of the opamp and one with the 40.2 kΩ load (to simulate the expected current for AD590 at room temperature).  I've attached the two PSDs of the output noise (stitched from multiple spans using the SR780). Data and matlab plotting script also zipped and attached.

 

PSD of output voltage noise for terminated and unterminated input of the D980401 Temperature box

Edit: typos Mon Oct 3 14:40:52 2016 awade

Attachment 2: temp_AD590TransImpedanceBox_PSDs.zip  594 kB
Attachment 3: D980400-B.pdf  47 kB  | Hide | Hide all
D980400-B.pdf
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