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Entry  Thu Aug 4 15:15:32 2016, Aidan, Summary, TempCtrl, RTDs used in aLIGO TCS RHs 
    Reply  Thu Aug 4 18:01:03 2016, rana, Summary, TempCtrl, RTDs used in aLIGO TCS RHs 
       Reply  Fri Aug 5 00:08:16 2016, awade, Summary, TempCtrl, RTDs used in aLIGO TCS RHs 
       Reply  Tue Aug 30 10:56:51 2016, Aidan, Summary, TempCtrl, RTDs used in aLIGO TCS RHs 
          Reply  Mon Oct 10 21:01:52 2016, awade, Summary, TempCtrl, RTDs used in aLIGO TCS RHs 
Message ID: 1742     Entry time: Mon Oct 10 21:01:52 2016     In reply to: 1711
Author: awade 
Type: Summary 
Category: TempCtrl 
Subject: RTDs used in aLIGO TCS RHs 

Some tests and characteristic noise of the RH drivers: https://dcc.ligo.org/LIGO-E1000785-v1

The documentation  shows noise measurements of ring heater drivers over 0-1.6 kHz span, it would be nice to have have more resolution at LF.  

Key points about the TCS Ring Heater Driver:

  • Conversion 0.08A/V (as is, although this can be adjusted)
  • ~0.07 µA/√Hz @ 100 Hz for 100 mA 
  • ~0.16 µA/√Hz @ 100 Hz for 600 mA

What it does show is increasing noise as the current is increased across the load. It is low compared to expected driving currents for the tank (0.6 A, for 50Ω total load) but maybe note for the shields (~24 mA for refcav shields, for 50Ω heater load).

It doesn't seem to include a characterization of the thermal sensing circuit's noise.

 

Quote:

Here's the RH driver PCB for aLIGO:

https://dcc.ligo.org/DocDB/0021/D1002529/006/Driver_RingHeater.pdf

It uses this power amp: https://www.digchip.com/datasheets/download_datasheet.php?id=508953&part-number=LM12CLK

 

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