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Entry  Thu Mar 4 13:37:14 2021, aaron, DailyProgress, Electronics, PSOMA S mA->MHz, ITC 502 current noise mA_to_MHz.pdf002F0263-0615-4566-9192-F57A14C8B543.jpegITC502_ASD.pdf
    Reply  Sun Mar 7 19:32:32 2021, rana, DailyProgress, Electronics, PSOMA S mA->MHz, ITC 502 current noise 
    Reply  Wed Mar 10 16:03:19 2021, aaron, DailyProgress, Electronics, current noise 
       Reply  Thu Mar 11 13:56:47 2021, aaron, DailyProgress, Electronics, current noise wire_shelf_5.jpg
Message ID: 2682     Entry time: Thu Mar 11 13:56:47 2021     In reply to: 2681
Author: aaron 
Type: DailyProgress 
Category: Electronics 
Subject: current noise 

enter Thu Mar 11 13:56:46 2021

  • On Busby low noise box AC coupled input (logged by to 1 MOhm moku channel 2)
    • measure voltage noise of a 20.5 Ohm resistor for 28 minutes
    • measure voltage noise across the same resistor in driven by ITC502 at 119.38 mA, same duration
    • python [path/to/moku]mokuDataLogger.py -c ch2 -i -d 1680 -s 64e3 --useInternal --fileType bin --MOhmr2
    • started to make a box for sensing current noise... but perhaps this is not necessary. To measure 10 kHz/rtHz frequency noise on our 147 MHz/mA diode (-> uV/rtHz), even the metal film resistors (1% tol) with the steepest temperature coefficients on digikey (~100 ppm/K) could allow 10 mK/rtHz temperature fluctuations of the resistor. Still, the room is drafty, so I also measured the noise across the resistor driven by two AAA batteries (2.4 V total, for about the same current as before).
    • What is the voltage across the diode during operation, and can I check this at some of the butterfly pins? Does the current supply remain consistent operating at the same current but a different voltage? And, shouldn't a 'low noise current supply' be quieter than a battery (at least at the frequencies where it matters) anyway?
  • While waiting for the data, assembled the wire shelf on the West wall of PSOMA, between the vacuum cabinet and He cryostat.
    • Electronics on the 2nd shelf have rails for earthquake protection. We have sufficient rails for all 4 shelves, but I left them for another day.
    • Zip-tied the upper shelves to the piping on the wall. Seems sturdy.
    • Feet have plastic sliders to dampen the load on the floor. We also have label holders in need of labeling.
    • Photos are in the ligo.wbridge google drive and some attached.

exit Thu Mar 11 23:11:33 2021


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