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Entry  Sun Jan 14 16:52:53 2018, Craig, DailyProgress, TempCtrl, High Current Draw for Vaccan Temp Control Causing Nonlinear Voltage Spikes 20180114_CTNLab_TempControlSpikes_6hours.png
    Reply  Sun Jan 14 20:40:26 2018, awade, DailyProgress, TempCtrl, High Current Draw for Vaccan Temp Control Causing Nonlinear Voltage Spikes 
       Reply  Mon Jan 15 21:35:14 2018, Craig, DailyProgress, TempCtrl, High Current Draw for Vaccan Temp Control Causing Nonlinear Voltage Spikes 
          Reply  Tue Jan 16 10:57:50 2018, Craig, DailyProgress, TempCtrl, High Current Draw for Vaccan Temp Control Causing Nonlinear Voltage Spikes 20180116_OvernightVaccanReheat.png
             Reply  Tue Jan 16 19:10:29 2018, awade, Craig, DailyProgress, TempCtrl, Debugging vac can heater circuit: heat, oscillations, leaking current. 20180115_HeaterCircuit.pdf2018-01-16_19.08.57.jpg
                Reply  Wed Jan 17 23:40:15 2018, awade, Craig, DailyProgress, TempCtrl, Debugging vac can heater circuit issues: oscillations everywhere 2018-01-17_21.20.58.jpg
                   Reply  Mon Jan 22 20:30:11 2018, Craig, awade, DailyProgress, TempCtrl, Debugging vac can heater circuit issues: oscillations everywhere CTN-Lab-Heater-Circuit.pdf
                      Reply  Tue Aug 20 11:19:35 2019, anchal, DailyProgress, TempCtrl, Vac Can Heater Circuit repaired CircuitCloseup.jpgBoxOverview.jpg
                         Reply  Wed Aug 21 16:17:47 2019, anchal, DailyProgress, TempCtrl, Leave the Heater Circuit Alone! 
          Reply  Tue Feb 27 14:17:13 2018, Aaron, DailyProgress, TempCtrl, High Current Draw for Vaccan Temp Control Causing Nonlinear Voltage Spikes 
             Reply  Wed Feb 28 10:20:40 2018, awade, DailyProgress, TempCtrl, Heater and temperaure sensors in cryo lab GroundingDoGroundingDont.jpg
Message ID: 2108     Entry time: Tue Feb 27 14:17:13 2018     In reply to: 2050     Reply to this: 2109
Author: Aaron 
Type: DailyProgress 
Category: TempCtrl 
Subject: High Current Draw for Vaccan Temp Control Causing Nonlinear Voltage Spikes 

I think I'm seeing a similar problem that y'all were when I use my heater circuit (which is I believe the same as your heater circuit, it's the one Kira and Kevin are using at the 40m). Our temperature readout circuits might be slightly different.

Basically when I have the heater on the board as my readout op amps, I get up to a few tenths of a volt jump in my temperature readout; however, even after moving this circuit to a different board and using a separate power supply, I'm getting about a millivolt shift. This is not good for <1K control. I'm also well within the limits of my power supplies, have voltage regulatorsbefore the OP amps, etc... I will try swapping out the OP amp as you did, but thought it was a pretty weird problem.

Quote:

After some extensive testing, the circuit appears to be working as expected.  The only exception is the affect the temperature control circuit has on all other electronics connected to the +24V kepco power supply.  The model number on our electronics rack is ATE 36-3M, and is a Size "B" Quarter Rack model, rated for "Approx 100 watts" of power, with max DC voltage of 36V and max current of 3 amps, according to Table 1.1 of the manual.  Our current readings on the power supply show between 1 and 2.5 amps at 24 volts, with the current depending on the 0 to 1.5 amps the vaccan heater draws.  So our max power output from the power supply is 60 watts, well within the power limits.

 

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