How to stabilize voltage on a mV scale using a DC power source?

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SUMMARY

The discussion focuses on stabilizing a voltage of 39.000 mV for calibrating an Omega DP470 thermometer/datalogger using a DC power source. Users suggest two main approaches: purchasing a precision voltage source, which can be costly (~$1000), or constructing a custom solution. A recommended method involves using a voltage reference PMIC from Texas Instruments to output a stable 5V, followed by an instrumentation amplifier to scale it down to the desired 39mV, ensuring accuracy and noise immunity.

PREREQUISITES
  • Understanding of thermocouples, specifically type T thermocouples.
  • Familiarity with DC power sources and their voltage output capabilities.
  • Knowledge of voltage reference PMICs and their applications.
  • Basic principles of instrumentation amplifiers and their function in signal scaling.
NEXT STEPS
  • Research Texas Instruments voltage reference PMICs suitable for low voltage applications.
  • Learn about instrumentation amplifiers and how to select the right one for scaling voltages.
  • Explore methods for reducing noise in DC voltage outputs, including filtering techniques.
  • Investigate the construction of custom voltage sources using resistors and zener diodes.
USEFUL FOR

Electronics engineers, hobbyists working on temperature measurement systems, and anyone involved in precision voltage applications for calibration purposes.

creetski
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Hello,

I'm in the process of calibrating a thermometer/datalogger (Omega DP470) that uses a thermocouple type T (-200-350 deg. C range), and I need a DC voltage source that can feed a steady voltage of 39.000 mV. I believe at this point I can either purchase a precision voltage source that can feed a steady voltage on a millivolt (mV) scale, or manipulate/construct my own using my (0-20V) DC source.
The problem is that precision voltage sources are fairly pricey for such a task (~$1000.00), and I would rather construct something that can stabilize my voltage. I am able to dial down the knob on my current DC source to around 39.000 mV; however, it is obviously going to be noisy. Several people suggested putting some resistors in series and see if that would do it, while others have mentioned using zener diodes to maintain a steady voltage. I'm a little on the inexperienced side when it comes to EE and am curious if anyone out there has dealt with a similar situation? Any help or (detailed) tips are highly appreciated!

Thank you.
 
Engineering news on Phys.org
Get yourself a voltage reference PMIC (Power management IC). Let's say that you pick on that outputs 5V like this one from Texas Instruments. Follow that with an instrumentation amplifier which scales the 5V down to 39mV. Then you'll have an accurate 39mV with good immunity to noise, temperature, and offsets.
 

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