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

  • Thread starter creetski
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  • #1
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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.
 

Answers and Replies

  • #2
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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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