3 ms·

Wow, 0.001K is impressive for something you've built yourself. Care to share what approach you used?

• twawaaay 4y ago
  It wasn't anything special. I am an amateur EE and not especially talented. I did some cursory search on the Internet, found a circuit that was looking promising and brute forced it by using best components I could find and then ovenized it for great stability and removed any sources of noise I could imagine (for example using linear power supply, etc.) I think just the measurement circuit with the oven was about $500 which is just saying I did poor at optimising for the cost. But for this project the price was not an issue and the real challenge and bulk of work was in building a model and control algorithm. There is couple of gotchas. For example if you use very low current through the RTD (PT100 in my case) you get a lot of noise so you need to use relatively high current. But this causes it to heat up. Rather than try to eliminate this effect I decided to make sure this heating up is as constant as possible. This is one of the reasons it had poor absolute precision but was good for measuring changes over time.