Awhile back, I postulated about using rc servos as drivers to simulate mechanical gauges or meters.
Yesterday, the final piece of this particular puzzle arrived from China, some 0-5 volt servo controller boards.
I have my bench Rugid Computers RUG9 controller programmed to read an LM34 temperature sensor and output it as a scaled 4-20 ma 30-90 degree signal. There is a 220 ohm load resistor to create the voltage, across which I have the 0-5 volt servo board connected, and a micro servo connected to that.
After I made sure it all functioned, I found a random meter face on the net, printed it and glued it to a piece of cardboard and cut it out. The servo is mounted behind it. The hand or needle is a black zip tie.
Here is a video of the first test run. It's not calibrated, and the one "undocumented feature" is that the servo works backwards (higher temperature/control voltage = counterclockwise rotation). I can fix that in programming. I stuck my home made probe alternately in hot water and ice water.
BTW, the servo below the dial face is controlled similarly by a Davis anemometer. Unfortunately, the wind was calm when I did the video.
https://youtu.be/qM1SzYCl5J8