A gauge that shows how much of the gridmix is carbon neutral based on data from co2signal.com.
I'm aware that wind power is not the only carbon neutral power source, but it looks neat with a windmill there, and it kind of rings true at least in Denmark where I'm from.
Get your own from co2signal.com for free! Check electricitymap.org for your grid ID (country code), or the co2signal.com docs for how to do a lookup using lat/lon instead of grid ID.
ESP8266 running Arduino on a Wemos D1 mini board.
Gauges are from ebay. I have replaced the 100K resistor inside with a 1K resistor to change the max voltage to ~3V, thus enabling direct PWM control of the gauge. The needle was kind of pale when I got the thing, so I painted it red while I had it open.
The box design is based on bdahlem's amazing parametric flexbox postscript file. It is lasercut from 3mm MDF and holds itself together quite neatly.
