I finally finished my Aurora Forecaster project (wine for scale only).
The Arduino calls a script on my server which scrapes the University of Alaska Geophysical Institute website which kindly puts the forecast on in plain English, making my life much easier. The forecast is given as a Kp index from 0 to 9, for the first 6 the analogue meter moves accordingly then from 6 to there’s a sequence of LEDs. I could have done the whole thing with the meter but it will hardly ever go above 6 and I like to see the needle moving.
The meter itself is an old display voltmeter, something odd had happened to it where it went FSD at 0.1V so I did a bit of trial and error and soldered a resistor into it, seems to work pretty well now, maybe not accurate as a voltmeter but good enough for this. It draws 2.5mA FSD so shouldn’t be too bad on batteries.
I designed the scale on M$ Publisher because I lost patience with Photoshop, printed it out and stuck it in in front of where it normally says 5V, behind the glass. All in all I have to say I’m pretty pleased with how it turned out, especially as it’s the first time I’ve made anything like this.