That's a great walk through. I have no idea why I was making it so complicated. I mean I hate math, but c'mon. It's just simple division? Why do they go and make it all complicated looking? I hope there isn't a ton of math in this. I know it's hard to be smart without knowing math but I can write code, and I thought that was what I would be doing. Why do I always get sidetracked like this? Just to be safe, I'll dig out a calculator.
Don't run away from things you have trouble with!
Another thing you might want to get are some 'logic level MOSFETs'
Search this site for discussions about them.
Basically they can be used with the voltage level (5volts) found on the outputs of a 5 volt UNO.
Watch these, don't get hung up on the math.
What the heck, watch them all:
https://m.youtube.com/results?q=addohms&sm=3
Spend two or three days watching tutorials, but, buy some pizza and beer first.
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