2020-06-13 (Sa) HexShaftMonitor COMPLETED

The problem I was having was the large magnet on the rotating shaft would trigger the reed switch twice during a single rotation. If this was a matter of dividing by two, I could double my sampling rate, and the problem would be solved. Unfortunately, the reed switch was triggered twice in short succession, and then there was a long lull as the magnet went the rest of the way around. Plus, not everyone will have this problem, so it made more sense to figure a way to make everything work. First, I tried stacking a small magnet on top of the existing disc to focus the flux lines into a smaller area, but that didn't do the trick. Next, I placed a steel washer over it to try dampening the field, but that didn't help either. Lastly, I held the sensor with one corner near the magnet, and it behaved as I wanted, so I taped it to the base where it would only trigger once per rotation.

When I ran the drill, I couldn't measure below 200RPM because the timer would expire and erase the speed before each rotation. 200RPM is pretty slow, roughly three turns per second, but when I'm winding coils, it will be more important to know a slow speed than have a quick timeout. I changed the code so it can measure as slow as 30RPM, but it takes two seconds to erase the rate once the rotation stops. While I was changing things, I also changed the long-press necessary to reset the rotations with a short-press.
Part of the code as viewed in Python

I uploaded my Blockly code to GitHub and put a link at the bottom of this page. Lastly, I recorded a short video demonstration of the HexShaftMonitor. I got it on the second try because I messed up some wording the first time, but the hardware performed every time since I last uploaded.
(0:38) Demonstration of HexShaftMonitor

GitHub repo for HexShaftMonitor.

The rest of the posts for this project have been arranged by date. First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Completed projects from year 7

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