Comment by alar44

I was tasked with designing a "dunker" years ago. It dipped a basket into a basin containing a solvent. It only has to move about 3 feet, but I found that since the endpoints were hard physical constraints, a hall sensor tripping a circuit to either reverse, or stop the motor was far more elegant than trying to code it with stepper motors and way cheaper.

The whole thing was supposed to use a fancy PLC, but when I understood the use case, I ended up making it completely using analog using relays, hall sensors, and timers. It was even able to buzz at you if it got stuck. All relay logic. Mostly because I had a big leftover box of PCBs with 8 relays apiece. The clicking sounded super cool.

I checked in a while ago to see if it was still in use. They got rid of it for a fancy PLC system that cost 1000x as much but is connected to the cloud and stuff.