“This is a quick and dirty way to get a whole bunch (up to 17) small stepper motors working off a single arduino, with no extra circuitry whatsoever.
Why would you want to do that? Maybe you want to make a wall display, a clock or some other interactive object, and you can’t afford thousands of dollars for motors, and hundreds of hours spent wiring up boards for ‘proper’ drivers.
(Side note, the back story to this is for a while now I’ve been wanting to make a big-ish display simulating vector fields, and I was scratching my head trying to come up with a way to do it that wasn’t ridiculously expensive. I ended up finding one that was not only cheap, but lazy too!)”