I want to control ~50 stepper motors using a single driver, and use only one Arduino pin to control each motor.
Currently I'm using a single A4988 driver and a couple of 12v 1amp stepper motors to prototype a part of a machine as a proof of concept, but I need to use many larger motors and better drivers in near future.
As I don't need motors to work simultaneously, I want to use a single driver to control them all.
I tried to validate my idea using 4 different relays and it seems that motors work perfectly as my needs (I tested and switched between them in a 24 hours long test). But as transistors are much cheaper and smaller in size, I want to use them if possible.
I have programming background and never designed a circuit before, but bellow is a schematics that I designed to control two stepper motors with a single driver, I don't know what kind of transistors or resistors should I use, or is this schematics possible at all? (As I mentioned, I already used a "4 relay module" instead of transistors and it worked well).
here is the schematics:
Any help to fix the schematics problems and choosing transistors and resistors would be appreciated.
p.s. As everyone in the comment section is suggesting to use multiple drivers I want to clear it again: Using multiple drivers is not an option, because I need to control larger motors and I need more expensive driver, which I can't afford many of them in a prototype. Any suggestion to use a single driver to control many motors, preferably using a single pin per motor is considerable. Thanks.