I'm in the planning stages of a project where I'll need at least 2 stepper motors. As an added challenge to myself, I'd like to try using just one H-bridge to drive both steppers independently from each other. My idea is to use transistors (or a transistor package) to control which motor is getting the output from the H-bridge and I'm wondering if, practically, this is a smart approach, or even possible. I'm also planning on making the H-bridge out of discrete components instead of buying a dedicated IC for it.

The project is nothing fancy, just something to help me explore and mess with stuff. It's a two-axis drawer (basically a printer) with a pen mounted in the sliders connected to the steppers and a solenoid to pick up the pen from the paper, controlled by an Arduino.

  • \$\begingroup\$ I doubt you can make this approach more cost effective, or more compact on the PCB. There will be basically no benefit. \$\endgroup\$ – dim Oct 28 '16 at 18:30
  • \$\begingroup\$ I'm not looking for cost or space benefit, I'm looking for an added challenge. I have a few stepper motor driver ICs, I'm just the type of person that likes to learn about how stuff works by exploring deeper. I have plenty of discrete components, so I won't be spending any money on parts, I just want to know if it's possible. \$\endgroup\$ – HaLo2FrEeEk Oct 28 '16 at 19:22
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    \$\begingroup\$ All right. I was just answering the "I'm wondering if, practically, this is a smart approach" part. But I have nothing against challenges with limited usefulness, and practices this exercise regularily myself... \$\endgroup\$ – dim Oct 28 '16 at 19:29
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    \$\begingroup\$ So this will just waste components, complexify the control part for nothing, and, by the way, prevent you from having two motors running at the same time at different rates. So really, there are more rewarding challenges, I think. \$\endgroup\$ – dim Oct 28 '16 at 20:21
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    \$\begingroup\$ Having separate H-bridge drives would be a more practical solution. Keep in mind that a stepper needs to be energized to have the holding torque (it will go limp when there is no current running through the windings). \$\endgroup\$ – Nick Alexeev Oct 28 '16 at 21:52

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