I looking for advice on the best way to implement a power supply for my project. There are three elements to the project:

  1. a piezo mixer / preamp requiring a bipolar +9 / -9V supply (schematic attached);
  2. a SparkFun Red Board requiring 7-15V;
  3. a Big Easy Driver requiring 8-35V driving this stepper motor.

I had planned on using a Music From Outer Space Wall Wart Power Supply (configured as +9V / -9V) until I realized that the Big Easy Driver requires more amps than the MFOS Wall Wart supply provides: "You can use any kind of power supply (desktop, wall adapter, battery power, etc.), but verify that whatever choice you go with is capable of providing up to 2A and falls in the range of 8V to 35V."

My questions are:

  1. Would the attached block diagram work in regards to using the positive and ground of a bipolar power supply to power the RedBoard and Big Easy Driver?
  2. What would you recommend to power my project? I am having trouble finding a circuit that provides +9V / -9V and 2A. I would like to be able to have a single plug and on / off switch.

Thank you for your help!

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  • 2
    \$\begingroup\$ That stepper motor wants 2A per phase, so the peak draw is likely to be well above that. I would recommend a separate supply for that alone -- then you also won't be restricted to the same voltage that the rest of the system is using. \$\endgroup\$ – Dave Tweed Jul 15 at 2:02
  • \$\begingroup\$ Thank you, Dave! What is the best way to implement a second power supply but still only have a single plug to the wall? Or, if I am able to find, say, a +9V / -9V power supply capable of delivering 3 or 4 amps, am I correct in my method of connecting the positive and ground in parallel with the RedBoard and Big Easy Driver, which only require a unipolar supply? Finally, why is it difficult to find bipolar power supply kits that deliver 3 or 3 amps? It seems like they mostly top out at 1 or 1.5A. I would like to build my own if I can find a PCB kit with clear instructions. Thanks again! \$\endgroup\$ – xYx'oO Jul 17 at 19:57

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