I’m working on a project where I want to control a motorized fader with an arduino. I have a dual H-Bridge board to control the motor, but the thing is that it is a 10V motor. I’m thinking of using a secondary power supply on the H-Bridge to power the motor with a proper voltage. So here is where my lack of electrical knowledge comes into play. My H-Bridge has the following connections: a set of +/- poles to provide the power to the motors, 4 motor control pins (2 per motor to control their direction) and 4 motor power pins (2 per motor).

If I was using the Arduino as the power source for the DC motor, I would connect the +5v rail to the + terminal ot the H-Bridge and the Gnd rail to the - terminal, which would, in turn act as the ground return for the control pins.

If I am to use an external power supply, how do I wire it properly so I don’t blowup the arduino or the h-bridge? I’m guessing that my secondary power supply will be connected to the +/- poles of the H-Bridge and the the - pole will also get connected to the Gnd rail of the arduino?

Is that correct?

  • Possibly, but it's ultimately not possible to say without the documentation of this motor shield. Mar 26, 2018 at 17:23
  • @ChrisStratton It’s not an arduino shield, it’s a generic H-Bridge board. I’ll try to find more documentation, but it’s relatively hard to find the paperwork for stuff bought on ebay ;) Mar 26, 2018 at 17:27
  • To an extent, then it's not really an Arduino question. The Arduino should have a common ground with the compatible-signal-voltage "digital" side of a motor driver it commands. What happens on the power side is a question about the details of the motor driver circuit, not an Arduino question. Without documentation you may need to do some visual/continuity reverse engineering from the data sheet of the driver IC or raw circuit topology if it is made of discrete FETs. Mar 26, 2018 at 17:44
  • The board is based on a L298N chip... ill dig further. Mar 26, 2018 at 18:35

1 Answer 1


According to the datasheet on the L298 IC the connections you described should be right. First I would recommend to connect 10v to the + and - rails and measure the voltage on the logical inputs if it is 0 or lower than 3v than that should be ok to connect an arduino. Also now you can connect an additional 5v power supply with an the -5v connected to the - rail on the board and try to connect the +5v volts to the inputs and measure the voltages on the output (or connect an motor) if everything is ok you can try to connect your Arduino.


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