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Bipolar motor and Arduino with a Darlington Array - circuit modifications


One of our visitors, Thomas, is reporting that the motor in the circuit described in the original post Driving a Bipolar Stepper Motor with Arduino and ULN2803AG continues to operate even with pull up resistors R1-R4 removed.

I'm scratching my head  :-\  Anyone knows if there could be enough current passing through the ULN on the output that's supposed to be open to sustain rotation of a small rotor?

Thomas, if you can describe it in more detail, I would appreciate that!


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