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I am using a ULN2003 to control a unipolar stepper motor from my PIC18F45K20. When I only connect one 12 V power cable (Red), the stepper motor works in full step, however, when I connect the other 12 V cable the motor stops and emits a high pitch noise and the outputs on all the PIC ports go low.

So, in conclusion, when I connect this one specific red cable, nothing works. I tried another stepper motor (same model), and the same happened. Any suggestions on what it could be?

My motor is similar to this one I found on the web:

enter image description here

ocrdu
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Matthias
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1 Answers1

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Read this: http://digital.ni.com/public.nsf/allkb/B1CC4C64ABBC7D3C86257BC70017B9E2

Your motor may be 4, 6, 8 wire and use of the wires may depend on the way you are configuring your driver (single ended or H-bridge for example). If you are using a ULN2003, it's highly likely you are using this type of connection with one common center connector connected to your supply for the coils:

enter image description here

You need to buzz out the wiring for your stepper motor and understand what wires connect to what coils.

Jack Creasey
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