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Topic: 6 Wire Stepper and ULN2803A (Read 10263 times) previous topic - next topic


@ Mike

Yes I was very new to all of this when I fried the Driver, I didnt know there was a dial on the driver to adjust the current. I was always wondering why the stepper moter squealled at a high pitch.
Funny thing is, I asked about it on the Pololu forum and nobody even mentioned the current dial.


Hi guys! i'm trying to solve a challenge i've propose myself related with a stepper motor, ULN2803A and Arduino;

I have the same circuit as shown here before, my stepper is 12V 0,16A per winding, and I have everything working well. I'm using half-step mode to drive the motor and the current through the coils is 170mA when motor is moving and 130mA or 230mA when is stopped (current for holding torque) for full-step and half-step respectively.

The new feature I would like to add, is a control for this current of holding torque. I would like to have the 10% of this current when the stepper is stopped because in my application, holding torque is not big and with this current the motor gets quite hot. The first solution I have thought about was to place a digital pot in serie with the middle terminal of the coils (B and E) ; as the digital pot can be controlled with arduino, I can increase the resistance when the stepper motor is stopped, and in this way current can be reduced. The problem is that I haven't find out this device; the biggest current that a digital pot can flow is around 20mA .

So..what solution do you recomend me?? Thanks a lot!
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