Help with Stepper Motor Drive

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Hi

I need to implement a stepper motor drive for a line following robot.

The circuit diagram I'm thinking of making is attached below. I want to know if there is any way to reduce the components. The power transistor takes up a lot of space and the 2W resistance in series with the diode also takes up space.

I also want to know if the opto couplers can be removed(safely). Also will i be better off using a bipolar drive with one of those ICs with two H bridges?

Aakash

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it all depends on the stepper motor. you can run 2 unipolar steppers with ULN2804 chip easily.
there is no need for the opto chip. use a small resistor instead (a few hundred ohms).

but if you are dealing with a bipolar motor, use a stepper driver chip instead. it's much simpler.

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Thanks

Are you sure removing the opto chip, and making the grounds common won't create any noise problems?

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Quote:
Are you sure removing the opto chip, and making the grounds common won't create any noise problems?

It highly depends on the PCB layout.
Divide the area in "control" and "power"
You need to connect the power_GND and the control_GND on one point but have two solid planes.
Keep the current at the GND_connection low.

Klaus
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use capacitors if you fear the "noise" so much. i made my circuit like that and nothing crashed. just avr->ULN->stepper. if you use this you don't have to use extra diodes as well as they are built in the ULN.

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Alright, thanks. :)