Re: stepper motor power issues...

On Jan 26, 11:32 pm, vwkafer <LKran...@xxxxxxxxx> wrote:
I have a pair of unipolar stepper motors that I am trying to drive
with a combination of a PIC16F877 and ULN2003A.  My code and
connections seem to be fine, but I am having trouble finding a power
supply/voltage regulator combination that has enough juice

Regulated voltage is good for PIC chips, but completely
senseless for stepper motors. Best performance of a
stepper power source requires regulated current, not voltage.

Use a current limit resistor for each motor, and connect to the
power supply at the isolated unregulated point (for a linear
power supply, the terminals of the big filter capacitor).
Don't try to give the steppers lots of current, they are unlikely
to need the maximum specified torque anyhow...

And always remember that stepper motor windings are inductors,
there will be stored energy that can burn up your switches
instead of turning off... you'll need to put protection diodes into
the circuit.
.

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