user4843: I'm successfully running a stepper from my Arduino via a ULN2003A and a secondary power supply. It uses the first four of the seven Darlington Pairs on the chip, leaving three spare.
A) Is there any reason I wouldn't be able to use one of the remaining pairs to drive a standard DC hobby motor? (For the sake of helping future visitors .. what about running three motors off the remaining three pairs?)
B) Do I need anything other than to connect the motor to the chip? (The chip's board has LEDs and resistors on each of pins 1 - 4, but I don't believe they're in series and thus my guess is they can be left off.)
C) The DC motor is on a PWM Pin. Is that the correct way to control its speed?
The image attached shows the setup in case I haven't been clear.

(I could probably just build it and see, but I'm new to Arduino and still scared of the blue smoke if I get something wrong!)

user2881: Should work just fine. But you'd have to connect the motor to the positive rail, and since the ULN2003 can only sink current.
Normally when connecting a motor, you'd add a flyback diode. But the ULN2003 already has those inside the chip.
PWM is the easiest way to (somewhat) control the speed of a DC motor.

4843: <p>I'm successfully running a stepper from my Arduino via a ULN2003A and a secondary power supply. It uses the first four of the seven Darlington Pairs on the chip, leaving three spare.</p>

<p>A) Is there any reason I wouldn't be able to use one of the remaining pairs to drive a standard DC hobby motor? (For the sake of helping future visitors .. what about running three motors off the remaining three pairs?)</p>

<p>B) Do I need anything other than to connect the motor to the chip? (The chip's board has LEDs and resistors on each of pins 1 - 4, but I don't believe they're in series and thus my guess is they can be left off.)</p>

<p>C) The DC motor is on a PWM Pin. Is that the correct way to control its speed?</p>

<p>The image attached shows the setup in case I haven't been clear.</p>

<p><img src="https://i.stack.imgur.com/JdOsN.png" alt="enter image description here"></p>

<p><em>(I could probably just build it and see, but I'm new to Arduino and still scared of the blue smoke if I get something wrong!)</em></p>
 2881: <p>Should work just fine. But you'd have to connect the motor to the positive rail, and since the ULN2003 can only sink current.</p>

<p>Normally when connecting a motor, you'd add a flyback diode. But the ULN2003 already has those inside the chip.</p>

<p>PWM is the easiest way to (somewhat) control the speed of a DC motor.</p>
