Hi,
I've been seeing comments about the need for a diode in motor circuits. Do I need a diode when I'm hooking up a 12 Volt windshield wiper motor to a motor controller (the motor controller is this one:www.pololu.com/catalog/product/1373)?
No, any commercial board should be protected and the manual doesn't say anything regarding such matters either, so they obviously don't expect you to put an external diode on it, but if in doubt, shoot them an email - after all, there's a lot of people that believe the L293D doesn't need external diodes.
If you have room for a diode, it won't hurt anything to use it of course, but it has to be a really fast diode to be really effective.