Using Voltage regulators with the l293d

Hey, I just ordered some l293d motor drivers and I was reading http://luckylarry.co.uk/arduino-projects/control-a-dc-motor-with-arduino-and-l293d-chip/this tutorial on how to use them. When mentioning voltage regulators, I got a little confused on whether or not they are necessary. I will be using an external power source (4 AAs) to power the motor which is about 5 V. Will I need voltage regulators? And if so, what type and uF capacitor should I use?

Not for the motor supply - the batteries can directly power the L293.

Keep the arduino power separate if you can.

What do you mean by separate?

power the arduino from one source and the shield from one source, they only need to share ground, not power. this keeps noise from the motors isolated from the arduino's sensitive signals.

Then why does the person from the tutorial use a capacitor even though he is powering it from external batteries?

because capacitors also help block motor noise and ensure that the chips have a cleaner power supply when there are high current pulsed loads. grumpy mike has a good explanation of it

http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Ok, thank you. That makes a bit more sense.