External battery with L293D

I am pretty new with electronic circuitries. I followed this excellent tutorial Adafruit Learning System and I got it working. :slight_smile: However, I have one question, on my project, I need to use a large motor, I need to use an external battery pack dedicated to the motor so that the Arduino and the motor have separated power source. What puzzles me is that in the tutorial,
the two terminals of the motor are connected to pin3 and pin6 of the L293D chip, I am not sure how to attach and external battery. As always, any guidance will be greatly appreciated. :slight_smile:

The motor power goes to pin 8 of the L293, see attached pic.

edit.... the motor power -ve goes to the Arduino / L293 ground to give the motor power a circuit.

Thank you JimboAZ, thank you very much for you guidance, it works great, I just have one more question, in the tutorial I mentioned above, it seems to omit the pin4 and pin 5 GND, I followed your diagram, connected them to GND, either way it seems to work, what is the different to have grounded? Thanks again.

Glad it works.

The diagram you linked to does actually show pin 4 to ground. The 4 grounds 4, 5, 12, 13 are all electrically the same, and also may be soldered to a heatsink.

l293 pin4.PNG

Oh yes I didn't realize pin4 and 5 are already connected internally, duh :blush: