[Article] Arduino Trick: Using a low gain opto-isolator for MIDI

Other Hardware Audio
1

Hi, there.

I just finished writing an article on how to use almost any opto-isolator for MIDI with Arduino just by adding one NPN transistor, and an explanation of why the 6N138 works and the 6N136/4N25 won't "right away" at the end.

Hope it's useful and I'm not breaking any forum rules by posting an article on my own website.

It's both in english and spanish.

http://acidotunismo.com/en/2013/10/arduino-trick-using-a-low-gain-opto-isolator-for-midi/

Best regards

2

Looks great. sure this will be really useful.

3

Hello,
thank you very much for explaining!

For the optoisolator input current assumption, why do you assume 15 mA?
Isn’t MIDI supposed to be a 5mA current loop?
Thanks in advance!