This one was inspired by Driving a flyback with pure AC sine wave but I wasn’t sure if my answer was a good fit to te question, so I reproduced it here.
This article was inspired by my question on Retrocomputing, on Stack Exchange, Largest memory peripheral for Sinclair ZX81? and turned into a list of links to vintage computing magazines.
Trash80 recommends using a 6N138 in the ArduinoBoy, see the schematic. I had subsequently order a batch of 6N138, in order to build an ArduinoBoy, see Making your own ArduinoBoy. Then I started looking at the use of optocouples for other MIDI applications. However, many other users recommend 6N137 for MIDI applications, and I ended up getting the two confused.
So, how different are they? Are they interchangable? Is the 6N138 the right optocopuler for the ArduinoBoy?
Many moons ago, before I knew anything about Arduino, I bought a “minimum ATmega kit” from eBay, pretty much like this, DIY ATMEGA8 Minimum System Board ATmega48 ATMEGA88 Minimum System Board AVR Kit. It arrived, I built it, I put in in a box and forgot all about it until today, when I came across it.
But once you’ve made it how can you use it and what are the buttons for?
Following on from A tiny one, my development board finally arrived, along with an ATtiny85, and this is how to use it… and it’s not as easy as it would seem.
These instructions, and troubleshooting tips should work for ATtiny 85/45/25
The book: Sound Synthesis – Analog and Digital Techniques, Terence Thomas