Opto-couple confusion – 6N137 or 6N138?


Following on from USB to MIDI connections, and Notes on optocouplers, I realised that I, myself, had become a bit confused and mixed up my optocouplers.

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?

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Minimal AVR kit


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?

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Assembly of an MK8


There are an awful lot of cheap MK8 extruders, and their derivatives (close and not so close), out there – with different number of parts, different bolts (lengths and thicknesses), screws, washers,  varying arm designs (enclosed or non-enclosed bearings), etc.. However, not many assembly instructions. So I’ll ramasser a few different assembly pictures here.

This post was inspired by How to build the extruder motor holder for the Kossel Mini

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EZ-code for ZXSpectrum


This question, How were the first ZX Spectrum games written?, got me thinking about how I used to code the ZXSpectrum, which was using assembler, via a BASIC program (not app) called EZ-code, which came from the excellent book by William Tang, Spectrum Machine Language For The Absolute Beginner. Then I found this question Where can I get the errata sheet for Spectrum Machine Language for the Absolute Beginner?

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