Nano MIDI Proto PCB Build Guide

By Kevin on October 29, 2024

Here are the build notes for my Nano MIDI Proto PCB.

Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!

If you are new to Arduino, see the Getting Started pages.

Bill of Materials

Nano MIDI Proto PCB (GitHub link below)
6N138 opto-isolator
1x 1N4148 or 1N914 signal diode
4x 220Ω resistors
1x 4K7 resistor
2x 100nF ceramic capacitors
1x 100uF electrolytic capacitor
2x 15-way jumper header sockets
1x 2.1mm barrel jack socket (see photos for footprint)
Optional: power switch (2.54mm pitch connectors)
Optional: DPDT slider switch (2.54mm pitch connectors in 2x3 arrangement)
Optional: 8-pin DIP socket
Jumpers and header pins
2x PCB mount 5-pin 180 degree DIN sockets (see photos for footprint)
OR 2x 3.5mm stereo TRS jack sockets (see photos for footprint)

Build Steps

Taking a typical "low to high" soldering approach, this is the suggested order of assembly:

All resistors and diode.
DIP socket (if used) or opto-isolator.
TRS sockets (if used).
Disc capacitors.
3-way jumper headers or alternative.
Arduino 15-way headers.
Barrel jack.
Electrolytic capacitor.
DIN sockets (if used).

Here are some build photos.

I used a DPDT slider switch with 2.54mm pitch leads in place of the MIDI disable jumpers.

If TRS sockets are being used rather than DIN sockets, then they should be placed next.

When soldering the Arduino headers it is useful to have an Arduino Nano to plug them into to ensure they are properly aligned.

If using MIDI DIN sockets, then they are the last things to be fixed.

Testing

I recommend performing the general tests described here: PCBs.

It is worth testing with both USB power and 7-12V barrel jack (but not at the same time of course) and ensuring 5V and GND are correctly broken out to the prototyping area in each case.

The Simple MIDI Monitor can be used to check the MIDI IN and OUT is working successfully. It will indicate MIDI IN activity whilst also performing software THRU functionality back to the OUT port.

PCB Errata

There are the following issues with this PCB:

None known at present.

Enhancements:

It might be possible to mirror the layout of a mini solderless breadboard on the prototyping area to make transferring designs from breadboard to protoboard easier.

Find it on GitHub here.