Putting a MIDI synth into a MIDI plug is something we’ve seen a few times before. In fact, [mitxela] did the same thing a few months ago with an ATtiny85, and [Jan Ostman]’s DSP-G1 does the ...

Your MIDI keyboard should now be successfully interfaced with your computer, potentially via your audio interface. This hurdle cleared, you are now unfortunately through the looking glass – and may be ...

That’s it on the left, next to a standard MIDI cable plug. The whole thing is so small it fits inside a MIDI plug and can run off the power supplied by the MIDI output, driving a small pizeo buzzer.