A simple passive tester to identify if you TRS Midi signal is Type A or Type B.
3 x boards from Oshpark cost about $2.
When building, ensure you get your LEDs the right way round!
BOM:
1 x 3.5mm Stereo SMD Audio Jack CUI SJ-3524-SMT-TR or equivalent
1 x 330 Ohm 0603 resistor
2 x 1206 LEDs suitable for reverse mounting KPTL-3216SYCK or similar (A 1206 LED with a circular / cylindrical lens - not a square lens - will fit into the hole.)
