Notes:
1. Used optocoupler is Sharp PC-900.
2. "A" invertors may be realized by suitable IC or by transistor. Used resistors are with tolerance 5%.
3. MIDI cable should be length of max. 15 m. DIN connector (male) should be connected to each end of cable.
4. Cable should be "twisted pair" with common shielding, which is connected to pin 2 in both DIN connectors.