The circuit below is a MIDI standard-compliant 5 x MIDI Thru Circuit. Each MIDI Thru port generates an exact replica of the MIDI signal on the MIDI In port.

MIDI connector pin numbering can be found here.

Parts List:

• C1 – C3: 0.1uF Ceramic Chip Capacitor
• C4: 47uF Electrolytic Capacitor
• D1: 1N4148 Small Signal Diode
• IC1: 7805 Voltage Regulator
• IC2: 6N136 Opto-Isolator
• IC3: 7414 or 7404 Hex Inverter
• R1, R3-R12: 220Ω Resistor, 1/8-watt or 1/4-watt
• R2: 10kΩ Resistor, 1/8-watt or 1/4-watt