midi thru 4

It has optimized schematics for 5V and 3.3V MIDI sender devices, optimized circuitry for optocoupler to minimize false triggering and improve sensitivity. Finally it uses hex inverter with a Schmitt trigger for driving a stronger output signal. This makes it very reliable device. This is an active circuit, so it does require an external power. That’s the way it should be according to the MIDI specs.

This TRS version is capable to set a MIDI specification per port for TRS-A or TRS-B by moving jumper settings. This provides the flexibility to interface it with all vendors no matter of the specification used.

There are several options for providing a power:
To be used with Eurorack 16pin power supply and sourcing 5V from eurorack
To be used with Eurorack 10pin power supply, sourcing 12V from eurorack and doing onboard 5V conversion

Board size and an enclosure choice: Eurorack size: 2HP, PCB Size: 10.8x4.3cm

https://deftaudio.com/store/tproduct/921862440862-eurorack-midi-trs-thru-1in-gt-4out-midit