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TexElec makes the best version of this adapter, and does ship to the UK, in case you wanted to just buy something.

Otherwise, try this page: https://mitxela.com/other/midi_spec

Hi. MIDI uses a current-loop interface, an opto-coupler is being recommended.
The resistor solution is what makes those cheaper models of USB-MIDI cables so unreliable.
The 5v for MIDI port should come from its own pins, rather than from the other computer's MIDI port - hence the opto-coupler.

NadJ wrote on 2025-02-12, 17:38:

Think I've bitten more than I can chew. […]
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Think I've bitten more than I can chew.

I have a SoundBlaster AWE64 with a DB15 style game port. The MIDI adapter cable for these are impossible to buy in the UK, so I decided to make one by buying a DB15 modular breakout connector and a standard MIDI cable. I've spliced the MIDI cable hoping to join the 5 wires (plus ground) to the DB15 connector. I did this after coming across a pin out diagram:

http://www.suntekpc.com/htm-2/cb-midi-5mm-15f … le-and-male.htm

But looking at this more carefully, looks like they might be using various resistors and possibly even capacitors! (electronics isn't my forte).

Has anyone done this before?

Thanks

Yeah do not use that schematic.
the site keenmaster486 posted has a proper schematic, though since you lack any electronics knowledge and I guess soldering skill I will also side with the buy yourself one option.
This https://www.serdashop.com/DB15MIDI has two midi out ports. it lacks midi in, though I don't know if he'll ship to the uk even though it's not that far from the uk. 😀
This https://texelec.com/product/sb-midi-joystick-adapter/ expands to midi in, out and a two joystick ports.

edit: the schematic on the mitxela site is labeled Figure 2: Joystick/MIDI Adapter Diagram

I second that, the schematic by keenmaster486 is the proper one.
It might look a bit complicated at first, but it isn't on a closer look.

TaxElec seem to market their's as SB compatible
Seems the safer bet. 60 dollars with shipping. I've done worse.

Cheers guys

The author of HardMPU-wt has a MIDI cable project that you can easily make one based on.
https://github.com/PickledDog/sb-midi