Making you own PC-Midi interface for an MPU401 card.

Schematic
Join me for a walk trough the schematic.

At the top we see...
-J1.	Incoming signal
-R2.	Current limiting resistor
-D1.	Reverse voltage protection (static discharge)
-ISO1.	Optocoupler 6N138 !
-R1.	Pull up resistor

Down below you find...
-J2.	OUT plug
-R3,R4	Current limit resistors
-P1.	Connector to the PC's soundcard

All VCCs should be connected together, all GNDs should be connected together.

PCB
This circuit can  most certainly be  build on a piece of pre-printed (and pre
drilled) PCB. The profs amongst us can design a PCB is they like.

Housing
This circuit will fit into a standard sub-d housing. The two DIN plugs can be
attached  to the  circuit  by two  pieces of  cable. If you're setup is fixed
(and/or you have easy  acces to your cabling), you can even consider mounting
2 MALE DIN  plugs  onto  longer  cables  and  plug  these  strait  into  your
keyboard/synthesizer.  This will  save you  two MIDI cables (and some work if
you've read the other page about making your own cables.)

For compliments, suggestions, remarks or even criticism feel free to email me
at the following adress.

nctnico@cistron.nl

REMARK
I've seen a file floating  around  called  cheapmid.txt. In this schematic
pin 15 is used for 2 purposes. I can't figure out if this circuit is OK or
not. Email me if you know more.