| Building the midi switch is quite easy. Most
components are fairly standard (apart from the microcontroller
which needs to be programmed with the midi switch software).
Make sure that you use the opto coupler types specified in the
schematic, otherwise the switch might not work. The switch needs
a stable 5V power supply; if you have more than one switch,
you can use them with one supply.
Niki from Bulgaria has done new schematic drawings and PCBs
for the Midi Switch. Note that these files have not yet been
tested. Niki has also done some great fx/preamp gadgets himself.
Please take a look at his web
Important note: There are some reported
bugs in Niki's schematic (pins form optocoupler have been
swapped; please compare against the original);
please use the old schematic as the default template, because
I don't know if there will be an update to Niki's schematics
in the near future.
Switch schematic (PDF, bugs reported)
Switch PCB (PDF, bugs reported)
Switch PCB, ready to print (PDF)
You can still find the old version of the schematic (PDF)
If you do not have a PIC programmer or someone who can do
the programming for you, you need to build a programmer (of
course you can buy a programmer, but that's not the DIY idea).
In fact, programming the PIC controller is the most complicated
thing about this project , but maybe you will be doing more
PIC projects anyway. I use the TAIT programmer, there are
lots of resources on the web, even for good programming software,
and it's all for free ;-)