This is a really simple AT90S2313 (I know, obsolete) Midi-CV converter, giving a 1 Volt/Octave signal. There is a trigger out and also glide out, which is allways on, while two or more keys on the midi-keyboard are pressed. This can of course be much more sophisticated, you will find everything on this page to build your own version.
The Midi Channel is fixed and can only be changed per software. This feature can be modified, of course.
Here is an oscilloscope picture of the CV out in the upper trace, the lower trace is trigger out...
...showing that the device principally is working.
The schematic is straight forward. Lowpass filtering of the cv-out signal is not so usual, this is just to ensure filtering of high frequency noise coming from the digital part. This not a must. Be sure to not use resistors after the cv-out, as these of course will change the v/Oct-characteristics.
And the PDF-file of the PCB and Component setting. Also, there is a link to the Coreldraw 9 - File, containing all you need to change the lyout to your own need.
PDF :
and CDRAnd of course the source code for the E-LAB Pascal Compiler. This should work with the evaluation version. If not, tell me, then I have to add a HEX file !