🚀 go-pugleaf

FOR SALE:  MIDI KEYBOARD CONTROLLER KIT - GREAT SCHOOL PROJECT

When I was a bald-faced college boy in the mid-1980s, I tried to build a 
strap-on synthesizer.  For many reasons (not the least of which being that 
MIDI came out during this time), my pursuit underwent several different phases 
until I separated the controller part from the synth part, got close to the 
finish line and basically gave up, "overcome by events," as they say.  Now 
that I am an old man, I have decided that while the synth part still has some 
promise, I am never going to touch the controller part.  I need some 
enthusiastic soul to pick up these guts from my sagging arms.  They could form 
the basis of the coolest senior project of anyone in their class.  Better 
still, if you finish the controller as a strap-on, you can make like George 
Duke when you're done.  Here is what you get:

One three-octave full-size AGO-37 keyboard.  This keyboard arranges the keys 
in a 5x8 switch matrix.  I am supplying a custom-made PC board that accepts 
the ribbon connectors from the keyboard and brings all 13 lines out to the 
left rear of the keyboard.

One rectangular custom-made plywood case.  The case has no top or rear cover.  
The side panels of the case are cut so that the top slopes downward at an 
angle of about 20 degrees and the AGO-37 keyboard mounts so that it slopes at 
the same angle.  You can easily fabricate your own top and rear covers with 
any controls you may desire.  The case is designed to wrap around the 
keyboard's left, forming a natural place to put wheels or other expression 
controls.    The left side panel has a large circular hole into which a 
section of lathe-turned PVC pipe has been attached.  The far end of the pipe 
has been cut at an angle to facilitate the attachment of a box intended to 
contain pitch and mod wheels at a comfortable angle if the case is used as a 
strap-on.  The pipe is secured inside the case with two removable screws.

Two Moog-style thumbwheels with pots and angle brackets.  One has a center 
click-stop and both are unsprung.  I believe these wheels are exactly like 
those on the Moog Prodigy, Rogue, and Source and differ only in color from 
those on the Memorymoog.  I am also supplying a metal box with milled slots 
for the wheels.  Use or don't.

One PAIA MIDI keyboard controller kit, circa 1988.  I already assembled the 
circuit board, which lacks only a CPU to be functional.  I am supplying the 
preprogrammed EPROM.  The circuit accepts control-voltage inputs from two 
wheels and sends Pitch Bend and Controller 1 (mod) data accordingly.  The kit 
sends only on channel 1, but there is a straightforward way to change that.  
If you look in the assembly software listing, you can see that there is a 
place in the code where the MIDI Note-On command is transmitted and you can 
see that in the course of building that command it must include a 00h - i.e., 
channel 1.  What you want to do is to be able to insert the value 
corresponding to the MIDI channel of your choice, i.e., 00h to 0Fh.  Oh, you 
can redo the code and reblow the EPROM if you want to, but I would suggest 
doing something less intrusive.  Slap some gates or a PAL on the EPROM's 
address lines such that when the address gets to the point where the 00h is 
hard-coded, you disable the EPROM such that it "lets go" of the data lines.  
Use that same signal to enable a buffer attached to the data lines that will 
assert 00h-0Fh when enabled.  What's behind that buffer making the 00h-0Ff is 
up to your imagination; you can have 16 "radio" buttons, a keypad, a debounced 
rotary encoder with click-stops, up/down buttons, whatever - but you may want 
to take steps to insure that the value is prevented from changing while the 
buffer is asserting the data bus instead of the EPROM.  Note that the channel 
numbers' four MSBs are always zero, so you could conceivably use that to your 
advantage with respect to parts count.   I supply all docs.  You need to 
furnish a power supply.

EXTRA CREDIT:  You can probably use the same technique to make the mod wheel 
send something other than a Controller Code 1.

A real challenge would be to implement an octave shift.  I don't know if it 
would be easier to rewrite the code or not to add or subtract 12 from the note 
number.  If you left the code alone, you'd need a way to intercept the note 
number and supply another one in its place, either the same one, the same one 
+12, or the same one -12.  You could use QMCF logic reduction to come up with 
truth tables for the addition and subtraction and set up a ten-in/eight-out 
gate arrangement (ten-in = eight of note number plus two for octave select).  
HEY!!  WHAT AM I DOING?  *YOU* FIGURE IT OUT!!!

I will gleefully box everything up and send it to you, AS-IS, NO REFUNDS, in 
exchange for a money order of US$50.  Email jhubbs@csra.net if you are 
interested.