From mate.stubb@gmail.com Wed Jan 27 20:20:32 2010
Subject:Re: adding MIDI to Hammond manuals

Each port on most (but not all) of JD's encoder boards is of the form of a
64 connection matrix - 8 rows and 8 columns on a 16 pin connector. By
bridging a single row and a single column with a diode, the scanner sees
that as a closed switch.

To hook up a 61 note keyboard, you need to use 61 of the 64 connections
possible on a single port. So you distribute one side of each key contact to
each separate column, repeating every 8th key. Then the other side of the
key contacts are tied together in groups of 8 to each row. That gives you
your matrix of connections.

In the hammond keyboard, the key contacts all touch to a bus wire (one of 9)
running the length of the keyboard. To create the matrix out of those, you
would need to wire a diode to each key contact and run those to the columns,
then create the other side of the matrix by cutting up the bus into 8 key
widths, and connecting that to the rows.

OR

Buy adapter boards from JD. He has an adapter board already set up for bus
style wiring (keymux64) that should save you the trouble of mounting diodes
and cutting up bus bars.

Read this and understand it:
http://largonet.net/midiboutique/products/whatis/whatis.htm

That is the basic thing about wiring a keyboard to understand.

Drawbars is another matter!

Dave Bradley

On Wed, Jan 27, 2010 at 8:04 PM, Josh Lawrence wrote: