[sdiy] Electronic organs revisted: using organ manuals and pedals for synth DIY projects, etc

[Dave Kendall]

On Sep 18, 2011, at 02:16, aankrom wrote:

> So I'm looking at the shcematics for the Kimball 600 organ
*snip*
>  With the 74C923 I should be able to have a 20-note keyboard. Or maybe 
> I could just not use on of the pins and use it like a 74C922.

The fairchild datasheet for the MM74C922 shows a way to expand two 
922's up to 32 key operation, just by adding a 4-input NAND gate, 4 
diodes and 4 resistors. Could probably be easily adapted for your 923s, 
possibly by ignoring the 923's pins 5 and 15. (It's on page 10.)

cheers,
Dave