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

[aankrom]

I remember seeing that in the datasheet. The expansion circuit that 
uses 74LS367's can be however big you want it to be, but I imagine there 
would be some propagation delay for music applications on a larger scale 
that may be unacceptable.

AA

On Sun, 18 Sep 2011 03:10:09 +0100, Dave Kendall wrote:
> 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
>
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