[simpits-tech] Small CRTs (Was: Just a quick update.........)

[Gene Buckle]

On Thu, 12 Apr 2012, dabigboy at cox.net wrote:

>
> ---- Gene Buckle <geneb at deltasoft.com> wrote:
>>
>> Just be aware that a pc keyboard does not use a diode isolated switch
>> matrix, so you'll only be able to hold 3 or 4 "keys" down at once before
>> the keyboard stops responding to inputs.
>
> Yep, I'd noticed that. That's why I've only ever considered it for the 
> FMS or another keypad'ish task, where I will probably never be pressing 
> more than one button at a time.
>
You can add diodes yourself like so:
http://www.geneb.org/ematrix.png

This is for the EPIC input matrix, but it would be essentially the same 
schematic for hacking a keyboard matrix.  Once you identify the row & 
column lines it's easy.

Alternately, you could just grab an Arduino and a Centipede Shield and 
skip the whole keyboard mess to begin with. :)

g.


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