Diodes in keyboard circuits, etc.

[Hairy Harry]

Hi All

A simple answer is that the diodes isolate the keys from each other so that 
pressing more than one key at a time does not produce an
ambiguous output.  If you look at a schematic of a keyboard matrix
(say 8 rows by 8 columns...) you will see that pressing more than one
key at a time will cause short circuits in rows / columns.

If that doesn't get it I'll try to draw an example later of exactly how this 
happens, and how the diodes are an easy way to prevent this.

H^) harry


>From: "Synthusiast" <synthusiast1 at yahoo.com>
>Reply-To: "Synthusiast" <synthusiast1 at yahoo.com>
>To: "Synth DIY List" <synth-diy at node12b53.a2000.nl>
>Subject: Diodes in keyboard circuits, etc.
>Date: Mon, 2 Oct 2000 21:30:03 +0200
>
>I wonder where these diodes that you find in keyboard circuits and matrix
>switch circuits are used for. Is it for debouncing or is it something
>totally different?
>
>Tia,
>Synthusiast
>
>
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