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From: Roger Johansson
Subject: Re: Reed Switch "dead spot".
Date: Mon, 02 Sep 2002 18:25:10 +0200
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James Meyer wrote:
>>How about this? use two reed switches place in 90 degree offset and
>>electrically in parallel so any one switch on would close the circuit.
> How about this? Place the reed switch vertically at the center of the
>square and use a "normal" magnet with the poles oriented up and down in the
Wouldn't it be a lot simpler using electrostatic sensing, or
Imagine a pcb-board as big as a chess board. Etch circles divided in
the middle on every square. If a chess piece with al-foil in the
bottom is placed over such a pattern it will short the two halves of
the square capacitively, which can be sensed electronically.
The pcb-board can be painted with black and white color, so the
distance between the piece and the copper is the thickness of the
paint, which gives good capacitive coupling.
Mechanically this is a lot simpler than putting magnets in the pieces
and mounting lots of reed switches.
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