I'm trying to build a chess board which can automatically record a game without any help from the players. I don't need anything as fancy as actual tags on the pieces (I'm going to figure it out just by dumb dead reckoning), but I'm not sure of the most effective sensors to use for the squares. Preferably, I'd like the price to be low, but here are some of the ideas I had.
Attach magnets to the bottom of the pieces and lay a grid of wires underneath the board (it's very thin). When the pieces move up or down off the wires I should see some kind of current induced from the magnetic flux.
Second idea, was to use magnets in combination with a bunch of reed switches. This is basically the exact same idea except it's using an actual sensor which is probably going to do a way better job. The price obviously goes up pretty rapidly though ( I need a reed sensor per square, $1.50 * 64 + 1.50*24 for the magnets).
Lastly, I could use the FSR sensors listed here: http://www.sparkfun.com/products/9375
but they're obviously a lot more pricey at 6.50 a pop. Since there are 64 squares, the price is rocketing up to a cool 416 (or somewhere in this ball park). I considered maybe using square FSR sensors to bring the cost down and having them share squares. I'm not sure if that would work well.
This is my first time ever building up a full project, and I don't really have any experience with these ideas. I was hoping you guys could act as a sounding board, maybe come up with some ideas