We’ve had our silkscreen made, and got a working prototype for a board game “module” with shift registers, leds and printed circuit board – but there’s something that feels a little uneasy about the whole manufacturing process – it’s very long winded, requires a lot of effort, can easily go wrong and- ultimately – very expensive.
We’re determined to come up with something that’s cheap(er) and easier to make.
So the first thing to do was simplify: lose the leds and concentrate on making a large input matrix. Suddenly we were back to an earlier idea – copper tape and cardboard!
The basic idea is to create a membrane style matrix – criss-crossing lengths of copper tape and separating them with a “mesh” between the two layers (a layer with lots of larger holes cut into it). Then by applying pressure onto one surface, the two bands of copper tape touch and create a crude pushbutton. A description of this approach can be found here (http://forum.arduino.cc/index.php/topic,13091.0.html)
Unlike a push button matrix, we don’t have a great amount of force pressing onto the contacts, only the weight of the playing piece, to activate the button. What we needed was a cheap way to pull the playing piece down onto the contacts – magnets of course! If we placed a ferric-based (steel/iron) board under our playing surface and embedded a small magnet in the bottom of each playing piece, there would be enough “pull” on the piece to drag it down, making the pushbutton contact. But A4 sheets of steel are not easy to come by, even in the BuildBrighton hackspace.
Now not everyone appreciates that the change in UK coinage in about 1992 meant one important thing – changing from a cupro-nickel to a copper-plated steel for one penny pieces means that any penny coin made after 1992 is attracted to a magnet. So we set about making a matrix of penny pieces:
On the lower board we ran some tracks of thin copper tape. Over this we placed a laser-cut separator, made from 2mm mdf (a penny coin is about 1.6mm thick). Into these holes we dropped some one penny pieces