Finally made some progress with the speaker project; I have started to wire up all the electronics and mount them in the housing.  Fortunately it looks like it is all going to fit :)  Now I just have to put the stand alone arduino in place and it will be done.


I have also found a different use for the light switch switch that I started making last year.  Due to the four buttons on the remote I thought perhaps it would be better as a quiz controller.  By lighting up each button a different colour and coding a quiz on a computer with corresponding colours, the idea would work nicely.

After trying to work out how to control the computer with picaxe, the microcontroller I originally used in the project; I came to the conclusion my best bet was to hack open a keyboard and try and use a few transistors to act as 'electronic keys'.



 The keyboard I opened had a large plastic sheet (3 layers) with copper tracks attached to the top and bottom layers and a hole in the middle layer corresponding to the location of the keys.  Each key basicly pushed the top sheet down enough to make it touch with the bottom sheet and complete the circuit.  After establishing which output pins were used for the top and bottom layer I started trying to solder to the main board (left).  At first however I couldn't, the pads had a graphite (I think) coating.  Luckily a Christmas present came in handy.  I used my new Dremel to sand off the top layer of graphite to reveal the bottom layer of copper.  This had varying degrees of success, but eventually I was able to make enough connections to produce 4 different keyboard inputs.

I hot glued 4 npn transistors to the back of the board and them soldered the collector to the common bottom layer pin and each emitter to its top layer pin.  Finally I connected some crimped ribbon cable to the 4 bases. After testing this out, I then set about adapting the original reciever board.  Luckily I had used an oversize chip so I could use the rfout command.  This left me with 4 digital IOs next to each other to which I soldered a SIL header for the ribbon cable to connect to.

The board looks a mess because after originally testing I realized that a buffer chip would be required.  Hence the mess on the back of the board.
After quickly editing the original code I was able to send the states of each push button over the RF link and then the corresponding letter would appear on screen.  Now I plan to write a piece of software for my computer in which I can use this to run a wireless quiz.




I have also started to learn the basics of Eagle CAD.  To the left here is the first component I have designed.  It happens to be a small dot matrix which I hope to use in the future...





Comment