The new multiplexer circuit is finished! Now you can switch between the step/dir signal inputs from either the pc or the joystick for easy manual control of your cnc machine.
joystick controller component side artwork. (New version posted 11.06.03 to fix a bug)
joystick controller back side artwork. (New version posted 11.06.03 to fix a bug)
joystick controller parts list.
Below are some pics and info on how I designed and built the board.
I've got the logic circuit all layed out and tested, so now I just need to breadboard it and test it. Here is the logic for one axis.
Well, after a long night of messing with the design, here is what I came up with. To get 4 axes working together, it took a bit more logic than I first though, but here is what I came up with. The board is only 3.24" x 5", so it isn't too big. There are 8 IC's on the board, so hopefully in version 2 I can simplify it. Now I just need to run the design through the laser printer and make the artwork. Then I'll iron it onto the copper clad and etch it.
Here are both sides of the board printed on the clay faced paper.
Put the two PDF artwork sheets together and hold it up to the light to make sure the top and bottom vias line up.
Now tape the two PDF's together along two edges so that the traces and vias line up and nothing moves.
Now get your board ready by cleaning it with a brillo pad and then use soap and water to remove all residue of oxidation and oil. Dry with a clean paper towel. Don't touch the board again until after you iron on the image because the oil in your fingers will keep the toner from sticking.
Crank your iron up full blast and use a medium pressure to transfer the toner to the copper clad board. This board took about 5 minutes or so on each side to get the toner to transer. You might have to play with this a while to get the feel for it, but you can usually tell when all of the traces have transfered because the traces change color a bit.
Cool the board in water for a few minutes to stabilize the toner and then soak the whole board in water and a bit of dish soap for 10 minutes or so. You should then be able to peel the paper from the board. You might have to scrub it with your fingers or a wash cloth to remove all of the paper, but it will come off.
You can see where the toner didn't quite transfer in this shot. The problem traces are black because the clay and paper residue didn't stick.
You can touch up any fault areas with fingernail polish and a toothpick. It doesn't look all that great, but it works.
Now into the cool homemade etchant tank made from a 99 cent store tub and an automotive windshield washer pump. The etchant will eventually eat away the pump shaft, but I have 5 etches on this one and it is still going strong.
Carefully place the board into the Ferric Chloride and fire up the pump.
After about ten minutes, the board is ready to remove from the tank. Rinse the board in cool water to flush away the Ferric Chloride.
Drill, populate and test the board and you've got it!. The messed up traces don't look all that great, but they work.