If you would like to know a little more about the Atari Punk Console before you start check out this video from Collin Cunningham, http://www.youtube.com/watch?v=Oi3dmSMpjsU
This article from Jameco also has some useful info. http://www.jameco.com/Jameco/PressRoom/punk.html
Step 1: Get a Joystick
Finding and Selecting a Joystick:
Finding a joystick has been fairly easy in my experience. Literally every time I have gone to Goodwill or Salvation Army there have been at least five. They are usually around three dollars. Keep in mind the simpler the joystick the easier it is to convert. Some more complicated joysticks, such as the one on the right in the first picture, actually use an optical system and not potentiometers to track their position. This might be great for a project with Arduino integration but for the purposes of this project its far too complicated. The square shape of the one in the middle made it very easy to mount everything, but it did have a few unnecessary buttons. For this Instructable I will be using the one on the left. It only had one button that did not get used and although the curved shape made it a little hard to mount everything it looks much more sleek.
Testing the Joystick:
Once you have a joystick selected you will want to open it up and marvel at its simplicity. Once you have finished doing that, you will want to hook up a multimeter up to each of the two potentiometer that the control column (the stick part) is attached to. There will be a third potentiometer not attached to the stick that will be taken out after, as it is not needed. You will want to hook up one lead of the multimeter to the center leg of the potentiometer and one to either of the side ones (polarity doesn't mater here nor does which of the side legs). So far every joystick I have dissected has used a 130K ohm potentiometer for both axises but it is worth testing just to make sure. Once you have determined the value you are going to want to remember it because you will use it to determine the value of a second set of potentiometers you will add.
Determining Which Wires are Which:
Part of this build involves using the original trigger or "fire" switch as a sort of kill switch for the punk console. Since there are two switches on the joystick and we only need one we will want to determine which two of the three wires going into the stick itself we will need to utilize the trigger (my stick only had 3 wires although if your stick has more buttons it will probably have more wires.)
As long as you have your multimeter out you may as well set it up to do a continuity test and do this now. Hook one lead of the continuity tester up to the black wire and the other lead up to any of the remaining wires and pressing the button you wish to use, if the multimeter beeps, or lights up, or does whatever yours does, you have found the combination of wires you will use for the switch. If it doesn't, keep hooking it up to different wires till it does.