Buttons

Adding Buttons

My friend Walt Ottenad devised this clever method of adding all the keys you need to your wheel and dash. It involves cannibalizing a keyboard and creating contact points to which you can attach switches. I should add, at this point, that there's an alternative to his method. It's called an "EPIC" card. The Extended Programmable Input/output Controller (EPIC). Guys that build their own flight simulators use them to configure switches and buttons to flight sims. They are, however, quite expensive ( several hundred bucks worth! ). Personally, I prefer Wally's method for ease of use and for economy! You be the judge.

Circuit board 1 - The circuit board that you see above is from a cheap keyboard that I purchased at a computer show for $12. You can see the pairs of contacts that the keys strike to activate letters, numbers, and commands. I've circled the F12 contacts to illustrate how they are traced to other points on the board. The points in this case are dots of solder where resistors are attached to the printed circuits on the matrix. Using a continuity meter, I traced 25 of these points that connect with all the "key" contact points on the matrix. When used in different combinations, they produce strokes of any keys on the keyboard. For example, if I hook up a switch to points 16 & 20, I can produce the F12 function key. The white lines represent continuity between the key contacts and the dots of solder. Tracing these can be a real pain in the neck, but it's worth the hastle. Just take your time and be methodical. Use a permanent marker (razor point) to mark these areas. I started with the "Esc" key putting one probe of the continuity meter on one of the contacts, and then slid the other probe on all the solder dots until I found the one that produced a beep from the meter. That means they're connected or you have continuity. Immediately, I jotted down the results i.e., Esc=8+1. Continue with this process until you've traced all the keys, or traced the ones that you'll need. I opted to trace them all so that later on I could connect wires from all 25 points to a barrier strip. From the barrier strip, I can hook up a button for any key that I need. Simply number the lugs on the barrier strip to coincide with the numbers on the solder points. Then, refer to your chart for which two lugs to connect for any given key command. The illustration above shows how this is done and as an example, I've shown how I would hook up a button to give the Esc command.

Circuit board 2 - This is another kind of keyboard with a mylar printed circuitboard. Mylar is a thin, flexible plastic sheet, it comes plugged into the matrix and can easily be removed. However, don't remove it until you've traced the contacts that you're going to use. Below is a diagram of what you'll find inside the keyboard housing. Use a continuity tester or your multi-meter to trace all the points you'll be needing, or while you're at it, trace all of them for possible future use. This kind of setup is much easier to trace than the first example, because all the solder points are in a single line just beneath the socket for the mylar circuitboard. First, number the small mounds of solder with an extra-fine permanent marker, or stick a thin strip of tape or paper next to them so that a pen or pencil may be used. Proceed as indicated in the first example and record the results. You now have a "map" of which contact points will produce any given keyboard stroke. Wiring momentary buttons from your dashboard to these points, will have you ready to control your sim from the driver's seat.

matrix

This is how my wheel looks from the back. The keyboard matrix in this picture is from another keyboard that I purchased from Computer City. It's smaller than the one that I spoke of before because, it didn't have a hard circuitboard. Instead, the circuit board was a sheet of mylar that plugged into the small matrix shown in the photo. If you can get a keyboard that's similar, then you'll find it not as difficult to trace. All the connections are in a line directly below the insert plug for the mylar circuit sheet.

When you're finished, attach the matrix to you wheel and plug it in as you would for your keyboard. Warning! Don't unplug your keyboard while the computer is turned on!

Thanks to Tony Parreiro, here's a diagram for a switch box that allows you to have both keyboards plugged in at the same time. You can flip back and forth from your wheel keyboard to the regular one by means of a SPDT switch.