By Bojan Zivancevic
17 April 2000
I gained basic information from two sites which contain load of information regarding this topic. The authors are Lew Wiegand and Mark Gauntlett, but it seems that Lew's site changed the address and I will try to update the link. They were both very kind to allow some pictures to be taken from their sites, so these guys deserve to be mentioned here.
My wheel is based mostly on Lew's design, but Mark conceived some things also. But, it isn't a copy of those wheels and you should use your own ideas too! This guide is here merely to put a "worm" in you head which will make you build your own wheel.
Finished controller will be very inexpensive and will have great "feel". It will not be better than those manufactured wheels (well, maybe even better than some of those cheap ones) but it will be fun making it, you will save great deal of money and you can adjust it to your liking!
I suggest that you read the whole guide before you start making anything. Don't be discouraged if you don't understand everything at first. As soon as you start working, things will start to open up.
Almost every picture has a big brother. :) This means the pictures that appear on the page are very small and you can't see a bloody thing. But when you click on them you will get a proper picture (a big brother) so you can study things up close.
I want to describe the principles of this wheel controller thing. When you finish your wheel, it will be reported to the windows just like any other joystick. That means that whatever device you make (flight yoke, wheel etc.) it will be the same to windows. So, how does the Windows see it? Controllers usually connect to a game port located on your soundcard. This port has 15 pins and to us important are 4 pins for buttons, 4 pins for controller axes and two pins for the power line and the ground. Standard PC joystick can hold four buttons and I strongly suggest that you attach all four of them to the wheel. This is an easy part. But what about the axes? The joysticks use only two axes - one for the left/right movement and one for the up/down movement. Because of that, the other two axes that are available are referred to as "axes on Joystick number 2". But if we build a wheel, we can use as many axes as we like, even all four of them - for the wheel, the clutch, the brake and the gas! If you drive a sim with a joystick, you must use the gas and the brake on the very same axis, which is a shame. It's not realistic damn it! We will describe the complete process of achieving that realistic feel with our newly built wheel. To the right you can see the picture of the PC game port and the meaning of every pin (courtesy of Mike Gauntlett). The Windows needs to have some kind of variable resistance connected to adequate pins. Thus it knows in which way the controller has been moved - as the movement changes the resistance changes also and everybody is satisfied :). Variable resistors are called potentiometers or pots. We will use one for the each axis we plan to use. I didn't use the clutch because I mainly drive F1 sims, but you can add it if you like. When you comprehend the principle, it will be a piece of cake. The pots have three pins on them lined up in a row. They have initial value and that is the resistance between the outer pins. It never changes, that's important! The only resistance that changes is the one between the outer pin (either one) and the center pin. The center pin is in fact the slider that can be moved from one side to the other. This means that when the slider is moved towards one side the resistance between those pins is dropping, while at the same time raising between the center pin and the other outer pin! So, we will use only two pins for our purpose, the center and one outer pin. We will connect the wheel and pedals to the pot shaft (which is of course connected internally to the center pin) and achieve that our controller is giving Windows just the variable resistance it needs.
On every page there will be specific data that you can use freely. I used those components and it works good. But it should serve only as a guidance, everybody should adjust these values to themselves. To conclude this introduction I want to say that building the wheel/pedal system is not a big deal, but you must think before you act, plan things ahead and have a lot of patience in your pocket if you are just entering in the amusing world of home-built things. If you are experienced, you can make the wheel within a week. Believe it or not. :)