Cockpit hardware issues
Each client allows you now to add 8 4-channel, 8-button joysticks. This depends on how many game controller cards you have in the PC, and how many USB ports you have available for USB game controllers/joysticks.
Everybody knows the use of a stick or yoke as a flight control, but what should you do with more?
As you may know, there are throttle controls on the market that just connect to an USB port like a joystick. If Windows can read them as just another standard joystick, FsXPand will be able to use its input. Each PC will send the stick data to FS and allow you to add more controls (see compatibility list).
A magneto, flap or spoiler control works in exactly the same way.
Besides, you can make your own hardware custom controls easily.
The controls on a stick are easily replaced with simple components, built into your own centre pedestal.
A regular control is no more than a combination of one or more linear controls (variable resistors or linear potentiometers) and one or more spring-loaded switches. This means, that you can create your own custom aircraft controls, by coupling your mechanics with such potentiometers and switch buttons.
This is not very difficult. Once you have learned to handle a soldering iron, and have the guts to disassemble some old joystick, you will soon see what I mean.
Joystick ports are found on game cards or sound cards, or on a USB convertor. The stick is connected to a 15-pin connector.
USB sticks are nothing more than the internals described below, with a convertor to get the data serialised into the USB port. Convertors are available on the market to get any stick to work with USB ports. The additional advantage: no jitter, they are stable.
The inside of a 2-channel stick shows two variable resistors and two pushbutton contacts. The voltage supplied by the PC is reduced by the variable resistors, dependent on the stick position. The remaining voltage read by the port is translated into a digital value the PC can evaluate. If you push a button, the 'hot' wire of the button becomes grounded, that is zero Volt. The PC reads the digital value directly. Every millisecond or so, the PC operating system polls the stick for input.
More advanced sticks have a throttle control and sometimes a rudder control. 4 buttons with coolie hat is a usual configuration.
Should you wish to use 8 separate buttons, you will need to do a bit more work. The coolie hat stick has a little device translating all 8 button pushes into 4 channels of information. The coolie hat buttons can be connected to external buttons and you would be set. This could even be done for the use of 15 buttons on 4 channels.
The schema shows you how a regular controlis wired internally. The 15-pin D-connector is shown, seen from the side where the wires are soldered. You should leave pins 12 and 15 alone - they could be in use for midi in and out.
Each control element is easily replaced by one from the local electronics shop. Take so called 'potentiometers' with a value of 100k (kilo-ohm). Put a round knob on a rotary potentiometer, to obtain a frequency set control, a lever on a slider potentiometer to get a flaps or spoiler control, etc. A reduction gear will allow you to use an actual trim wheel.
You could even take a rotary switch and solder some resistors on it to simulate a magneto switch.
Or buy some simple push buttons, or switches that hold their position. Very useful for gear up and down, we do not want to hold a button down during the entire flight.
The use of buttons can be handy, to spare analog controls. For instance, you could use a push button to increase or decrease some frequency value by 1, 10 or 100, or use it to switch something on, and off again with the next push.
FsXPand allows you to use both kinds of functions: buttons or switches.
Take extreme caution messing around with PC connectors. If you have to do some wiring, disconnect the plug from the PC. Soldering irons tend to bear high voltages, not dangerous for life but enough to send a few milliamperes through your precious chips. Dependent on what burns down, the chain of events is impredictable and you could end up with a silently deceased computer afterwards. Another recommendation is never to plug or unplug with a PC running, but since the old 8088 days I never had any problems with that. See for yourself.
Another warning for those who like to use double switches that make a light bulb switch on on the panel simultaneously. Plugging in passive components is quite harmless; if they bear a voltage of their own, be warned. One small error and you send the lamp supply voltage into the PC...
Thanks to Dai Griffiths for the wiring diagram.