By inspiration from the flight sim expert Kev Saker, I decided to try a brief suggestion given by him in one of his articles, on Flight Sim.com, as it relates to hard-wiring the entire simulator to a keyboard card and it worked. By doing this, you will need NO solenoids or EPIC cards whatsoever. The cost of the entire electrical interface (not counting wiring or switches) is around $15 versus the EPIC card method which could cost hundreds of dollars. I must state though that the EPIC card is one of the most powerful expansions that can be added to a simulator, but it comes at a price.
VERY IMPORTANT if you plan to use indicator lights, please do not put them on the same switches and lines as the keyboard card or you will most likely blow the keyboard card out. Figure E1-4 (near the bottom of the page), shows a proper technique for connecting indicator lights without disturbing the keyboard card. E1-4 is a more complex component, so refer to figure 1-2 to see the simplified version. Remember that the keyboard supplies it's own power supply so you will not need to worry about any manual power supplies unless you intend to use indicator lights.
To construct the electronic interface for your simulator, you will need a keyboard, switches , and lots of wire. The type of each of these parts that you will need is as follows:
Keyboard: PS/2 and USB keyboards can be used simultaneously, but since USB keyboards only work in Windows (I think), it's best to use the USB keyboard for this interface.
Switches: Only momentary buttons should be used in conjunction with the keyboard card, or else you will get a key repeat whenever you activate a button. A circuit is in the works that will allow toggle switches to be used.
Wires: 20 - 22 Gauge works well for most applications.
Barrier Strips: These strips allow you to instantly connect a wire to an extension wire on the keyboard card using only a small screw driver. They also prevent the exposed ends of each wire from touching thereby preventing accidental signal crossovers.
Constructing the Interface
Note: This interface has been tested with AT and PS/2 keyboards, but not USB. Theoretically, everything should by all means work exactly the same, but this has not yet been proven. USB results will most likely be posted before the end of June, but in the meantime, this method definitely works with PS/2 as well as AT keyboards.
You will now need to strip the keyboard down until you are left with three transparent sheets, an electronic keyboard card, and a long connector cord. Do not remove the plastic sheets yet because they play an EXTREMELY important part in this interface. The part of the keyboard that you will need to be concerned with are the two slots that the transparent sheets are connected to. By connecting a wire from the "short" slot to the "long" slot, you can create any keyboard output that you'd like. Each keyboard has different signal requirements (slot combinations) and that is why you'll need the transparent sheets to determine which pins on each slot control each letter. You may also want to keep the keypad so that you can determine which node on the sheets corresponds to the letter you want.
The sheets work like a schematic and work as follows: If you want to create the letter "g", you would directly line up the transparent sheets and place them in an upright position. Now locate the node which corresponds to the letter "g" as in figure E1-1 (place the sheets on top of the keypad to help locate the node if needed). Now, on the top sheet, locate the node that you just marked/remembered for the letter "g" and follow the line that it is on until you reach the signal port (long slot or short slot) on the keyboard card as in figure E1-1. Now, note which pin the line ended at, and repeat this process for the bottom sheet. These two values represent the signal required to create the letter "g". The shortcut method to this is to simply cut a short wire and connect it between each port and record on a sheet of paper what letter was produced. In other words, bridge the wire between port 1s, and 1L, and record what letter is produced, then bridge the wire between ports 1s and 2L and record the letter produced... etc. You should then have a chart of every key on you keyboard and what letter it produces. Of course You will need to connect your keyboard card to your compuer to do this.
1 - A port number
So the values on the diagram below could be summarized as 4s, 10L
Now to send the signal for
this key to the computer, all you need to do is take a wire and place one end in the pin
you marked on the short slot, and place the other end in the pin you marked for the second
slot as in figure E1-2 (once you remove the transparent sheets). As you can see, Figures
E1-1 and E1-2 are exactly the same except one uses the transparent sheets, and the other
uses wire and a micro (lever) switch, although any momentary push button will work. That's
it. You have just created the letter "g". It is a hundred times easier every
time you do it and you can now repeat this process for each switch and button you plan to
use. Now, you may safely remove the transparent sheets. The middle sheet, that has nothing
on it, is useless and can be discarded at your own leisure unless you plan to reassemble
the keyboard. There are a few major points that I must make in regards to the interface
before you begin adding a lot of buttons.
Note for PS/2 Keyboards...
Because many letters will use any given node, and the nodes are very small, it will be necessary to connect extensions as shown in figure E1-3c. These are nothing but strips of wire with one end connected to a pin and the other end left free or connected to a terminal/barrier. This will allow you to add as many wires to each slot as necessary. Whenever you want to connect a switch to a particular pin on the keyboard card, you will instead connect it to the corresponding extension wire or terminal. If you use a terminal strip, you will only need to screw the wire into the proper terminal, but without terminals you will have to fire up your soldering iron everytime you want to attach wires. John Hastie from Australia provided a very helpful technique in which you remove the signal ports (the long and short slots that the transparent sheets were connected to) in order to allow the easy connection of your extension wires. To do this, flip the keyboard card over and locate the soldered pins directly beneath the long and short slots. Desolder all pins directly beneath the two slots, and remove the two connection slots. Then proceed to solder in your own extension wires as shown in figure E1-3c.
Figure E1-4 shows how the
landing gear panel would generally look using indicator lights, and using Kev Saker's gear switch setup. By connecting the up
and down micros to the proper extension wires on the keyboard card, you can easily create
a working landing gear lever. You can add indicator lights to the panel as well by
connecting the gear lever to a SPST (Single-Pole Single Throw) switch and connecting each
of the indicator lights to extension wires from that switch. Just remember to keep the
indicator lights' power supply off the same lines as the keyboard card.
Creating multiple signals with one switch
A relative of fellow flight sim builder Peter Cos has recently contributed a great schematic for creating multiple button presses with one switch. We call the schematic the Popescu circuit in honor of his father in law who created it for us. It utilizes a 4066 Quad Bilateral Switch and will allow the proper creation of items such the autopilot along with any function which requires button presses such as "SHIFT + Z." A thing or two needs to be worked out before the official release of the schematic, but at that time it will be posted here with Peter's permission and I will also be releasing a revised report to FlightSim.com
* The importance of
these functions may differ between sim builders. Such as, many pilot's never use the save
flight feature. Most of these features can still be accessed via the pull down menu
Barrier Strips can be used to make the connection of switches to the keyboard card much easier. I used 8 Position barriers for my aircraft, but any barrier will work just fine. As in the diagram below, each extension wire should be connected to a different port on a barrier strip. Any wires that need to access the port should then be screwed into the opposite side of the barrier. This allows solderless connection of every wire in your sim to the keyboard card.
A recent test has shown that USB keyboards can in fact be used simulatneously with a PS/2 keyboard. This means that the USB keyboard can be hacked and used for the keyboard interface, while the PS/2 keyboard can be used for typing (i.e. in squawkbox, or to chat). Further tests are planned to determine whether the keyboard interface would work with a USB keyboard, and also to see whether a USB hub would allow more than two keyboards to be used.
I welcome any questions, suggestions, or comments about the electronic interface at AirPanther@777Project.cjb.net. Each will be answered A.S.A.P.
For problems or questions or comments regarding this web site
contact Robert Prather.