Please Note: The wiring of the
2235-DP and
2238-Con can also be used with the 2237-SP Board
Thank you for your purchase of our Model 2235 Series USB Button Interface. The Switch Assignments are involved but can be easily accomplished with the help of the following information.

If you have any comments or need additional information on the use of the
2235 or 2238, please write us at:
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Wiring and Installing the 2235 , 2237 And the 2238 USB Interface Boards
Installing the USB INTERFACE requires very little time. All you need is an unused USB Port. Additional Ports can be added to your computer by using a device called a USB Hub. These Hubs can be purchased for as little as $20.00 in the Internet.
Highlight "USB Interface Model xxx" then click "Properties"
From the photo above, you can see the J1 and J2 connectors of the 2235. The connector on the left is designated J1, while the connector on the right is J2. J1 & J2 are both 2x17 male "Headers" giving you 34 pins for each connector. Note the "RED" Square on each of the Headers, The "RED" Dot indicates that this pin is Position #1. The pin to the right of pin 1 is Position #2. So in other words, the J1 and J2 pins facing the Integrated circuit connecte directly to the chip's inputs. The pins located near the edge of the board is the Common Ground for ALL Toggle Switches.

To better understand the 2235's input, connect the board to an unused USB port on your computer. Click the appropriate icons to get into your "Calibration window". Then using a screwdriver, short out each adjacent pins on the J1 and J2 connectors. The corresonding "RED" Button will light for about 1/4 second. When the short is removed, the same "RED" Button will light for a second time for another 1/4 second.

The animation below depicts the output pulses on each input (Note: Only 20 RED Buttons shown on the Animation).

SPST Toggle Switches require only 2 wires to operate. To make wiring of your switches as easy as possible, the 2120 was designed so that 2 adjacent pins on the J1 and J2 connectors need to be shorted together to provide the 1/4 second pulse associated with this closure. The second pair of J1/J2 pins are used for the next Toggle switch. And so on. Do you see a pattern?

Wires #1 and #2 are connected to Switch #1
Wires #3 and #4 are connected to Switch #2
When you have completed the assembly, it's a very easy task to plug-in the 2-pin togle switch assemblies into the appropriate J1/J2 male connectors (see the 2235 board shown above).
If you want multiple LEDs, just wire up the additional LEDs as shown above. But this time, make the +5VDC a common connection for all switches. The additional toggle switches are to be connected to the 2120's J1 and J2 as previously discussed.

When wired, just mount the Toggle Switch onto the panel but with the orientation when the toggle is UP, the LED turns ON. That's It!

The toggle switches used with the 2235 are standard Single Pole Single Throw (Double Pole Double Throw can also be used) devices and is available at many electronic supply houses on the internet. Such as B.G. Micro  For your convience, Desktop Aviator also makes these toggle switches available at reasonable cost. You can find these switches at:


With your purchase of the 2235, we also provided Thirty-one 2-pin female connectors. All you need do is to solder two wires from the Toggle Switch terminals to the 2 pins of the female connector. Below is an example of how to do this. Seeing that the toggle switch is applying a "GROUND" to each of the 2235's control pins via J1 and J2, the length of wire you use to solder the switch to the 2-pin connector is not a factor. It can be as little as 3 inches to as much as 4 feet. If you wish to make the assembly two feet or more, it is recommended that you use a "Paired wire". Something like speaker wire. It has no effect on the operation of the 2235, it just looks better.

Make 30 more of these simple switch assemblies or less if you wish.
Wiring LEDs to the 2235

I've received a number of emails asking how to wire an LED indicator light to the 2235 using the SPST Toggle Switch. Well, here it is!

Below is a simple schematic on how to just that. All you need is a 330 ohm 1/4 or 1/2 watt carbon resistor and either a RED or GREEN LED. Seeing that the LED will be mounted above the switch it is an easy job to wire the components.

Solder a short piece of wire from the FLAT end of the LED to the Top terminal of the Toggle Switch. Now, take the 330 ohm resistor and solder it to the ROUND SIDE OF THE LED. LEDs are a polarity sensitive components and can only be installed one way. If not, you run the risk of distroying the LED.

Now, the other side of the 330 ohm resistor needs to be connected to +5VDC. This voltage can be "stolen" from the computer's USB Port via the 2235 board at the location indicated on the schematic below.

Also note that the Toggle switch terminals must also be connected to the 2235's J1 and J2 connectors. So using the 2-pin female connectors that came with your purchase, solder the two terminals of the toggle switch to the 2-pin connector.

Now place the 2-pin connector at J1 pin #1 - #2 (RED Dot). Now, with the 2235 connected to your computer's USB Port, flip the toggle switch. The LED will go ON and OFF. If the LED remains ON at all times; just remove the 2-pin connector from the 2235 board and reconnect it but this time "flip" the connector around.

Wiring Spring Return Buttons to the 2238
The 2238 operates and is wired just as the 2235, except, the 2238 uses a Spring Return Push Button in place of the Toggle Switch used by the 2235-DP.
As the 2238 creats a pulsed output, the 2235 produces a constant ON output to the USB port of your computer. This constasnt ON will remain until you remove your finger from the push button. Below is an animation on the USB output generated by the 2238 Interface.
Wiring the Model 2235

Below is a photo showing the 2235/2238 Board with its J1 and J2 Headers. It is here (J1/J2) where we will connect the Toggle Switches.
These Green Push Buttons can be purchased from our Parts page
These 2-Pin Female Connectors are included with the purchase of the 2238 Board
Wiring the Push Buttons is  very. Just take a length of Stranded wire (Any length to 24 inches), solder two wires to the terminals on the back of the Push Button Switch. Solder the other two ends to the 2-pin connector as shown to the left. When completed, just wire 30 more switches.

To complete the assembly, just take each 2-pin connector and insert it onto the J1 and J2 male Headers. Just as you would do for the toggle switches.

When complete, goto the Calibration Window; select "USB Interface Model 2238" and press each of the 31 buttons. The corresponding RED Button
will light and stay lite until you remove your finger from the switch. This output can also be seen for the remaining 30 switches.

Now using the Flight Settings from your FS2002, FS2004, FSX, FSUIPC or X-Plane, you can program each button to simulate the desired flight functions
Just plug a USB Cable Series "B" into the jack on the 2235, then into the USB Port on your computer. The computer will sense the Adapter and load the required software for its proper operation. The 2235 will be sensed as "USB Interface Model 2235-DP or USB Interface Model 2235-CON as seen to the left. To verify that your computer has accepted the Interface, you can goto the "Game Controller" window. To do this, just click on "START" (located in the lower left hand corner of the computer's monitor); then click on "Control Panel"; then  "Game Controller" Your computer should display the following: 
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Wiring  Rotary Switches to the 2238
I've shown you wiring a SPST and a SPDT Toggle Switch to the 2238 board, but what about Mechanical Rotary Switches? No Problem. As you already know, the flightdeck of a 737, 767, 747 ect also have rotary switches to select between flight functions. Below is a drawing on how we can wire the 2238 board to a 5 position Mechanical Rotary Switch (You can also use switches with less then 5 positions or one with more then 5 but less then 10 positions).
Just like the wiring of multiple Toggle Switches seen above, we can use just 1 "Common" wire (GROUND) and 5 "Control" wires. Take a Rotary Switch and turn it over to look at the side with the solder terminals. You will see something similar to the photo above.

The common terminal of the rotary switch is soldered to any of the "Common" wires on the 2238's J1 Connector (see above), while all the "Control" wires are soldered to the switch's "select" output terminals. That's all there is to it. If you have a rotary switch with more then 5 positions, just continue soldering wires to J1's remaining "Control" pins.

When purchasing a Mechanical Rotary Switch for your panel, NO NOT get one called a "MAKE BEFORE BREAK". This type of switch connects the next terminal to its common pin before breaking its connection with the previous terminal. You need to purchase a switch called a "

Wiring  LEDs to the 2235

Wiring  Switches to the 2235

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