The Sim-Modules  




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Transponder / ADF


This Module is a combined Transponder- and ADF-Control Unit, which is very useful for both General Aviation and Airliner-Cockpits.

Transponder (XPNDR)

The left part of the Module is used to set the transponder code ("squawk") as well as the operating mode (Standby or Mode C). Additional buttons are provided to set the SPI-bit in the transmission ("Squawk Ident") or to quickly set a predefined default code, for example when leaving radar controlled airspace.

Automatic Direction Finder (ADF)

The ADF is the on-board equipment for radio navigation using NDBs (Non-Directional Beacons). Similar to the COM/NAV modules, the standby frequency can be tuned and switched with the active frequency using the toggle button. An additional button is available to enable the audio identifier, to check if the correct ground station is received.

MCP (Mode Control Panel)


The MCP-Module represents a Boeing 737 Style Mode Control Panel, which is sometimes referred to as "the Autopilot". It consists of two side-by-side Avionic-PCBs.




Every module in the system has its own ATMega microcontroller from the ATMELs AVR Series, which is a tiny but powerful controller. It operates at 16Mhz, processes all the digital in- and outputs and handles the communication to other modules and the SIM-MODULES Control Panel.



This module connects to the PC via USB/RS232 and offers everything needed to connect some real hardware (e.g. buttons, switches, rotary encoders, LEDs...) to your computer.

Addidtionally, it provides a power supply and data interface to connect other MAIN- or AVIONIC-Modules.



This module consists of 2 PCBs which are mounted back-to-back, one front- and one controller PCB. The electronic layout is designed in a way which allows the assembly of different modules with different functionality - the placing of the front components, like 7-segment displays, buttons or LEDs can be done flexibly as desired. By setting a DIP-switch on the back, the module will know which data is needed and the appropriate functionality will be automatically provided.

So, using the same PCBs, the following modules can be assembled:


Advanced Airliner Autopilot (Boeing-Style MCP)

This module actually consist of two different AVIONIC-modules side-by-side, and is mainly influenced by the MCP (Mode Control Panel) found in the flight deck of the Boeing 737 family. It can be used to control all the complex features that are offered by the auto-flight systems found in modern airliners.


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Basic Airliner Autopilot (Airbus-Style FCU)

Similar to the Advanced Airliner Autopilot, but using only one AVIONIC-module with 4 display blocks. The layout of the components is roughly based on the FCU (Flight Control Unit) found in the Airbus 320 family.


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General Aviation Autopilot

This module features a GA-Style autopilot, which can be found in the radio stack of smaller single- or dual engine aircraft. It offers various basic control modes for both lateral and vertical automated flight.




This module is used for voice communication as well as radio based navigation. It consists of displays for both active and standby frequencies, two rotary encoders and four dual-color illuminated pushbuttons. 


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This module consists of two parts - a Mode C Transponder with featuring flight level indication and an ADF Module, which allows frequency selection of the ADF/NDB receiver.

 to be continued...  

Other Modules

Of course, using different PCB designs or other wiring techniques, any other module can also be realized on request - for example highly realistic replicas of real aircraft avionics. The only limitation is the maximum number of components that can be used per module:

  • 64 digital inputs (e.g. pushbuttons or switches)
  • 64 LED outputs
  • 8 rotary encoders
  • 24 seven-segment LED displays

If you have questions regarding a specific project, please feel free to contact us at any time!

More Articles...

  1. MAIN-Module
  2. COM/NAV Radio


SIM-MODULES Printed Circuit Boards PCB
Professionally manufactured PCBs

SIM-MODULES Flight Simulator Interface
Detailed view of the MAIN-Module

SIM-MODULES Radio Stack Prototype
Prototype of a GA Radio Stack 

Readily Assembled AVIONIC-Modules

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