During a standard onlinevlucht, with an operating cockpit in full action, it is in the cockpit in a very ‘noisy’.

The communication between Capt and F/O (or visitor) is very difficult and often unintelligible. Especially when the Capt and F/O a headset to wear for ATC (IVAO or Vatsim).

In order to resolve this problem, it is very interesting to an intercom in the cockpit as we can also find in the real aircraft.



  • A real aircraft intercom system to use;
  • An intercom building with specific side-of-the-box intercom-PCBS.

A real aircraft intercom system to use

Different cockpitbouwers use a second hand system from a real aircraft. On Ebay, there are several modules to purchase, which can be converted as intercom for a homecockpit.





At this intercommodules hear usually are real aviation headsets and aviation headset is not cheap. With a little luck you can a bargain be found on the Internet...










An intercom building with specific intercom control boards (pcbs)

A other solution of his specific " intercom control boards’ that are built for homecockpits such as that of Ruscool out of New Zealand.

I happen to be a few second-hand " Ruscool Intercom boards’ on the head can tap that I'm going to build in the ‘avionics pedestal’. According to the seller unused and right out of the box ...

Per user (Capt, F/O) so you have a " intercom board that are connected to each other. They include the ‘terminals’ for connection of the headsets, pc microphone, etc.
You can still expand with a third intercomkaart, for example, an instructor or observer.

Note. The previous and own intercomproject I stopped due to serious issues with the microphones, etc.



  • Electret (standard PC headsets) or Dymamic Microphone;
  • Stereo headphone amplifiers;
  • Terminals for Push-to-talk button, or link for open microphone;
  • Terminals for Enable/Disable audio to PC with switch or link;
  • Terminals for stereo input from PC;
  • Terminals for audio out to other intercoms;
  • Terminals for audio in from other intercoms;
  • Terminals for microphone input;
  • Terminals for headphones;
  • Preset adjustments for microphone gain, sidetone volume, sounds from PC;
  • Off board main volume control for mounting on flight simulator panel;
  • Power required +12Volts DC.











This intercomkaarten can be in different modes :

  • ‘Push to Talk’ switch or ‘Open Microphone (Pilot/Co-pilot to hear each other);
  • Use of a switch ‘Enable’ or ‘Disable’ when the sound to the Flight Simulator pc;
  • Compatible to make use of an I/C – R/T switch on the ACP-module, i.e. the selection of the I/C position indicates an open-mic situation, in the middle position, one can make use of the PPT(I/C), and PTT (R/T) buttons on the yokes and selecting the R/T position (spring return) is the PTT for the R/T function.

*** Intercom modes ***

On-board, one can control the volume of four cubes with a cross) of the microphone, the "side-tone" (to your hear) and the volume of the sound that comes from the pc (individual left and right channel).
And then there's a potentiometer connected to the master volume i.e. the volume of the other pilot that you hear and their own ‘sidetone’. The potentiometer can then be build in a cockpitpaneel.
On request you can also use the on-board arrangements be replaced by potentiometers.

Note. The Ruscool-intercomkaarten can't connect to the ACP panel (I/C – R/T switch) from CPFlight as the ACP-module is a closed system where no connections can be made to the I/C – R/T switch (according to Paolo CPFlight). This is very sad ...



I don't need the connectors as Ruscool prescribes in its manual, photos, or images. Manual and pictures are hereby attached.

*** Intercom_Connections___2_Stations ***

*** Intercom_Connections_ 3_Stations ***

For most of the connections I have coaxial cable (protected cable) used as required for signal transmission (microfoonverbindingen). The thickness of the coaxial cable can vary. The cable I have used is 5 mm thick and actually a little too thick. A thinner wire is recommended.

I have no coax used for the power supply and the connection of the headset speakers.


Headset MIC
The center wire of the coax goes to the Mic terminal and the protection (shield) of the coax goes to the GND.

I then at the end of the cable (30 cm) to a solderable 3.5 mm stereo jack (female). Herein comes the plug of headset Mic (or extension cable).
These are just 2 wires to solder. The medium and large slot with sluitingshaakjes is for the GND.
Then you have the choice of small or large tab.


Headset SPK
I have no coax used but three thin wires. Left channel is the left terminal, the right channel for the right terminal and the middle one for the GND.

I then at the end of the cable (30 cm) to a solderable 3.5 mm stereo jack (female). Herein comes the plug of headset SPK (or extension cable).

The large tab on the plug is for the channel to the right and the small tab for channel links.
The medium and large slot with sluitingshaakjes is for the GND.


Sound TO the PC (Mic) Connector X4
Here are 2 coaxdraden connected with the common GND in the middle. At the other end a male 3.5 mm jack. This is in turn connected with a kabelsplitter.

On the second plug of the kabelsplitter is the same connection of the second intercomkaart.


Sound FROM the PC (Spk) Connector X5
The same scenario as the previous connection. This is in turn connected with other kabelsplitter.

On the second plug of the kabelsplitter is the same connection of the second intercomkaart.

PTT for Pilot/FO
On the right-hand side of the intercomkaart there are 3 connectors with 2 terminals.
The first connector can be a push-to-talk switch to connect. When you impression, you can speak with your co-pilot/instr/observer.
Do you want to always be heard (open mic) is sufficient both terminals together with a wire.

ON/OFF sound to the FS-PC
On the second connector you can also switch places. When you get that impression, the sound goes to the Flight Simulator PC.
Do you want to always open, it is sufficient both terminals together with a wire.

Equipment failures
Two terminals are provided for each signal (GND and Signal). But to prevent ‘hum loops’ are going to get is the habit in audio systems the GND (the metal isolatiedraad of the coax) only to connect to the kabelzijde where the signal departs (Intercomkaart 1).

The other end of this coaxial cable is only with the signal wire connected to Intercomkaart 2.

On the second intercomkaart is the same scenario applied in the direction of Intercomkaart 1.

The metal afschermingsdraad must certainly be so on one side are connected. This protects the signal from external noises and signals.

Connect both sides of the afschermingsdraad than one gets ‘hum’failures. This is due to the use of a common power supply for the two Intercomkaarten.

In practice :
On Intercomkaart 1, the third connector with 2 terminals connected with the signal wire and the GND (afschermdraad). The other end of the coax is connected with only the signal wire on the fourth connector X2 (3 terminals) to the right terminal of Intercomkaart 2.

The whole scenario happens again the other way round with the other Intercomkaart but then ends with the signal cable to the left terminal (X2) of the card 1.

The images and the manual of Ruscool give clear information about this.

Master Volume
On the map, there is a coaxial cable connected with a linear potentiometer for the master volume.
This is the volume of your ‘side-tone (your own voice) and the voice of your intercomcollega(s).

You can this cable + potentiometer replaced by a longer cable. This should be a maximum of 1 meter long. You can this longer, but then you have the risk that it may be ‘noise’ can pick-up (interference). It also depends in what environment the cards with the master volumekabel are (e.g. a lot of electronics in the vicinity). The grounding of the potmeterbody can sometimes help.

Ideal is also the use of a logarithmic potentiometer i.p. v. a linear. The adjustment is made in a smaller and more accurate steps. These potentiometers are most commonly used when adjusting audio. Each potentiometer of 10k to 100k is suitable.


POWER supply
The power supply must have an output of 12V and a minimum of 250mA.

It is VERY IMPORTANT the right diet to choose, since this ensures that all faults get on your intercom system with a lot of ‘hum’ and ‘hush’. And we don't want to hear...

I have performed a test with 3 types of power supply :

  • A small ‘plug pack’ that you see in a wall outlet (300 mA) > This was the ‘hum’interference is the highest;
  • An old PC power supply > that was the ‘hum’interference a lot better. Some PC power supplies give a lot of interference, others were not. There you have a little bit of luck;
  • An old transformer with a regulated 12V output (which I had, from the period of the CB-radio) > This power supply was for me the winner. The ‘hum’interference was completely gone ...



The Ruscool Intercom boards are suitable for most common types of headsets, i.e. computer headsets, and various aviation headsets. But by changing some resistors on the PCB, it is possible to make use of ‘low-output dynamic microphones’.
This can be always on request.

The Intercom boards are also suitable for headphones with different impedances. This may vary from 4 Ohms to 75 Ohms. Some modern headsets are 600 Ohm types. The cards must then be equipped with other resistors in order to work with these headsets. This may also on request.

*** Intercom Resistors ***



First I did a test only with the intercomkaarten to verify the intercom will work (so without pc sounds).

I have first the headsets connected to both cards with the female plugs for the MIC and headset SPK.

Furthermore, it is still the power supply plug in and turn on.

It is the first experiment to the on-board volumes to adjust. Since I that, in the future, little or not going to use I suggest they finally (almost maximium). Later, the intercomkaarten inside the radiopedestal built. If that happened, one can afterwards still difficult intercomkaarten to reach on-board controls to run.

With the right 12V power supply (with grounding !) the sound is good and trouble-free.

Then there was a second test in which the intercomkaarten are connected with the pc (sounds coming from and to the pc).

Via 2 kabelsplitters are connected to the PC inputs of the SPK and MIC.

I have the pc taken with only the ATC messages (R/T IVAO). The intention is then only the blabla to hear atc using Ivap/Teamspeak.

I have at these test may find that there is a slight ‘hum’interference was heard. Also, the voices that are heard sound a little hollow, nasal.

The problem with the ‘hum’ was close to the power of the test pc (laptop). This power supply was not equipped with grounding. After pulling out the power plug from the outlet (only on battery) was the ‘hum’interference completely disappeared.

The hollow voicegeluiden with nasal I can still improve by experimenting with the software of the sound card (equalizer). Bv. Less bass and more higher tones ... (voicegeluiden).


Opm. Since I Ruscool Intercom Boards can't use the CPFlight ACP panels, I go the master volumes of the intercomkaarten connect to a separate radio-intercompanel (I/C and R/T). This intercompanel will be found between the other radiopanels in the ‘avionics pedestal’.



I had an aluminum plate cut and bent with the same dimensions in width than a ‘rack’ (slide) of the ‘avionics pedestal’.

The surface of the upright plate (bracket) is slightly larger than the surface area of a intercomkaart.

Then I on each side of the aluminum plate a intercombordje mounted. The pcbs are connected to each other with spacers and 4 bolts with nut.

I also have the aluminum plate with the necessary holes drilled for cable routing from one pcb to the other.

The aluminum plate with the intercomkaarten is then against the bottom of the ‘rack’ of the pedestal mounted using 2 bolts.

On the top of the ‘rack’ is a metal plate for the mouse. The bolts for fastening thereof should, therefore, also for attaching the aluminum plate with the intercomkaarten.

The different connections of the intercomkaarten are then connected to the different power extension cables for pc and headsets. These extension cables run to the front under the cockpit and in the pedestal.



The purchase of ‘intercom boards’ of Ruscool are not cheap.

The manual and the extra photos give a clear explanation of how all the connections must be carried out.

The Ruscool Intercom boards are small and they can be easy to incorporate or hide.

The possibilities of these cards are extensive and they fit perfectly in the world of the homecockpitbouwers.

Provided that the use of the right nutrition and following the correct connectors is the sound quality is good and trouble-free.

Additional connections for potentiometers, for example, volume of the side tone, mic, and sounds coming from the pc would be desirable.
That extra connections (+potentiometer) are available on request (custom-made).

The service from Ruscool is excellent. Any additional questions can be immediately extended answer.


I have experienced the use of the Ruscool Intercom boards’ that the sound of the pc a little dull happens and there is too much bass is heard.

Since the pc with Teamspeak does not have a sound card with a software mixer or equalizer, I have a mixer purchased in order to solve this problem.

This cheap mini-mixer (€45) I have purchased from Bax.nl. The mixer is particularly small and can thus easily be placed anywhere.

The ‘Behringer XENYX 302USB PA and studio mixerhas the following specifications :

  • PA and studio mixer
  • very compact analog mixer with USB audio interface
  • to minimize self-noise
  • power supply by USB
  • built-in stereo USB audio interface for direct connection to your computer
  • free audio recording, editing and podcasting software included
  • 150 instrument/effect plug-ins and drivers also included in the package
  • high-quality XENYX microphone preamplifier
  • neo-classic “British” 2-band graphic EQ
  • 2-track input assignable to headphone or main mix output
  • main mix bus and separate headphone output
  • including USB connection cable
  • including USB power adapter

I have, on the one hand, the mixer connected to the input "Input Line" on the mixer and the ‘Line Out’ (Spk) of the pc and on the other hand, with the input to headset speakers on the mixer with the audio cable that is normally reserved for the ‘Line Out’ of the pc, coming from the Ruscool intercom boards.

The bass I have fully closed and the treble at maximum.
The sound of the voice is now clearer and clearer and therefore better understood.

Translated by Yandex.Translate and Global Translator