Aviation communications training aid

Thread Starter

Doccarson

Joined Sep 2, 2017
35
I was hoping to get some design assistance in putting together a training aid for my student pilots. I'd just like to make a system where two people with headsets could plug in and use a PTT switch to activate it like you would while flying. Possibly making it modular to add more inputs for multiple people. The idea is to have one person take the air and ground controller role and the others to act as pilots. Any input would be appreciated.
 

MisterBill2

Joined Jan 23, 2018
10,602
The arrangement to provide PTT communication will depend a lot on just what sort of headsets are involved. With a carbon microphone and electromagnetic earphones the arrangement can be very simple, possibly requiring only a single battery. If the microphone element is a dynamic mic, or worse yet, an electret element, it becomes a lot more complex.
So let us know which type of microphone element is involved.,
 

Thread Starter

Doccarson

Joined Sep 2, 2017
35
Well you called it, they're electrect elements. At least that's what the Clark headsets use. I don't know if the Active noise reduction function would come into play as well, I remember a co-worker of mine mentioning that to me a few years ago, but the context escapes me at the moment. I got this from the Clark website if this helps.
 

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LowQCab

Joined Nov 6, 2012
1,635
If You want to build your own, here are some Circuits to get ideas from ..........
Both can easily be converted into a multi-channel-system.

The more complex version will provide the most "realistic" "Sound-Tone/Distortion/Compression".

If You need the particular changes,
You will need to provide the Specifications for the Headphones,
and a wiring diagram of the PTT Switches, and the Microphones,
as well as the available Power-Supply Voltage(s), ( unless You want to make it Battery-Powered ).
.
.HeadPhone Amp Flat .png
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.Simple Electret Amp Flat .png
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.
 

MisterBill2

Joined Jan 23, 2018
10,602
The beauty of a carbon mic and 600 ohm earphones is that you can use a series connection, battery, PTT switch, mic, and earphone and that is all that it takes. And depending on how much volume is needed, one AA cell can last a long time. REally, about as simple as possible.
 

JohnInTX

Joined Jun 26, 2012
4,629
That’s a great idea. You might look into an inexpensive intercom setup or an intercom circuit you can build. If you’re doing this on the ground you might be able to use cheap gaming headsets.
 

Thread Starter

Doccarson

Joined Sep 2, 2017
35
Well I'd like to have it so the people are using their headsets they already have. I reckon it doesn't need the push to talk aspect, that was just for immersion purposes. Though the more I think, it's probably just easier to talk it out instead of trying to make something overly complicated.
 

MisterBill2

Joined Jan 23, 2018
10,602
REally, learning the limitations of Push To Talk is important. Folks used to cell phones have a hard time waiting for the other person to release so that they can talk. PTT is totally different from what most folks are used to doing, so that will be a vital part of the learning.
 

MisterBill2

Joined Jan 23, 2018
10,602
I recently learned that some aviation headsets, even with electret microphones, have circuitry to emulate a carbon microphone. Those headsets might be able to function in the very simple series arrangement, although certainly polarity requirements would need to be followed. That would be the simplest arrangement of all. You will need to get the application information as far as voltages and polarities from the manufacturer so that we can provide the required connections advice.
 

Yaakov

Joined Jan 27, 2019
4,074
I am assuming these are standard G.A. headsets with 1/4” (PJ-055) and .206” (PJ-068) connectors. Since these are very standard the creation of a multiuser intercom with PTT would be “easy”, but there are a lot of details and it is a complicated project. If you want to pursue it, I think the best way would be to find modular amplifier boards that can handle the signals from the mike and to the phones, and work out a way to put them on a bus which was selected with PTT.

Once more idea that strikes me as a possibility is to use inexpensive, low powered two-way radios (like FRS) and actually do the exercise on the air. I am uncertain if the Family Radio Service would allow this, but I am sure that you could find a service where it would be permitted. In that case, the goal would be to buy or build an adapter from the G.A. connectors to the radios input and output. It would actually be a very realistic way to do it, including allowing people to step on each other. It would be FM, though, and not AM, so the interference would sound different.

Something like this might be used to allow people to use their headsets and phones, running a voice chat application, to simulate operational comms, but it wouldn’t include PTT.
 

MisterBill2

Joined Jan 23, 2018
10,602
If the headsets truly emulate the carbon microphone of years gone by, that output will be at least a volt, with a typical 4 1/2 volt supply, although 5 volt supplies will be more available. That will very adequately drive those magnetic earphones. But with multiple users it would get more complicated..
And the most challenging part of the older PTT radio sets was waiting for the dynamotor to spin up so the radio would transmit correctly. Probably few folks recall that type of equipment. Repeater users sometimes do need to keep the same proactice, not all repeaters change over instantly.
 
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