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post #1 of 12 Old 06-18-2013, 08:53 PM - Thread Starter
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Honestly have no clue where to put this topic, but hopefully you can can help me out. Moving on...

I'm a student helicopter pilot trying to save a buck. There are some aviation headsets out there that can do some pretty cool stuff. For example, Bose makes the A20 headset with Active Noise Reduction, has an AUX input and Bluetooth connectivity.

I currently have a cheapo headset that I have made some modifications to that leave me wanting more. I wired in an AUX port so I can plug in music of some kind, but in testing, the stuff that I NEED to hear (radio calls etc) get over powered by the music and become extremely difficult to hear. Additionally, I have found an ANR kit that costs a fraction of the price ($170) of the big name headsets that has nothing but good reviews.

Anyways, getting to the point of this thread. I want to buy this: http://www.ebay.com/itm/Wireless-Bluetooth-Receiver-3-5mm-Stereo-Audio-Music-for-iPod-iPhone-MP3-MP4-PC-/400465351275?pt=US_USB_Bluetooth_Adapters_Dongles&hash=item5d3d98526b

Then I want to wire it into my headset. The only problem I'm having is that I want to be able to make the music mute whenever something comes over the radio. Unfortunately I have no idea how to make this happen. Also, If possible I need to block my music from getting sent down the wrong path (aircraft electronics). Again, not sure how to make this work. I tried wiring in a diode, but it ended up not letting any sound through no matter which way it was facing or what wire it was on.

Any ideas?
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post #2 of 12 Old 06-18-2013, 11:15 PM
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It is pretty easy to build a circuit to do what you want but I suspect requires far more knowledge of electronics than you might have smile.gif. So here is an already built box that automatically switches inputs when it detects a signal. You can hook up your radio to that input and the other, to your music source; http://www.mcmelectronics.com/product/SPEAKERCRAFT-LL-ONE-/50-8385. Using this type of device also solves your problem of back feeding the signal into your aviation system.

It requires 12 volt supply which I am hoping you have in your 'copter.

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post #3 of 12 Old 06-18-2013, 11:27 PM
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Umm, is it legal to listen to music while flying a helicopter?

Just askin!

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post #4 of 12 Old 06-18-2013, 11:43 PM
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Quote:
Originally Posted by Glimmie View Post

Umm, is it legal to listen to music while flying a helicopter?

Just askin!
I believe they are allowed if they have the circuit he is asking about: i.e. giving priority to communication system.

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post #5 of 12 Old 06-19-2013, 12:03 AM - Thread Starter
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Indeed we are. Some aircraft have an AUX input built in, others don't. The ones that do, cut the music out when anything comes over the radio or when people talk to each other via the intercom. Sounds like that switch is exactly what the OEMs are using to make that happen.

That switch is exactly what I'm looking for, but the application is wrong. That would be something that I mounted into an aircraft permanently. I'm looking to modify the headset only. No modifications can be done to the aircraft, which also means I couldn't just carry that around and hook it up to the battery, and not all aircraft have power sources readily available to the pilot so an independent power source would be required.

You're right about me not being an electronics guru. I'm pretty handy with a soldering iron, but that hardly makes me an expert. Given the pieces to the puzzle I could probably put it together, but I'm definitely not about to wing it.

Now that I know something exists that does this (and what it's called), I'm looking around for something that will work for me but I'm not coming up with much.
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post #6 of 12 Old 06-19-2013, 02:48 AM - Thread Starter
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post #7 of 12 Old 06-19-2013, 08:11 AM
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Yeh, I figured you wanted something portable. The circuit is rather trivial for an engineer to design and build into a tiny box but is way beyond the scope of someone who is not. It also needs power but you can use a battery. I looked around for a while to see if I can find a kit, but could not. One idea may be to go to your local car stereo shop. They have the same need in that they integrate secondary audio sources that have to mute the standard audio system.

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post #8 of 12 Old 06-19-2013, 09:01 AM
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Quote:
Originally Posted by amirm View Post

It requires 12 volt supply which I am hoping you have in your 'copter.

IIRC, standard aircraft DC voltage, from Cesna to 7x7, is 28volts. Actually 24v battery voltage but 28v generator output. Just as in a car. 12v battery but 13.8v alternator output. Large passenger planes also have 120volts (115) with standard household outlets. But it's 400hz.

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post #9 of 12 Old 06-19-2013, 09:34 AM
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Quote:
Originally Posted by Glimmie View Post

Quote:
Originally Posted by amirm View Post

It requires 12 volt supply which I am hoping you have in your 'copter.

IIRC, standard aircraft DC voltage, from Cesna to 7x7, is 28volts. Actually 24v battery voltage but 28v generator output. Just as in a car. 12v battery but 13.8v alternator output. Large passenger planes also have 120volts (115) with standard household outlets. But it's 400hz.

If necessary, a device like this turns 28 volts into 12 volts:

https://www.sportys.com/Pilotshop/product/9060
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post #10 of 12 Old 06-19-2013, 10:18 AM
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Radio Design Labs (RDL) has a small modular device that will mute one signal when a second one (radio/intercom) is present. This is called "ducking". Getting 12 volts from 28 volts is quite easy with only a couple small components.

I think you have discovered that using a diode to mix sine wave (alternating current) audio signals is not an option.

Is there a DC power source available in the chopper? Such a device is relatively easy to build into a small enclosure. It would have a DC input, a radio audio input, and a music source input with separate gain controls for both sources.
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post #11 of 12 Old 06-19-2013, 01:29 PM - Thread Starter
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The particular model helicopter I'm flying right now is a 12v system. Like I said though, I can't modify the helicopter and there are no power sources readily available to me so a battery pack would be my only option.
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post #12 of 12 Old 06-20-2013, 03:53 PM - Thread Starter
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HA! I KNEW something had to exist! From what I can tell these don't provide any kind of delay between radio talk and mp3 resuming play, but it'll work.

http://www.aircraftspruce.com/pages/av/headsetx_adapters_cell_znon/pilotUSA26.php

There's a few other different ones out there at varying prices but that cheapo should work fine. Thanks for the help guys
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