For people who use the twin-jack headsets (the big majority) there is a Sporty’s pass-through adapter which extracts the audio, with a 3.5mm jack output which goes to a camcorder’s external mike input.
One can see it mentioned here (on the link on using video cameras).
My headsets are all Bose-plug type so I would need a different adaptor, which I have never seen. OR plug something into one of the unused headset jack sockets.
Some camcorders use a socket for a type of microphone called “plug in power” but I think that is just the cheap ones. The better ones will accept a line input. Currently I use a US-made “professional” miniature mike and a preamp which works very well, but one needs to always stick the mike inside a headset earcup.
Does anybody have a working schematic of an adapter from the 1/4" jack to a line level signal? It ought to be possible passively i.e. no battery.
Using one off the unused headset audio jacks seems the best way. They are a very common jack size (unlike the Mic socket) and its trivial to get an adapt to change it to 3.5mm that nearly everything uses these days.
Some years ago I made one for a “plug in power” mic camcorder. All I did was solder a resistor divider (actually, a small potentiometer and resistor – and twiddled the potentiometer till the sound recorded on the video tape no longer distorted) inside a 1/4in. headphone jack housing. Not exactly “the right way” to do it but it worked well (and obviously didn’t load down the intercom).
Many thanks… I did a google and found this
which at least tells you which of the three jack plug terminals to use, but what does the battery do?
The same circuit appears on other sites e.g. here (that one has a completely wrong explanation for the two electrolytic caps back to back) but with no explanation for the power.
I suppose the batt is to energize the electret/condenser microphone in the aviation headset.
I am looking for a thing which plugs into the 1/4" headset socket and extracts the signal from that, while next to that socket is the 6-pin Lemo Bose X/A20 socket into which the headset connects and which has +28V wired to it already, so the headset side should be all taken care of.
Especially as an ANR headset needs power so whether its mike needs power supplied via the (smaller) mike jack plug is possibly a moot point. Actually it would not surprise me if a headset like the Bose did just use a dumb mike which needs the power via the jack plug, and then it will work even with a flat battery, and will work in the twin-plug version. But as I say this angle must be taken care of via the Lemo plug.
That circuit is for connecting microphone of an aviation headset (possibly electret) to a computer. Not for connecting headphone output of an aviation intercom to a line level input of a recorder.
As an aside, Sennheiser offers some headsets that take power for ANR from the microphone socket and AFAIK Diamond wires their planes for this from factory.
Peter are you not making this more complicated than it needs to be?
Presumably what you are trying to record on has a 3.5mm line in jack?
Then isn’t all you need one of these
Link
Plug it into a audio jack for a headset (one that isn’t being used) and use a 3.5mm to 3.5mm cable to go from there to your recording equipment?
It turns out I looked into this when building this Lemo plug to ICOM twin jack converter, about 10 years ago.
But that shows a mono 1/4" jack. I must have drawn it that way for a reason, presumably because the ICOM used a mono jack socket. Do current headsets use a mono jack? The current Bose A20 certainly seems to.
It is very possible that a 1/4" to 3.5mm converter is all that is needed! Probably with a resistor mixer (2 resistors) then a pot (say 10k) and feed both channels of the 3.5mm camcorder plug from the wiper of the pot. There is nothing to gain from having it in stereo.
The current Bose A20 certainly seems to.
The picture you circled actually shows a stereo jack…
But yes most aircraft installations I’ve seen are mono…
