Hi,
I am having lots of remote meetings and wanted to be independant of a cable. First thought is to connect a bluetooth headset but bluetooth is and will stay blocked by the company owning the device which is a nano pc.
So I am looking for a combination of headset (best would be mono like jabra motion) and a base station offering a simple plug 3.5mm 4-pin in order to connect to the nano pc.
Do I have a chance? Where?
Happy and grateful for any hint!
Oliver
I guess they won’t suit you because you probably want the microphone on the same cable as well?
TP-Link HA100
Mozos B2
Audiocore AC830 or Audiocore AC820… apparently they have the ability to change the direction RX / TX
1Mii B03 Pro
1Mii B310 Pro
1Mii B03Plus
1Mii B06
1Mii ML300
Or if you have a free smartphone that has a 4pin jack and bt, you can try to connect the handset via bt to the phone and on the phone using some app to mix and output the jack.
I’m not sure if Android can do it… not to mention the appropriate cables.
Alternatively, instead of a phone, just some pc / lap / sbc on which you will do a signal mix and give it to BT and jack.
You can split one 4-pin into two jacks with any cable / adapter and then connect it directly to the computer. The handset, of course, via BT. And connect everything with a mixer and mix the sources …
I did a quick little test and I don’t think such a tangle of cables will work, especially below Android10.
I simulated your nano pc with a Tablet, from which the sound was output through the jack and fed to the phone to the usb sound card to the microphone plug.
Audio routing done with LesserAudioSwitch and listening quickly with the Microphone app.
The signal input is set to DAC / USB, but it will also work with the jack / headset, although I had a weaker signal. The output is set to bluetooth. BT headphones with microphone attached to the phone, mono / stereo does not matter …
App Microphone turned on and captures input / microphone signal.
The end result… I can perfectly hear the sound coming from the tablet (nano pc).
In other words, the people who would talk to you during your calls would be heard through the bt earpiece.
But the same will be accomplished perfectly simply with one of these transmitters mentioned above. So the $…
But this is only half and this is obvious to everyone. The problem is, however, send the voice from the bt microphone to the tablet jack (nano pc). I have struggled with this for a while and I don’t see simple solutions, apparently A10 and above can touch the source twice, in the case of lower versions I fail.
Yes, you can set the in / out so that you can catch the bt microphone, but then you will not hear others’ voices. One or the other both on something like A7, A8 doesn’t work.
You can of course make a crazy move and go completely commando into battle. 
Two Android devices, separate BT microphone, separate BT headphones.
One set does as input audio and the other as output audio. They work completely independently of each other, but it should work. one point of contact will be the split on the 4P jack cable going into the nano pc. On the nano pc side, there will be no difference, it will still be a standard 3.5mm 4P input / output jack plug.
Or, instead of Android, there are two ready-made devices. One transmitter and one receiver, the rest remain the same. Very stupid, I know I know…
The easiest way would be to find a box that will attach itself to the headphones, but at the same time will be able to pick up the microphone. but if I understand correctly, even these double tx / rt must be set manually and I have doubts whether they are capable of handling the microphone.
It is much easier to do it on a normal machine with normal OS and full in / out control.
Thank you Tim! I am astonished about your interest and creativity. Very good ideas! I think I will try the approach with the laptop first as it is always available anyway. I will come back with my results, but this might take a while as I am very busy at the moment. Thanks so much
I asked one source that sells a lot of 1Mii equipment and the source confirmed the fact that these devices are only one directional, so they are not able to handle the microphone. I thought so too from the beginning. You can select the TX or RX operating direction, but not duplex transmissions. It would be okay to listen to the voice of your talkers in the handset, but the microphone will not work.
Probably the easiest way to go with the laptop. You just need the right cable…
One side is a single 4pin male jack (for nano pc).
On the other side, there are two male 3pin jacks (for a laptop sound card).
I did another test… Laptop with windows 10 and “nano pc”.
I used the “Voicemeeter Banana” software.
From the “nano pc”, the 4pin jack separated into two 3pin laptop jacks.
Windows 10 should have properly active devices such as an integrated sound card, i.e. speakers / headphones and a microphone.
The second device is bluetooth earphones both out and input source.
Then in VMB we set similarly as below…
The philosophy is that the hard-input from the microphone bt must be transmitted to the sound card (speakers / headphones jack).
The hard-input from the card’s microphone must be broadcast to the bt earphones.
And in windows the BT device must be set as the main source of sounds in the OS.
End effects… I hear sound from nano pc in bt earphones.
The voice from the bt microphone is heard on the nano pc.
The sound quality is so-so but you can use it.
And that will probably be the end of this adventure. This way you will achieve exactly what you wanted from the beginning!
Once you decide to take the next steps, let us know how the story ended.
And what if I want to use on laptop side and on nano pc side both a 4-pin cable? Which pins would I need to switch? The laptop has only one plug but if necessary I could use an adapter usb left and two 3-pin plugs?
Two Cables: One Male 4Pin Jack to Two Female 3Pin Jack.
Two Cables: One Male 3Pin Jack to One Male 3Pin Jack.
Careful with that purple plug!
As described here, tip or ring (or both) on the Mic-Jack carry “phantom power” which may slowly (or quickly) roast the output-stage on the Audio-sending device.
The whole set is a guerrilla with ho ho…
It is a simple cross link sending an analogue between two sound card. We serve audio from the laptop (headphones / green) to the microphone in the Nano PC and vice versa. We play in the pretend that headphones with a microphone are connected to both machines, only in the middle we make a crossover connection. Perfect? Not.
But in theory it should work. Can you do better? You can, but the plan was as simple and fast as possible.
And if there is a concern about voltage, you can go in the direction of the USB - Jack adapter. But I don’t know if the OP wants… 
The original post did not involve usb and only mentioned the jack.
PS
I hate 4pin!
Yeah, I got that part. And that part of the criss-cross is the bad part. Feeding voltage in where voltage is expected to come out is less than ideal.
Like hinted at above, not sure it will.
The two big concerns:
Backfeeding a DC-supply into an Op-Amp or Audio-Codec Chip.
Shorting Left and Right audio channel.
I hope so:
10kΩ on the outputs for audio. If there is impedance sensing going on on either end, this should ensure Line-Level voltages.
47kΩ Pulldown for the combined L+R audio.
Capacitors to couple only the Audio into the Mic-In and block the DC provided by the Mic-In to backfeed into the audio outs.
Missing: Any regulation on the audio out since Mic-Level is a lot lower than Line-Level and may just distort and clip.
Same.
I already tested as much as I could and it works, on a living organism… Another thing, vitality after weeks / months / years, but that’s another matter…
Nice scheme and everything, but deliver it to the OP in the form of a ready-made solution for low $ to buy.
Sorry for being confusing. I proposed the USB adapter on the laptop side just as a fallback. But you gave the perfect solution for the 4-pin on both sides. Thanks a lot!
Good - Cheap - Easy
Pick two.
In the past, the sound was mono, and two-pin or TS connectors were used. Today they are hardly used anymore, only on outdated equipment and mostly not for listening, but for recording
Try Jabra Evolve 40 with USB
