Comms headset bias power circuit help

[thepurser]

it's a mono jack.
Apparently the adapters came with a load of lav mics the theatre purchased years ago so will see if I can get my hands on another one to sacrifice for a deep dive inside.

Sorry for the poor pictures.  Resister colours look odd but under strong light they are all red. Colour seems to depend on the amount of reflection hitting the curved surfaces.

[sunray]

Can you confirm the track layout for me please, I can't quite see the edges

If it is correct, I believe I see this

Which is a new one on me but looks to be perfectly functional

I have every expectation this is a working solution except your existing resister (shown brown) will need to be reduced in value or even deleted.

[sunray]

deleted

 

Edited August 27, 2022 by sunray
confusing reply

[thepurser]

The track layout seems correct.

So, in your opinion would it be better to remove the original capacitor and resister and just insert the new circuit?


If I understand right you are also suggeting to bridge pin 1 and 3, (both grounds)?

[sunray]

25 minutes ago, thepurser said:

The track layout seems correct.

So, in your opinion would it be better to remove the original capacitor and resister and just insert the new circuit?

Without knowing the full spec of the headset (drawn a bit of a blank on google), I'd say cobble it together like this

and see what it does, after that I'd be expecting to reduce the value if it 'nearly works'. Typically by half each time, ie 10K - 4K7 - 2K2 - 1K

Sorry no. That was silly of me  to introduce here, it simply reminded me of another product I own and had never thought about how it works, I've deleted it to save confusion.

Edited August 27, 2022 by sunray

[thepurser]

Thanks. Will give it a go!

 

[sunray]

As a matter of interest, how does this thread compare with a Neutrik plug body?

[thepurser]

Will have a look tomorrow when I get my hands on one of the spares! At first glance it looks close but almost certain it's just out!

[sunray]

2 hours ago, thepurser said:

Will have a look tomorrow when I get my hands on one of the spares! At first glance it looks close but almost certain it's just out!

I'll keep my fingers crossed🤞

[thepurser]

Grabbed a spare xlr and as suspected its about the thickness of the housing off.
Nice idea though.
Just need to pluck up the courage to do some soldering of very thin wires now.

 

[sunray]

3 hours ago, thepurser said:

Grabbed a spare xlr and as suspected its about the thickness of the housing off.
Nice idea though.

 

That's a shame.

[addo_00]

It's probably easier to rekindle this thread than start another!

I'm looking to do the same thing as OP - I'm hoping to use a headset with an electret mic with a beltpack that expects a dynamic mic, usually that would be a Tecpro beltpack.  It's rare for the companies I work for to use posh comms unless there's an external sound company involved.

I'm hoping to use a Riedel Run Headset. 
Before I found this thread, I had  been looking around all over the place to find a circuit that I could buy/use just so that I could pop it in a box with the necessary I/O cable connections.  I've seen various boards for sale on Ebay that look like they might fit the bill, but they all seem to list themselves as preamps so if I went down this route I'm guessing that I'd need to probably pad the output down 40db as it would otherwise be a too high a level for the beltpack?  These boards also have an adjustable output - In my mind that sounds like a useful feature (forgetting about the level being too high) as then I could turn the mic down so as not to be too loud for the other comms users.

I'm not sure if I can add links to the boards on Ebay so I won't, but I searched 'Electret bias voltage adjustable gain' and the ones I'm looking at were some of the red coloured boards.

For the power source, I was planning on using a 9V battery but is there any reason to use a lower voltage? On the spec sheet the operating voltage is 3-10V but could I, for example, get away with using a couple of AA batteries instead?

If the boards I've mentioned above aren't suitable is there other methods of getting the mic voltage biased and with an adjustable output - does anyone even think an adjustable output is necessary?!