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.

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!

Thanks. Will give it a go!

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)?

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.

Got a newbie question. My boss dug up a mini jack to 1/4 inch adapter for a lav mic, (very similar to the Eagle mic that Sunray posted). Takes an LR44 button cell and has a switch for the power. Had a root inside and it has a Capacitor and Resister circuit buried behind the switch. Capacitor is 225C 2.2UF 16V Type A 3216 1206 Piezoelectric and the resister is 3 red bands so 2.2k. Can I simply splice that into the cable above the existing capacitor and resister, (those shown in the photo directly attached to the pin of the xlr connecter) or will that cause me problems. Working out the easiest and least potentially distructive way of testing this out.

Any ideas on the battery placement considering the location of the cap and resister?

Looks to be red, black, orange and possibly gold.

Had a better look at it today at work under an eye loupe. The resistor actually bridges the legs of the capacitor legs rather than being inline. Have redone the illustration to correct it.

Please excuse the layout. Hope its clear enough. This is what seems to be happening.

So I had a hunch and unscrewed the XLR connector on the headset. Turns out there is already a capacitor and resister on the mic pins. Can't quite get a good enough pg=hoto with my phone and my eyes are not good enough to read the figures on the cap. Would I have to inject the 1.5v above the capacitor, (between the mic and the capacitor)? Would I need anything else in the circuit? I could put a battery holder inline with the cable if that would work which mightl be simpler and much more streamlined.

Possibly is the answer to bits access! Between a rummage through my Dads garage, colleagues in the theatre and Ebay I'm sure I can rustle them up now I know what I am looking for. Have a shiny new soldering iron in my Stage Management kit, (for small things like fairy light repairs) which can get exercised. HAve a shift on Sunday morning babysitting a church group so will have four hours to chat the circuit through with my boss. Will report back when I have something physical!

Thanks Sunray! Have spent hours on Google trying to find solutions but as a lady I worked with once said, if you can't read music it's just fly ###### on paper!! Sadly my lack of knowledge meant I couldn't weed out the relevant info from all that was available. The heads up and help on here has been very useful. I can't claim to fully understand the schematic but at least I know that once I have translated it the info is relevant. That will be my Sunday morning sorted.

Seems I overestimated my understanding!!!! Thanks for the corrections and the link to the article. Interesting read.

Hi Sandall, I'd say that I can follow the logic of how something works if explained but don't have the technical knowledge . In this situation for example I understand that the mic needs power to operate and that logically a small box injecting the 1.5v into the line should do the trick. I also understand from some research that the use of a capacitor to block unwanted phantom power entering the circuit and damaging the capsule. I also get that because of the way the electret generates the signal its is "quiet" and may need boosting before entering the comms in order for people to hear me. Now how that all works actually works is a bit of wizardry involving the magic smoke. If this all works I have an ultimate goal of getting a bone conduction headset with bone conduction mic working!! It is designed to work with a motorola or similar radio so in theory should be possible and would help prevent the show monitors injecting back into the comms which kills me!!! Any suggested circuits or help/practical solutions always gratefully received!

Thanks for the info so far. Not sure how sensitive the packs are. Only figures I am sure about are those for the Pointsource headset and the 1.5v to drive the mic which came from their tech department. Have a version of the Clearcom MDXLR4M adapter which takes a standard dynamic 4pin xlr headset and interfaces with a DX series wireless beltpack. AS I mentioned the nuts and bolts theory of it I understand but my electronis understanding doesn't go much beyond not letting the magic smoke out!!

Hi all, After struggling with lightweight headsets in noisy shows I have purchased a Point Source CMI5 headset. My issue is it has an electret mic that needs 1.5v to drive it. I would like to b able to use it with both wired and wireless systems and the idea is to build a small interface module that sits on the end of the cable and accepts an AA battery and injects the bias into the mic line. This will give me the benefit of having adapter cables for different systems, (4pin xlr for wired comms and an HME mini din adapter for DX series wireless etc) As far as I can make out it needs a cpacitor to block and DC power coming from the beltpack that is potentially damaging along with a resister to bring the impedance of teh mic from 1500 ohm to around 200 ohm????? Sorry to say that beyond that my understanding of the electronics is not up to understanding what components are required. Could anyone point me in the right direction or provide an idiot proof diagram with simpleton labels for those not electronic symbol literate. Any help most gratefully received and will of course share files, results etc to anyone interested upon successful completion of the project. For reference the headset I have is here https://www.point-sourceaudio.com/products/intercom-headset/cm-i5/ scroll down to the bottom and select Specs for the full spec.