LEMO adapter cable

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Rich
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LEMO adapter cable

Post by Rich »

As many are aware, the dual-plug headset jacks in most GMA340-equipped DA40s are designed to supply power to no-longer-available Sennheiser ANR headsets. This appears to make the feature totally worthless unless one goes to the considerable difficulty of installing LEMO sockets and tap that power line connected to the microphone jacks.

Not so fast, grasshopper.

I've determined it's feasible to fabricate a DA40 dual-plug adapter cable that supplies power to the LEMO plug from that existing dual-plug jacks.

Here's the overview:
The headset microphone plugs are physically identical to hand-held microphone plugs. The very tip section (of the three) is used for push-to-talk from such mikes. Headsets with the GMA340 neither need nor use this feature, yet standard dual-plug GA headset microphone plugs still have the three contact points and connect to the prong in the jack that is normally used for this function. It is this prong that has the DC power source connected to it in the DA40. I confirmed this today. So your everyday headset connector has 28 VDC sitting right on that tip piece of the mike plug.

Therefore a powered dual-plug <-> LEMO adapter cable is feasible. In fact dual-plug <-> LEMO adapter cables exist today, but do not claim the power-delivery function. It is likely they simply ignore this tip piece and don't bring the required third conductor from the mike plug to the required #1 LEMO pin. My mission now is to find out if there are any cables out there that (accidentally or otherwise) provide the necessary connection. Failing that I'll be hunting parts to fabricate one myself. This is useful to me as my BluLink-equipped stuff can be powered using A20 6-pin LEMO hardware.
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Tim H
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Re: LEMO adapter cable

Post by Tim H »

You've got me thinking, I wonder if you could pull the power off an unused jack and use it for a USB port?
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