LEMO Connector Question

[Pat Hatch]

I did a search on the LEMO connector and didn't see much on it. I am upgrading to a Zulu headset and want to re-wire for the LEMO option which will combine the phone, mic and power functions. Currently I have a battery-powered Lightspeed 3G 30 with separate plugs for phone and mic. I am trying to decide whether to make the power pin "hot" or wired through the master. I am looking for input on which would be the better way to go. Anyone have any thoughts on this?

[nucleus]

I would wire it to the avionics bus, the headset is little use without the intercom and radios.

Hans

[roee]

Originally Posted by nucleus

I would wire it to the avionics bus, the headset is little use without the intercom and radios.

Not quite true. As far as I know (at least for the earlier Lightspeed headsets) the battery-supplied power is used to operate the ANR only. The audio speakers and mic operate independently of the ANR and do not require battery-supplied power.

If you like, you could still wire it to your avionics bus (if you have one at all, but that's a whole different discussion). But then understand that when the avionics bus is off, your ANR will be off, and you will have a very noisy experience. If you're willing to live with that, then I don't see any other problems.

Originally Posted by Pat Hatch

I am trying to decide whether to make the power pin "hot" or wired through the master. I am looking for input on which would be the better way to go. Anyone have any thoughts on this?

I would not wire it to the "hot" battery bus, because if you leave your headsets plugged in and forget to turn them off after flight, you'll be draining your battery.

The master bus seems like a reasonable option. Same caveat as with the avionics bus. No power = no ANR.

With either master or hot bus option, I would want to know that the power supply circuits in the headset are robust enough to take the voltage fluctuations that they'll see during engine start (they should be, but that would be a good question for Lightspeed). Otherwise, you'd want it on a switched circuit.

[Pat Hatch]

Thanks, guys. I think the issue for me is in the case of an alternator failure, whether or not to include it on the essential bus which, for me, includes only those items needed to make an instrument approach and land asap. Or in the case of good weather, possibly making it home on the battery.

My understanding is that ANR power shuts off automatically after 2 minutes, which would argue for the hot battery case, but I really don't like wiring things directly to the battery. Voltage range is 8 to 40 volts, so I don't think transients would be an issue. Power drain is probably minimal which would argue for putting it on the essential bus, but I think I'll put it on the non-essential bus and just consider the ANR a nice-to-have option, but not essential. Unless someone raises an issue I haven't thought of yet...

[IowaRV9Dreamer]

Does anyone have a reference to the correct LEMO connector to install, and what the wiring diagram looks like?

Thanks!