OT: Phantom Powered Opamps

[kdawg]

my first post for you current/voltage savvy members...

I'm trying to figure out if you can power a pair of LM386 opamps and 1 LED off of mic XLR ~48V Phantom Power. According to specs, an LM386 can run from 4-12V. Current draw is ~4ma at 6V I think.

Anyone have a small schematic on their brains, if this is possible? I'm a little concerned about varying phantom power supplies, as I've seen everything from 9V to 48V.

thanks!
-kdawg

[Peter Snowberg]

You could do that with a switching regulator which would adapt to a wide range of voltages. Is it possible? Yes. Is it straight forward? Well.... maybe not so much.

I would start looking at switching regulators at http://www.linear.com

Linear Technology has Application Notes and they have Design Notes. Check both. They will probably have something all ready to go.

Look for circuits that run at frequencies that are WELL ABOVE the audio range to avoid squealing issues.

Could you give some more details of your application?

Take care,
-Peter

[kdawg]

I'm putting together a headphone amp for stage use, and I thought how nice it would be to do away with a battery and/or power supply since there is phantom power available all around from mic cables.

Here's the schematic (headbanger amp): http://www.minidisc.org/schem.gif

Thanks

[puretube]

I`d be worried, if the phantom-power-supply can deliver enough mA.
Your example says 4mA@6V (=24mW, which is not much for studio-use),
this seems to be idle-current (no signal/no output).
When driven to normal volumes, the headphone-amp would (want to)draw
much more current, which not every phantom-supply is able to deliver...

[spongebob]

HeadWize is the best place for headphone related stuff, they have some nice headphone amp projects, I built the Pocket Headphone Amplifier a while ago, really nice! It's battery powered though...