48v phantom, battery powered

[Freq Band]

I found this circuit years ago, printed it, but do not know the author's name.
If you know, let us know.
There is text explaining the circuit, and I'm too tired tonight....but it does work.
Unfortunately, I misplaced the unit I built, before I could run a battery life test with a real mic setup.

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[moamps]

http://www.groupdiy.com/index.php?topic=12807&postdays=0&postorder=asc&highlight=phantom&start=15

 

[Freq Band]

Wow, how did I miss that post ??

That thread was even started ...by me !!


--Anyways, the above is a more readable schematic than the source found here:
http://web.telia.com/~u31641623/48%20V%20phantom%20from%209%20V%20battery.jpg


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[bcarso]

One thing that bothers me a bit is the low operating frequency. It's appropriate for bipolars I suppose but awfully close to the audible range.

Another thing is: sometimes those cross-coupled multivibrators won't start.

 

[Freq Band]

24 kHz ??
...or the 12k harmonic ?

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[zebra50]

Maybe not quite as exciting or fun to build, but my approach for battery phantom is just 5 x 9V battery in series!

 

[Rossi]

2.5 mA is a bit lowish for most modern condensers, let alone two mics for stereo recording. I feel more sympathy for Zebra's 5 x 9V solution. Adding a lytic across the batteries may be a good idea; battery power can be noisy.