DIY phantom power + pictures

[Janke]

OK, I've mentioned this before: You need 3 resistors, two capacitors and a small battery to power a condenser mic that needs, say 9 or 12 volts. Here's how I did it:

1 - schematics: http://tinyurl.com/phantomschem - upper diagram for unbalanced input, like on the HVs. Keep cable short - mine is just 10"...

2 - the actual electronics, assembled on a narrow piece of breadboard, with a 12 volt battery that will fit into an "elongated" XLR plug... use whatever is handy for the elongation, I had a piece of conduit tubing (not shown) that I split and put around the circuit board, and fixed everything with electrician's tape. Quick-and-dirty, but it works! No power switch is needed, just unplug from mic and battery won't run down...

This works well with the T.bone 9900 shotgun I just bought.

[drapeama]

...to power a condenser mic that needs, say 9 or 12 volts.

Is the usual "11-52V DC" of, let's say, an AT897 can be powered with this? And it terminates a balanced signal, that's pretty cool.
You ended it with a 3.5mm terminal, can you do it with another XLR plug? I guess you can make some kind of "module" from this to provide more power to a more consuming microphone.

Pretty cool info shared Janke! Thanks a lot!

[Janke]

Yes it can, but the AT897 has an internal battery, so why use phantom power?

My t.bone has no battery, and is specced 9-52 volts. Some mics actually want 48 volts, and in that case you'd need a lot of batteries...

If you want another XLR plug, then you should use the lower schematic, which is balanced. An added benefit is that the cable can then be longer without risk of interference.

One more thing: I've used a small 12 volt A23 battery with only some 50 mAh capacity. It will power my mic, which draws 2 mA, for only some 20 hours. Check your mic specs! You need to remember to pull the plug from the mic when not in use. Puling the camera plug won't stop draining the battery.

Here's some info about the battery: http://en.wikipedia.org/wiki/A23_battery

[drapeama]

Just to keep it alive so others can read it, as it's really clever and can be very useful.

[drapeama]

Just thought this thread should have been in the stickies before that.
Still, it's a little something that could solve many problems and would probably be way cheaper to DIY rather than buying one, although one has only one input as the other has 2.