#3. "RE: Nikon D7000 powered external mic output" In response to In response to 0
St Petersburg, RU
I have read conflicting descriptions of that mic. B&H calls it s Dynamic Mic when it is clearly an Electret Condenser mic. The D7000 does not supply voltage to the FET built-in reactance to voltage converter that changes a dynamically changing capacitance to a changing voltage. The electret mic element itself has a permanently charge on the element but the FET converter needs about 1.5volts DC between Drain and Source terminals which the D7000 does not provide. The current drawn is not much higher than the leakage current of the battery itself so a battery will last a long time. Higher voltages can be tolerated however and the results include higher output level.
You can make a power adapter for larger batteries if you to, by building a small circuit with a AAA cell or 2 in series for 3 volts. Parts list: 2 metal film resistors(for low noise) any value between 2K and 18k 2 1-10mfd Electrolytic capacitors. 1 TRS 3.5 mm phone plug(stereo plug) 1-2 1.5 volt AAA or AA batteries 1 Battery holder 2 TRS jack(stereo phone jack 3.5 mm) 1 small plastic box to house the battery, resistors and jack 1 Short length TRS to TRS 3.5 mm plug to 3.5 mm plug jumper cable. The length depends on how far from the camera do you want the adapter box(shorter the better)
A. Mount both jacks in the plastic box.Label one of the jacks "Mic In" and other "Output" B. Connect a jumper wire between the ground terminal of the two jacks. C. Connect the capacitor's Positive wire to the Tip of Mic-In jack and the negative wire to the Output jack. D. Repeat by adding the other capacitor's positive wire to the Ring connector of the Mic In jack. E. Connect one lead of a resistor to the Tip connector of the Mic-In jack. This will be the FET Drain load, to develop the output voltage across the load resistor. F. Connect the other resistor wire to the battery holder's Positive(+) terminal. G. Connect the second resistor to the Ring connector of the Mic-In jack. H. Connect the two loose ends of the resistors together and connect the positive wire of the battery holder to the junction of the two resistors. I. Connect the negative battery holder wire to the wire that connects the two jack's grounds together(added in Step B).
For use, plus the mic cable into the Mic In jack which connects the battery. When not in use unplug the mic and no current will be drained from the battery. Connect the TRS to TRS jumper cable into the Camera Mic in and the adapter box Output jack and it will be ready to work. Mount a strip of Velcro on the camera strap and glue the hook mating surface Velcro to the back of the adapter box for easy use or removal.