external power source--also known as phantom power...
usually either having a battery or a current supplied
through the microphone cord...for this i believe it is
necessary to have XLR connections...with 3 prongs...
a "phone" or "phono" input plug probably will not suffice
for power transference.

good luck and let us know what you find.

is this a cassette recorder, or disc/mini-disc?

some have optical inputs which is not a mic at all.
this is just for down loading an already recorded
signal...presumably already digitized...

radio shack has some condenser mics with battery
but one i have turned out to be monaural..no stereo.