Good Resources

EEVBlog 611 – Great video in a series of videos about microphones

Voltage Requirement

The characteristics of elect microphones are typically specified with a 2K resistor up to +5V. However you can power with a lower voltage. Many will work down to 1.2V, and some down to 0.8V (see the eevblog video) – it depends on the FET used in the mic.