For anyone who ventures into the land of mics and audio equipment I am providing a link to one of the best websites I've found over the years.

http://sound.westhost.com/

The articles are informative and there is some mic info buried in there in addition to a couple of articles expressly about mics, the power supply, and amplifiying the signal. For those who don't have an electronics background, I'd suggest that if you decide to move into building any of the projects that you work with someone who does. You're not likely to kill yourself, but mistakes can be costly when equipment starts to issue forth billowing clouds of distress which could have been prevented with proper bench testing methods.