Simple amp I can build in a day

[skyler]

I need to amplify microphone level audio (not electret, just AC) to small portable speaker audio levels for a portion of a birthday present I need to create in a day.

The audio will come from an induction pickup coil, and I want it to pick up the slightest signals, like the hum from an AC line in a house.

Is there a simple circuit from parts from RadioShack that I can build? I would like it to be DIY, and not just buy the amplified speaker they have.

Thanks