Telephone amplifier schematic? Answered

Hi, I saw this cool thing on Make; an instrument that picks up remote signals and makes noise.
This link shows the original product:
http://www.moonmilk.com/2010/02/04/instrument-a-day-4-remote-interference/

I hear the product is a telephone amplifier with a coil as an input. I would like to know if there is a schematic for the amp that someone new to electronics could work on. Its really interesting stuff.

Thanks