Solder your own Bionic Ear that allows you to pick up the quietest sounds using the principles of a directional microphone.
Learn about circuits and construct a working listening device.
Includes a beginner level soldering iron- quick heating and cooling, usb cable, solder wire, pc board, 3x test resisters. Bionic ear- 38 pieces, headphones, step by step instruction book
Requires 1 x 9-volt square battery (not included)