Build a Laser Spy Microphone

Figure 1 

This tutorial wont be the most practical recording setup you have ever used, but it is an interesting bit of science and a great DIY project.

It is a simple laser listening device that will allow you to listen inside of buildings hundreds of feet away from you. The process involves a simple bit of soldering and all you will need is a laser pointer, tripod, and old pair of headphones, photocell and a recording device.

When an electric current passes through said diaphragm, the output forms a complex signal which can then be interpreted by a recording device as sound. It can record sound through windows with a laser pointer and cheap parts you can find at any electronics store.