This is my latest Circuit published in the June 2015 issue of Electronics For You Magazine. It is a device that measures the intensity of Radiation in the room. Lot of Electromagnetic radiations are present in home emitting from WiFi, Mobile phone, Computer and other electronic devices. So the device shows the level of RF energy in a meter. Meter shows full deflection when the RF radiation is very high. It also gives a simultaneous LED indication.
See the working of the circuit
Radio Frequency Detector