receiver circuit for 433.92 MHz data transmissions, uses ASK modulation, based on T7544 IC
http://www.spelektroniikka.fi/rfirkytkis.htm#ask
provides more than 60 dB of dynamic input range at 150 MHz
http://www.edn.com/archives/1996/101096/21di_08.htm
super-regenerative receiver's sensitivity is better than 1 mV, and it operates over a wide range of VHF
http://www.edn.com/archives/1994/010694/01di4.htm
http://hem.passagen.se/communication/quadcoil.html
activates a variety of devices when your cellular phone is in use.
http://www.wenzel.com/pdffiles/cellhelp.pdf