Build the electronic "bug" swatter. RF sniffer can locate minuscule RF signals from just about any source, including eavesdropping devices, leaky microwave ovens, RF interference, etc.
HANDS-ON ELECTRONICS Aug 1988 (v.5#8) pg. 75
Correction HANDS-ON ELECTRONICS Jan 1989 (v.6#1) pg. 4
Microwave leak detector. Simple circuit uses only a microwave diode and an LED.
MODERN ELECTRONICS [2] May 1985 (v.1#8) pg. 53
Facts you should know about microwave ovens before you buy one. Includes plans to build a low-cost meter to spot microwave leakage.
POPULAR SCIENCE Feb 1973 (v.202#2) pg. 79