This idea is both for indoor and outdoor use, depends on how you could modify or enhance it. The important reason you ought to build this circuit is to learn building non-ic oscillators, this trains you on L, C, R and Transistor Switching. – delabs
With a handy metal detector you can check beforehand whether there are metal objects in a wall, ceiling or floor. An LED indicates if a metal object is in the vicinity and keeps your simple home projects, simple and safe.
Avoid disaster when drilling at home By Ben Godfrey
Ben Godfrey is an electrical engineering student at the University of California, Davis. Ben has written iPhone applications and is a Ham Radio operator.
See also – Metal Detector Circuits Problem