Chapter 12
Chapter 12: A Handy-Dandy Metal Detector ...............................................................
In This Chapter
Exploring the detector circuit
Checking off the parts list
Assembling the handle
Mounting the circuit to the handle
Finding metal!
F
inding little bits of metal is a time-honored task, right up there with find-
ing free music to download off the Internet. With a metal detector, you
can scout out coins in your couch, nails in your walls, keys in somebody’s
pocket — face it, the applications are endless.In this project, we show you how to build a small, handheld metal detector
that can detect certain kinds of metal — especially ferrous (iron-containing)
metals — even if that metal is under a half-inch or so of drywall, sand, or soil
(but never water!).The Big Picture: Project Overview.............................................................
In this project, you use an IC that generates an AC signal that goes through a
coil. Because metal objects conduct electricity, you can induce a current in
those objects. When the coil in the metal detector comes near a metal object,
the electromagnetic field in the coil induces currents in the metal object. The
electromagnetic field generated by the metal changes the current in the coil.
When the signal changes, IC turns on an LED, alerting you to the presence of
metal.You can see the finished metal detector in Figure 12-1.