untitled

Trying It Out..................................................................................................

You probably have a fortune in coins just waiting to be found at the bottom of

your furniture cushions, so it’s time you got this metal detector thing on the

trail of all those nickels and dimes! Here’s how to make this gadget work:

1. Insert the batteries.


2. Secure the lid on the box with the screws provided and flip the on/off
   switch to On.


3. Holding the coil away from any metal, turn the potentiometer knob so
   that the LED is on, and then turn the potentiometer knob slightly in
   the other direction till the LED turns off.
   This calibrates the IC so that it is triggered by small changes in the oscil-
   lating signal that runs through the coil.


4. Try out your detector by holding it near different items containing
   metal.
   We were able to detect coins and keys in pants pockets as well as vari-
   ous types of tools and nails at a distance of about^1 ⁄ 2 ". You should be able
   to detect larger metal objects (such as a space shuttle) at a distance of
   about an inch.

Figure 12-18:
The finished
metal
detector.

Chapter 12: A Handy-Dandy Metal Detector 299