How to Build a Kid's Metal Detector

Help your child find buried treasure with this simple metal detector.

Searching for "buried treasure" with the aid of a metal detector provides hours of family fun in addition to teaching kids about radio frequency. Unfortunately, many commercial models are expensive and difficult for children to use. Instead of spending hundreds of dollars on a high-tech toy, try making this easy to use metal detector out of household objects.

Things You'll Need

• Pocket calculator
• Battery-powered, portable AM or AM/FM radio
• Pencil
• High-temperature hot-glue gun

Instructions

1. 

   Small, portable raidos work best.

   Tune the radio to the highest AM frequency that does not contain a broadcast station. Turn up the radio's volume so that the static is easy for your child to hear.

2. 

   Small, flat, battery-powered calculators work best.

   Turn on the calculator. Position the calculator and radio back to back so that the radio's static changes into an even tone. Turn off both devices and mark the calculator's position on the radio with a pencil.

3. 

   Be sure that your hot glue sticks are labeled "high temperature" to ensure proper bonding.

   Use high-temperature hot glue to join the two devices together, using your pencil marks as a guide. Let the glue cool for five minutes; then erase the pencil marks.

4. Have your child test the metal detector by turning on both devices and moving them, calculator side down over a metal object like coins or a fork. The radio's static will produce a high-pitched beep that becomes more intense as it gets closer to metal.

5. Explain to your child that the the AM band of the radio picks up a weak radio signal emitted by the calculator's circuit board. Metal objects reflect and intensify this signal back to the radio, thus producing a beeping sound.

Tips & Warnings

• Use duct tape to fasten the detector to a boom handle so that your child can hunt for metal objects without straining his back.

• Children should only use high-temperature hot glue under adult supervision.

References

• Downtown Club: How to Make a Metal Detector