Metal Detection Using An Inductor Instead Of A Clock Crystal.

This project from a few years back is an interesting take on a metal detector. Instead of building a detection circuit, [Bruno Gavand] replaced the external clock crystal with an inductor. Here you can see the inductor coil next to the PIC 12F683. You can see two components jumping from one breadboard to the other. These are smoothing capacitors on the inductor lines.

The watchdog timer for the chip is run by the internal RC oscillator. When the external crystal receives a pulse due to metal inducing a current in the coil, the value of the watchdog timer is compared to it. This data is filtered and if the proper parameters are present the green LED blinks. This is bicolor LED. If the inductor circuit is functioning properly it will blink red at power up. [Bruno] says that results will vary based on that inductor so you may need to try a few to get the calibration light to blink.

We’re thinking this would make a simple stud finder (by detecting where the nails/screws are in the wall). Check out the demo after the break, then let us know what you would use this for by leaving a comment.

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Autonomous Metal Detector Lets You Sit Back, Get Rich

thunderbird7-autonomous-metal-detector

As a kid, metal detectors seemed like great fun. Every commercial I saw beckoned with tales of buried treasure “right in my own back yard” – a bounty hard for any kid to pass up. In reality, the process was both time consuming and tedious, with little reward to be had. [Gareth] liked the idea of scouring the Earth with a metal detector, but he liked sitting and relaxing even more. He decided he could easily partake in both activities if he built himself an autonomous metal detecting robot.

He stripped down a hand held metal detector, and installed the important bits on to the front of an R/C chassis. An Arduino controls the entire rig via a motor shield, allowing it to drive and steer the vehicle while simultaneously sweeping the metal detector over the ground. He fitted the top of the rover with a camera for remotely watching the action from the comfort of his patio, along with a laser which lets him pinpoint the location of his new found goods.

Continue reading to see a short video of the robot in action, and be sure to check out his site for more build details.

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