Fires high-energy magnetic pulses and measures the decay time of target eddy currents. Deep treasure hunting, gold prospecting, saltwater beaches.
Demystifying industrial and consumer metal detection circuits via hands-on schematic analysis.
: The authors cover a wide range of detector types, including: BFO (Beat Frequency Oscillator).
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: Detailed explanations of magnetics, induction, and eddy current responses—the core phenomena that allow a detector to sense metallic objects.
They are not just writers; they are the people who actually designed the circuits that treasure hunters have used for decades. This means the book is grounded in real-world application, not just theory.
A metal detector is only as capable as its antenna system. Inside the Metal Detector devotes significant coverage to the geometry, shielding, and construction of search coils:
, the forum's lead engineers, weren't just searching for buried treasure; they were building the maps that would let others find it.
The primary resource for information, design files, and community projects related to this textbook is the Geotech Forums , an online hub co-administered by the authors. Core Engineering Principles
The PDF version of "Inside the Metal Detector" is a valuable resource. Here’s why:
The earliest, simplest form of detection architecture. It utilizes two RF oscillators to detect target presence via minute changes in frequency.
Overton and Moreland break down how VLF systems separate a target’s inductive properties from its resistive properties using phase demodulators. This allows the system to differentiate between ferrous items (like iron nails) and highly conductive non-ferrous metals (such as silver or copper).
Inside the PDFs is a heavy focus on coil construction. Overton favored mono-coils (transmit and receive on the same coil), while Moreland experimented with "bucking" coils (DD style). Their documented tests show exactly how to wind a quiet 10-inch coil using a hot glue gun and a plastic former.
The standard for modern coin and relic hunting. VLF systems analyze phase shifts to determine target composition and ignore ground mineralization.
To understand the book, you must understand the platform that made it possible: . Founded by Carl Moreland, Geotech is widely recognized as the single largest collection of metal detector information on the internet. It serves as a central hub for technical discussions, open-source projects, and a community of dedicated enthusiasts.
A practical project to build a highly sensitive probe for isolating targets within dug plugs.
Many hobbyists keep both versions because the projects in the 2nd edition are not repeated in the 3rd. If you're planning to build one of these, let me know: