Metal detecting for gold nuggets requires a bit of preparation before successfully finding gold nuggets can be done. First consider the following metal detecting background. Metal detectors and gold nugget detectors all rely upon some interesting properties concerning electromagnetic radiation.
That’s a fancy way of saying radio waves and how they interact with metallic objects. Oftentimes these wave interactions reveal some curious properties of induction or radio wave decay that can only be measured with precise electronics.
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It wasn’t until Gerhard Fisher in the 1920s began to perfect a specialized radio direction finding instrument for use in navigation when he discovered that these radio waves can be distorted by the presence of various metals.
After this, in the 1950’s Charles Garrett invented an instrument that made use of Beat Frequency Oscillation or BFO to stimulate metallic objects and locate them. One difficulty with this physical principle is that it’s highly susceptible to distortion from minerals and salts and low value trash metals that are in the soil around any metallic objects in fact even without objects false readings occur often.
The beauty of a BFO detector is its inexpensive cost to produce, the drawback being its susceptibility to distortion and false trash readings (BFO is a PITA, even if Walmart has them
The advent of discrimination through the use of pulse induction technology or PI in the 1970’s as it’s called in the detector field. These PI instruments work through the use of a large voltage spike and measurement of waveform phase for the decay of the spike over time. This measurement requires extremely precise electronics because of the small differences in the decay the metallic objects cause.
The power of PI technology is in its ability to discriminate even in the presence of large amounts of mineralization, trash metals or salts. Thus it can tune out a noisy background without losing track of small gold particles.
This trash vs. value discrimination is critical when it comes to being able to detect small particles or gold pickers on the surface or larger gold nuggets at depth and tell them from iron, pop tabs or tin foil easily.
The current age of metal detectors has advanced tremendously since the days of Alexander Graham Bell the compactness and accuracy and price have all put incredible power in the hands of the user.
At the same time the different uses for these detectors has grown immensely, from detecting gold, landmines, civil-works projects, in fact even some of the principles are at work in the medical field in the form of an MRI but that’s a whole different story.
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