Gold detectors, which are specialized metal detectors, work by generating an electromagnetic field and analyzing how that field interacts with metallic objects in the ground. Different types of gold detectors use slightly different technologies, but the fundamental principle remains the same.
Here's a breakdown:
1. Creating an Electromagnetic Field:
- The Core Component: A gold detector contains a coil of wire called the search coil.
- Generating the Field: The detector sends an electrical current through this coil, creating an electromagnetic field that extends into the ground.
2. Interaction with Metallic Objects (specifically Gold):
- Target Response: When the electromagnetic field encounters a metallic object (like gold), it induces a small electrical current within the object.
- Secondary Electromagnetic Field: This induced current generates its own, weaker electromagnetic field around the metallic object.
3. Detection and Analysis:
- Receiving the Signal: The detector's circuitry monitors the original electromagnetic field and looks for changes or disruptions caused by the secondary field from the metallic object.
- Signal Processing: Sophisticated electronics analyze these changes in the electromagnetic field. Different metal detectors use various techniques for analysis. For example:
- Very Low Frequency (VLF) Detectors: These detectors transmit a continuous signal at a low frequency and analyze the phase and amplitude of the returning signal. They are good at discriminating between different types of metal but can be affected by ground mineralization.
- Pulse Induction (PI) Detectors: PI detectors send short, powerful pulses of electricity through the coil. When a metallic object is detected, the pulse creates eddy currents. The decay time of these eddy currents is then measured. PI detectors are less sensitive to ground mineralization than VLF detectors, making them better suited for highly mineralized soils.
4. Alerting the User:
- Audio and/or Visual Indicators: Based on the analysis of the returning signal, the gold detector alerts the user, typically through an audible tone, a visual display, or both. The nature of the signal (tone pitch, display readings) can provide clues about the type and size of the detected metal.
Key Differences in Gold Detector Technologies:
| Feature | Very Low Frequency (VLF) | Pulse Induction (PI) |
|---|---|---|
| Signal Type | Continuous wave | Pulsed |
| Sensitivity | Good to small gold | Excellent to Larger gold, and good at depth |
| Ground Minerals | Affected | Less Affected |
| Discrimination | Good | Limited |
| Best For | Prospecting in less mineralized areas, relic hunting | Highly mineralized ground, beach hunting |
In summary, a gold detector works by creating an electromagnetic field, sensing disruptions to that field caused by metallic objects, and then alerting the user to the presence of potential gold or other valuable metals. Different technologies like VLF and PI offer different advantages depending on the specific environment and desired targets.
