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How to Use a BFO Metal Detector

A BFO metal detector, or a beat frequency oscillator, is the most basic and the oldest type of metal detector. Many BFO detectors are constructed by do-it-yourself enthusiasts out of basic parts as either a hobby or for practical use. The basic operation of a BFO detector uses two radio frequency oscillators both tuned near the same frequency. When a piece of metal disturbs the search coil's magnetic field, the search oscillator frequency shifts slightly and the detector will produce an audio frequency signal. Learning with a BFO detector is the best way to learn basic metal detecting skills.

Instructions

- 1
  Adjust the search oscillator by either unscrewing it slightly or turning the knob if applicable to the lowest frequency on your dial. An ideal frequency is between 40 to 100 Hz. You will hear the lowest amount of static at the lowest frequency.
- 2
  Adjust the reference oscillator knob or screw to the same frequency as the search oscillator.
- 3
  Hold the metal detector out and walk slowly. Keep the metal detector coil about five inches from the ground. Pass the detector back and forth as you walk.
- 4
  Listen for an audible difference or shift in the static noise coming from the detector. This indicates that you've passed over a metal object. Most BFO detectors can only detect metallic objects at a depth between six and 10 inches.

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