Metal detecting, whether coin collecting or treasure hunting, is a thrilling and addicting hobby. The key component to "dirt fishing" and "coin-shooting" is the metal detector, sold in three different varieties--beat-frequency oscillation, very-low frequency and pulse induction. Your budget, the terrain and the precious treasure you are after will help you decide which metal detector is the right choice for you.
Very-low frequency (VLF) is the most commonly purchased and most widely used type of metal detector, according to RadioShack.com. VLF utilises two coils combined into one that work together to send and receive signals created by a distorted magnetic field originating from the location of a metal object. The signal sent to the control box alerts the user with an audio tone through a speaker.
Beginners just learning to dirt fish will want to choose a beat-frequency oscillation (BFO) metal detector; this type is the least expensive of the three types. Similar to VLF, a BFO detector uses two coils, one within the search head and one in the control box. However, the coils are not combined together. Steady pulses emanate from an oscillator connected to each coil, creating frequencies that vary slightly between each coil, resulting in radio waves. Metal objects are detected by interference of the radio waves, sending an audio tone directly to the speaker.
Treasure hunters in serious search of precious metals, whether in the ground or under the sea, typically use a pulse induction (PI) metal detector, which is more sensitive than VLF and BFO. PI detectors can utilise one to three coils, which transmit a pulse into the ground to detect metal objects. Once detected, the object creates a pulse that is reflected back into the sampling circuit, which sends an alert to the control box. While PI detectors are more sensitive, they are less able to discriminate between a valuable item and a discarded bottle cap.