Back in the days of the Gold Rush, prospectors had to rely on panning and a number of rudimentary methods to locate gold and other precious metals. Even if the techniques back then were less complex than today, they still served the same purpose of finding things that were hidden beneath the surface. It was the thrill of uncovering hidden treasures that fueled their adventurous spirit and kept them going.
This same sense of adventure still lives on in modern-day treasure hunters. Now, instead of using pans to sift through dirt and mud, they use state-of-the-art metal detectors to precisely locate metals and other objects buried beneath the surface. While it’s not necessarily one of the most common hobbies to try, metal detecting certainly brings a certain level of excitement and fun that is difficult to find elsewhere.
What Types of Metal Detectors Are There?
The type of metal detector you buy will largely depend on the nature of your endeavours and expected outcomes. Currently, there are three main types available, depending on their technology:
Very Low Frequency (VLF) Detectors
As the name implies, these devices use very low frequencies which allows them to detect both ferrous and non-ferrous metals. They rely on an electromagnetic field to detect objects up to 30 cm deep and are ideal for searching the ground or shallow beaches.
The way VLF detectors work is by sending out low-frequency signals which, when they encounter a metal object, cause an interruption in the signal field. This interruption is then returned to the detector, allowing it to identify the type of metal and its location.
Pulse Induction (PI) Detectors
Unlike VLF detectors, PI detectors use a single transmission of high-power current pulses. This signature is then read by the detector which determines if there are any metal objects buried beneath the surface. Since pulse induction technology only requires one transmission, it can detect objects up to 80 cm deep across mineralised and salty grounds.
As such, PI detectors are the go-to choice for beach hunters and treasure seekers who want to locate objects buried much deeper than most VLF detectors can reach. When the pulse current is received by the detector, it’s then converted into a digital audio signal which can be heard by the user.
Beat Frequency Oscillation (BFO) Detectors
Also known as induction balance detectors, these devices use two signals that are combined to form a beat frequency. The detector then reads the difference between these two frequencies and uses it to determine whether or not there is metal beneath the surface.
These devices are usually the most basic and cost-effective devices in comparison to VLF and PI detectors since they don’t require any complex electronics. The main disadvantage is that BFO detectors adopt a simplistic approach that restricts their detectability to non-ferrous metals only.
Main Components of Metal Detectors
Regardless of which type you choose, all metal detectors will have the same five main components that make up their basic structure. Their design may vary slightly from model to model, but the overall components are the same.
This is the main unit of the detector and houses all of its essential components. It is typically fitted with a display screen that shows the current settings, target type, depth of the object, and other essential information.
Depending on the exact model, some control boxes may also have additional features such as audio settings or an adjustable shaft. The former allows users to adjust the audio output for more accurate results, while the latter can be adjusted to fit different body sizes.
Next up is the loop-shaped antenna that emits electromagnetic fields and receives signals when it comes in contact with metal objects. It generally has a round shape and is either made from a single wire or multiple wires that are wound together. The size of the search coil can vary between models, but the general consensus is that the larger it is, the better detection range it will have.
Similar to a fishing rod, the shaft is what connects the search coil to the control box and is typically made from lightweight materials such as aluminium, carbon fibre, or fibreglass. The wavering motion of the detector is controlled by the length and flexibility of the shaft, with smaller, more rigid models providing better control over the device.
The stabilising bar or harness is what helps to minimise the motion of the device when searching for metal objects. It attaches to the shaft and helps to keep the device steady, which in turn provides more accurate readings.
For users who expect to be using the device for extended periods of time, it’s highly recommended to opt for models that come with a comfortable and adjustable harness. Others may opt for a stabilising bar, which is mounted directly onto the shaft.
Finally, the power supply is what provides the necessary energy for all of the device’s components to work properly. Most models run on regular AA batteries, while some may be powered by rechargeable ones. The former could be a good option for casual users, while the latter is ideal for more intensive use.
Some options even come with an external power supply, which can be used to run the device in areas where batteries are not allowed or practical. When the separate power source is connected to the detector, users are able to run it for an extended period of time without running out of juice.