When deciding on a hobby metal detector you will likely run into three technologies - Beat Frequency Oscillation (BFO), Very Low Frequency (VLF), and Pulse Induction (PI). Each technology offers the user positives and negatives and may work better or worse depending on a number of factors. You will want to choose based on your hunting style, skill level and/or detecting requirements. A question often asked to Kellyco is “how do you make that decision?” Read on to get a basic rundown of how each technology works and their most common use.



Beat Frequency Oscillation (BFO)

Hobby metal detectors in the BFO category are typically basic, user-friendly (‘turn on and go’) metal detection technology. There are two rings of copper coiled around iron or steel. A current of energy passes through them and transmitted into the ground. When the signal is broken or disturbed by metal, the detector creates an audible change in sound audibly alerting the user to a potential target. Because of how basic these detectors are, they are a great choice for novice detectorists who want to hunt in clean areas. Detectorists who are looking for an easy to use budget-friendly option may find them acceptable as well. The main thing to remember is that they will pick up on any metal in the ground without being able to tell the difference between a “good” or “bad” target. We currently do not carry any BFO metal detectors.


Very Low Frequency (VLF)

This type of metal detector uses two coils, one sends and the other receives, to pick up on targets in the ground. The sender coil creates a magnetic field that reacts to metal objects. When a target is found, a current is formed, the receiver coil takes the signal and amplifies it to be heard through a speaker or headphones. Many detectors can even translate the signal into a number based on how strong the magnetic current is.


Because of its ability to give information back on targets, there are lots of metal detectors that use VLF technology. The control box is where the magic happens with this type of detector. It interprets the signal and turns it into easy to understand visual and audio cues. Depending on how much work goes into the interface and controls, you can ignore targets you don’t want to dig, see about how deep a target is, change the sensitivity, and much more.  


Most detectors are set up for specific types of hunting. For example, the settings on gold detectors like the Nokta Makro AU Gold Finder take into account the hot rocks and ground that are encountered in a gold field. Some of the newer detectors, like the Garrett AT Max or Minelab Equinox Series, are set up to be used in multiple soil types with preset programs that change settings fairly easily.


Pulse Induction (PI)

While the previous types of metal detector technologies used two coils working together, Pulse Induction (PI) can use one or more coils in a much different way. The coil sends out bursts of electronic currents that bounce back when it hits a metal object. The best way to think about PI is that it’s like a bat’s echolocation. There is no way to tell the difference between targets - just that there is one.


The greatest advantage to these types of detectors is that they search much deeper than the BFO or VLF. If you plan on searching for very deep targets a detector such as the Garrett Deepseeker will give you the best results. Many beach detectors, such as the White's Surfmaster PI Dual Field use PI as well. It is very stable and reliable at finding targets even in the salt found in beach water and sand.


There are many metal detectors on the market for a wide range of needs and experience levels. It’s easy to get overwhelmed or choose one that does more than you will ever need it to. Finding the detector that fits your needs boils down to choosing the features you need. This is why we have a team of metal detecting experts who can help match you up to the right detector. Give us a call and we would be more than happy to assist you!