Beginner's Guide To Metal Detectors
Some metal detectors are justifiably described as ‘all-rounders’ but there are many different types of metal detector.
Some detectorists are looking for gold and others are looking for coins or relics. Some will spend most of their time searching in fields, whereas others may spend their time looking on beaches.
So there are many considerations to take into account even before you think about the budget you have available.
This introduction to metal detectors has been written for beginners who are interested in learning more. It is useful to know a little bit about how metal detectors work before discussing the various types.
HOW DO METAL DETECTORS WORK?
Metal detectors have two metal wire coils in the head (the part that sweeps over the ground). The first coil is known as the transmitter coil, and the second coil is called the receiver coil.
When electricity flows through the transmitter coil, it creates a magnetic field around it.
Detectorists sweep the ground waiting for this magnetic field to cause a reaction in any nearby pieces of metal.
Any electromagnetic reaction is picked up by the receiver coil in the metal detector, and of course the receiver coil is connected to an audio speaker so the detectorist is alerted to any potential finds.
TYPES OF METAL DETECTOR
COIN, RELIC AND GENERAL METAL DETECTORS
These metal detectors operate on very low frequencies (VLF) and usually have a ‘discriminator’ mode which distinguishes between ferrous (containing iron) and non-ferrous metals.
A lot of hobbyists use the discriminator mode to filter out the second group, which is mostly low-value items.
Group 1 (High Conductivity) - Gold, silver, lead, copper, zinc, nickel
Group 2 (Low Conductivity) - Iron, tin, tin-foil, bottle tops etc
GOLD METAL DETECTORS
Gold metal detectors are more sophisticated than the general coin and relic models because in addition to detecting the electromagnetic reaction in any metals, it also measures inductance (how much current is in the metal) and conductivity (the flow of the current in the metal).
These values produce what is known as a ‘time constant’.
Different metal objects have different time constants, and gold metal detectors are calibrated to recognise objects with a time constant around the range most commonly found in gold.
This is a useful feature although not 100% accurate.
Metal detectors for kids work in exactly the same way, but they are shorter and lighter. Minelab, Joan Allen and Fisher all make metal detectors suitable for kids.
There are two main types of underwater metal detector:
Pulse Induction Metal Detectors
This type of detector transmits a series of electronic pulses into the ground.
They are not affected by wet sand or ground minerals, so they are great for the beach and they have a very good range, meaning they can detect things quite far beneath the surface.
They do, however, have limited discrimination capabilities, so you will inevitably have to dig up more low-value rubbish.
Very Low Frequency Metal Detectors
The VLF detectors are just waterproof versions of their land counterparts. They work in the same way and are able to discriminate between different types of metal with reasonable accuracy. These are useful in freshwater, but do not perform well in salt water.
UNDERWATER METAL DETECTING ACCESSORIES
You will also need
A sand trowel
A sand sifter
The bigger the coil, the deeper you can find things.
The Whites TM808 Detector can find large items up to 20 feet beneath the surface, although I’ve never heard of a hobbyist digging that far down.
These are the main brands selling to the UK and the US. This is not an exhaustive list. There are probably more than 20 brands in total.
Minelab are perhaps the biggest brand in metal detecting, not just hobbyists but in military, too. As one of the biggest, they have a huge research and development budget and this is evident in the large range of metal detectors on offer. They have a huge range to suit a variety of budgets and have dealers all over the world.
Garret is another worldwide brand with an impressive range of value-for-money metal detectors. As a family business, Garret prides themselves on customer service.
XP is a quality French brand, most famous for producing the XP Deus - a very popular, high-tech and high performance metal detector.
Fisher have been producing metal detectors (although not always the hobbyist kind) since 1931.
C.Scope have been producing metal detectors for over 40 years. All the design and manufacture is done in Great Britain, and they have 19 different products to suit everyone.