False signals

Metal Detector Gives False Signals.

The metal detector sometimes gives false signals. This is not an entirely unusual phenomenon; you get a false signal for no apparent reason. There can be several reasons why it happens, but I will describe the most common ones.

search coil - Metal Detector False Signals

Metal Detector Troubleshooting – on the beach

In wet sand on saltwater beaches, you can get numerous false signals. Using the detector on dry sand is usually fine, but it gets worse if the sand is wet.

There can be several reasons for such signals, but usually, it is due to the electrolytic reaction of the salt present in the sand, which causes negatively charged minerals to become “positive”. This causes the search coil to come out of its basic setting, which forces the detector circuits to generate a false signal. Read: Metal detecting on the beach

Cartoon Beach

Coal and Ceramics Can Give False Signals 💎

The fact that the Metal Detector gives false signals can, for example, be due to the electrical properties of an object. Charcoal, ceramics, and some earthenware can provide false signals. Then, their electrical properties are rather “capacitive” than “conductive”.

When the metal detector’s magnetic field reaches such an object, the object absorbs a small amount of electricity from the magnetic field. This, in turn, generates a secondary magnetic field, which produces changes in the coil and gives a signal. It is common to find excess carbon in the ground, which can provide misleading signals.

Black sand and Gold

Iron oxides like Magnetite and Hematite can also cause false signals. Magnetite is the main component of “black sand” and is common in mineralized soil, for example, where you look for Gold

Lowering the sensitivity and readjusting the “Ground Balance” can help eliminate error signals.

Gold and black sand i a pan - Metal Detector Gives False Signals

When the Detector Buzzes and Hums

Sometimes, the detector may make a humming sound. This is usually due to the presence of an electrical interference source nearby. It can be high-voltage lines in the air or underground. Or electric fences nearby. It could also be that you yourself have something that disturbs the detector—for example, a mobile phone.

If you believe something in your surroundings is disturbing, you can lower the detector’s sensitivity; it usually works well. A mobile phone can be set to “Flight mode“. If you have two metal detectors running simultaneously, they can interfere with each other if they get too close.

False signals when Swinging 🎶

Sometimes, you can get false signals at the far end of your swing. It’s probably because you lift the coil at the end of the swing. The search coil will then perceive a rapid change in the magnetic field, causing a false signal. 

Try to get as smooth a swing as possible, both in speed and height. You can get a similar error signal if you hit something in the swing. Then, you can also get a false signal.

Metal Detector Gives False Signals Swing technic

False Detector Signals from Cables and Electronics 💥

The wiring between the search coil and the electronics box can cause false signals if the cables are too loose or damaged. However, I have never encountered this particular problem myself.

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