I can say without a doubt that this is the simplest metal detector I have ever seen. It is based on only one TDA0161 microcircuit. You will not need to program anything – just build and that’s it. Also, its huge difference is that it does not make any sounds during operation, unlike the metal detector on the NE555 microcircuit, which initially squeaks unpleasantly and you need to guess about the found metal by its tonality.

In this circuit, the buzzer only starts beeping when it detects metal. The TDA0161 microcircuit is a specialized industrial version for inductive sensors. And on it, metal detectors are mainly built for production, which give a signal when a metal approaches an induction sensor.

You can buy such a microcircuit at – TDA0161 aliexpress.com

It is not expensive and is quite affordable for everyone.

Here is a diagram of a simple metal detector

Metal detector characteristics

• Microcircuit supply voltage: from 3.5 to 15V
• Generator frequency: 8-10 kHz
• Current consumption: 8-12 mA in alarm mode. In the search state, approximately 1 mA.
• Working temperature: -55 to +100 degrees Celsius

The metal detector is not only very economical, but also very unpretentious.

A battery from an old cell phone works well for power.

The sensitivity will depend directly on the size of the search coil.

In the circuit, I use both light and sound alarms. You can choose one if you like. Buzzer with internal generator.

Thanks to such a simple scheme, you can make a pocket metal detector or a large metal detector, whichever is more necessary for you.

After assembly, the metal detector works immediately and does not need adjustments, with the exception of setting the response threshold with a variable resistor. Well this is standard procedure for a metal detector.