€80
pledged of €3,150pledged of €3,150 goal
7
backers
Funding Unsuccessful
The project's funding goal was not reached on Sat, March 10 2018 8:41 PM UTC +00:00
Marco MalinverniBy Marco Malinverni
First created
Marco MalinverniBy Marco Malinverni
First created
€80
pledged of €3,150pledged of €3,150 goal
7
backers
Funding Unsuccessful
The project's funding goal was not reached on Sat, March 10 2018 8:41 PM UTC +00:00

About

A little board to implement professional metal detector functionality in your electronics projects.

Metal detecting is a hobby that few people know, but that is practiced all over the world. There are even strict laws that regulate it, which allow us to understand the importance of this passion. Anyone can practice it, but one reason that few people approach this hobby is the cost of the necessary equipment. What I propose, is a small board that can be connected to your favorite development platform, via the i²c bus, able to transform it into a metal detector.

The Idea

AD5933 Impedance Converter
AD5933 Impedance Converter

The core of the system is AD5933, a high precision impedance converter which contains a Sine Wave DDS (Direct Digital Synthesis) Generator from 1 kHz to 100 kHz, and a DFT (Discrete Fourier Transform) Processor to create the Real and Imaginary components of the complex impedance. In our case, the metal detector coil impedance.

More at http://www.analog.com/en/products/rf-microwave/direct-digital-synthesis/ad5933.html#product-overview

The Project

No prototype has been created yet, only schematics and files necessary for the production of the board have been created using kicad (open source EDA software).
You can see some screenshoots below.

Kicad I²C Metal Detector Project
Kicad I²C Metal Detector Project

How does it work?

This metal detector is just an add-on, so it can't work in a stand-alone mode. It must be controlled by an external unit (Arduino, RaspberryPI etc) that has the task of managing the functions of this board.

Every metal detector requires a calibration to work, done near the ground where we want to search for metallic objects. During calibration, the AD5933 will create, for each frequency, the Real and Imaginary values in the corresponding registers contained within it. The external unit will read and then store these values via the I²C bus.

It is now possible to start  searching. Whenever the coil is in correspondence with a metallic object, the registers inside the AD5933 will change values. The task of the external unit is to compare the values of the registers with the previously stored values. If the difference between these values exceeds a preset threshold, the central unit will activate an indicator, sound a buzzer, or display it on a bar graph.

Depending on how much memory is available on the external unit, more than one pair of calibration values can be stored. It will, therefore, be possible to cyclically switch different search frequencies in a fraction of a second.

What can I do with this add-on?

You can, first of all, realize the most common of metal detectors, to locate metal buried underground, well known by anyone, as you can see in the renders below.

DIY Metal Detector
DIY Metal Detector
DIY Metal Detector Display
DIY Metal Detector Display

Or why not, if you have good robotics knowledge, you can also make a super cool robotic metal detector.

Robotic Metal Detector
Robotic Metal Detector

Risks and challenges

This project is based on a new concept of operation, compared to that of metal detectors that are on the market. What I hope to verify is a variation of the imaginary component produced by the AD5933 in the presence of a metallic object, but I can not do it without a working prototype. The cost of the material to make a single card is not high, but it may be necessary to make several changes to the schematic, to optimize it, which would correspond to an economic expenditure. Therefore, the objective of this first fundraising is only to verify the possibility of using an AD5933 as a metal detector. Otherwise, the project will be abandoned. I believe that sincerity and clarity are the basis of every relationship. I place a lot of trust in what I hope to achieve.
Thanks to everyone who will help me

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Funding period

- (30 days)