About myself
I am a Spanish self-taught programmer. I studied Industrial Electrical Engineering specialized in Robotics, Electronics and Automatic Control in the 80's, but I have never worked as an electrical engineer and developed my career focused on computer programming. I currently work as a software developer for payment solutions in the payment card industry, specialized in PCI and EMV compliance.
This competition is a great challenge for me. It has been almost 40 years since I studied electromagnetics and electronics and my knowledge of the subject is scarce. I have a lot to learn and really want to document everything I learn.
Me and magnetics components
I hardly know anything about magnetic components. For me they are something magical. When I was 12 I built a small FM transmitter, it was my first PCB and my first coil. At the time I did not understand how it works very well, but the transmitter worked and it was really fun to build it. Then my parents gave me an electronics learning kit for kids that I still have where there was a transformer and a variable inductor. I hope to recover those feelings with this challenge.
What do I want to experiment with?
My initial idea is to find a solution to discriminate coins with a microcontroller using a neural network fed by the changes in induction produced when bringing the coins close to a coil that will be producing an alternating magnetic field. I hope to find a method that allows working with components without very strict requirements.
The theory for the experiment. Inductive detection
When an alternating current flows through a coil, it generates an alternating magnetic field. If a conductive material, such as a coin, gets close to the coil, this magnetic field will induce circulating currents (eddy currents) on the surface of the coin. These eddy currents are a function of the distance, size and composition of the coin. These eddy currents generate their own magnetic field, which opposes the original field generated by the coil.
We can compare this mechanism with that of a transformer, where the coil is the primary core and the eddy current is the secondary core. The inductive coupling between both cores depends on the distance and the shape of the coin. Therefore, the resistance and inductance of the secondary core (eddy current) is shown as a distance dependent resistance and an inductive component on the primary side (coil).
Planning of the experiments
There are several experiments that I want to do.
- Experiment with impedance change by bringing different euro coins close to a coil that generates an alternating magnetic field. Changes produced by coin material, distance and angular position.
- How to generate the alternating magnetic field with a coil. Experiment with LC oscillators. Test Colpitt Oscillators.
- Inductive sensing:
- Inductive sensing with an external 3-axis magnetometer.
- Inductive sensing with Analog to Digital Converters, sensing changes in resistance and inductance.
- Inductive sensing with another receiver coil.
- Train a machine learning model to sort euro coins.
- Putting all together. The smart coin sorter.
The kit
This is the kit that I have received. Component 8 is missing, inductor, 100 uH. No problem, there is a lot to learn from the other 14 components.
The first thing that surprised me is the annotations on the different components, I am not able to determine at a glance what each component is. One more task on the list of things to learn.
| {gallery} Bourns Magnetic Components Kit |
|---|
Bourns Line Filter, 51uH Top |
Bourns Line Filter, 51uH Bottom |
Bourns RF Choke, Radial Lead, 3.3uH |
Bourns RF Choke, Radial Lead, 3.3uH |
Bourns RF Choke 47uH |
Bourns HIgh Current Choke 47uH |
Bourns HIgh Current Choke 47uH |
Bourns 400 Volt Radial Inductor |
Bourns 400 Volt Radial Inductor |
Bourns Inductor, Radial Leaded, 1mH |
Bourns Inductor, Radial Leaded, 1mH |
Bourns RF Choke, 1.8 mH |
Bourns Common Mode Choke, 12.5 uH |
Bourns Common Mode Choke, 12.5 uH |
Bourns Common Mode Choke, 9uH |
Bourns Common Mode Choke, 9uH |
Bourns Common Mode Choke, 7.5uH |
Bourns Common Mode Choke, 7.5uH |
Bourns Common Mode Inductor, 470uH |
Bourns Common Mode Inductor, 470uH |
Bourns Pulse Transformer, 300uH |
Bourns Pulse Transformer, 250uH |
Bourns Pulse Transformer, 300uH |
Bourns Pulse Transformer, 300uH |
Bourns Choke, 100mH |
 |
My lab equipment
I do not have an electronics laboratory at home but I have some equipment with which I pretend to be able to obtain the necessary data for the experiments:
USB Oscilloscope Digilent Analog Discovery 2USB Oscilloscope Digilent Analog Discovery 2
The Analog Discovery 2 equipped with 13 test and measurement instruments in one device. It provides Oscilloscope, Waveform Generator, Logic Analyzer, Protocol Analyzer, Spectrum Analyzer, Power Supplies, and more.
Digital Multimeter: Multicomp Pro MP 730026 Digital MultimeterMulticomp Pro MP 730026 Digital Multimeter
The Multicomp Pro MP7300263 5/6 bit resolution handheld digital multimeter featuring a data logger, thermometer and non-contact voltage detector.
DC Power Supply: Hanmatek HM305P
Output Voltage: 0-30V four digit display, Output Current: 0-5A four digit display
The microcontroller
I will use an Arduino nano 33 BLEArduino nano 33 BLE
The Arduino Nano BLE has:
- a 9 axis Inertial Measurement Unit (IMU), an LSM9DS1 iNEMO inertial module: 3D accelerometer, 3D gyroscope, 3D magnetometer
- and analog inputs 8 (ADC 12 bit 200 ksamples)
Thanks
Thanks to Bourns for sponsoring this challenge and to element14 for giving me this opportunity and organizing this event.