Felezjoo with the ability to discriminate.

[sabios]

1. Timing of the current BEFORE/NEXT windows of the FelezJoo
2. Recommended R/C values for MID and LATE windows in a 150µs/380µH PI circuit.

If anyone wants to participate in this project.

The idea is to make the FelezJoo capable of reliably discriminating between different metals. I'm not doing it myself because I lack the necessary tools, and this requires a more complete oscilloscope, which I don't have.

And of course, I also need to change the ATmega2560, as it's necessary for the switching.

The idea is to measure the difference between different metals.
I already have a schematic for this, but I need the timings.
To ensure everything works correctly when programming, I already have a preliminary version, but only for ferrous metals. The other metals are easier to distinguish with the switching, but my goal is for it to be able to distinguish between different metals.

[pito]

If you will use esp32 wroom i can participate

a more complete oscilloscope = PC visual analiser2011 , free software

[sabios]

Electronic Components for Arduino Mega2560 with USB Cable - PMB-01

That's the one I'm going to use, but only for the prototype, since once I finish I plan to redesign the board to implement the new ATmega2560 chip.

As mentioned, what I need is the R/C, but it has to be for this Felezjoo, since each detector has different curvatures with different metals, and therefore the timings are different.

[haylaz0036]

Dear Sabios, your ideas are truly excellent. Your concept of a device capable of distinguishing all types of metals is great. The 2560 processor might be suitable, but I strongly recommend using sampling. Many engineers have used the LF398 in professional machines and achieved excellent results. Also, please change the device's name; it's called Felejoo everywhere. Please use a different name.

[sabios]

You're right about that, and in fact, I already have the new software, which is a version I call PulseMaster. It uses a 20x4 LCD screen. Currently, I only have it on the Felezjoo, but on some custom-made boards, I've already replaced it with DW.

As I said, it's a change I want to make, and my idea is to add more sampling windows so the detector can differentiate between metals.

1. Make a few changes and add the ATmega2560 chip, since it's capable of doing this. I already have software that can control the Arduino Mega2560 by simply adding a few wires, but it's only for the prototype. To make it more complete, I would integrate the chip directly onto the board.

2. With that, I would be able to add more sampling to differentiate metals. The easiest way is to just add two more samples for gold and silver, and copper and bronze. That would be the simplest way.

3. Add more samples for almost all metals.

Finally, for this I use the R/C but it has to be for the Felezjoo plate since this is the base of everything because now that I have assembled it I can say that it is very stable and has good depth.

[pustareka]

It is almost impossible to discriminate coloured/black targets with single Tx pulse excitation. Strobe time shift delay is of little help. Answer is splitting the positive or multiple spectra Tx pulse excitation with advanced additive sampling, averaging and complex time domain filtering. The logic is simple - one man know a lot but 1 0000 man coordinated and connected know 1000x times more than a single male.

Suggest to analise and study coils echo-coefficients calculator or FIR echos of Tracker-PI 2 as a starting base and improve the code for you needs. Source could be easy compiled to any Atmel microcontroller with IAR Embedded Workbench for AVR V7.30.4.

[pito]

this is a very popular picture of discrimination, but never sowed it in real life = on oscilloscope

[Detectorist#1]

Hi pito,
My observations with DD coil and very precise IB, shows that have something right in this picture. When I set the delay to 12us, the detector totally not react to ferrite bar. At 10us delay the detector starts to react on very close ferrite and for delay of 5us the detector haves very strong reaction to ferrite bar. Also, at under 12us delay, the polarity of the signal for non-ferrite targets is opposite. In short - this popular picture is true! These measurements was made for short sampling pulses (4us) and after amplifying (x1000) of the signal after the integrator. It is not possible to observe directly the signal on the RX coil - the level of the signal is in microvolt range.

[pito]

will be nice to see video of that = changes on oscilloscope

[sabios]

This is the first test to demonstrate some of the discrimination capabilities of this detector.

By the way, this is a PI metal detector with the ability to discriminate metals by conductivity. It can be used to search only for more conductive metals like copper, gold, and silver. It's still in the testing phase, but for now, it's able to reject metals like aluminum, iron profiles, nails, rods, pewter, and other metals, which are marked as FERRO. Copper, gold, and silver are marked as NON-FERRO on the screen, making identification much easier.

It's still in the testing phase; for now, this is the best I've been able to get out of this detector. As I said, it's an improvement I've achieved, but it's still in the testing phase since I need to find the limits of the conductivity discrimination. Finally, it's capable of being used as an all-metal detector like any PI metal detector, or using conductivity discrimination, but that reduces its depth a bit. For now, I've only tested it with that coil; I still need to see if it works the same with the square one.

https://www.youtube.com/watch?v=Y6s9TrW458I&t=14s

[haylaz0036]

This is the first test to demonstrate some of the discrimination capabilities of this detector.

By the way, this is a PI metal detector with the ability to discriminate metals by conductivity. It can be used to search only for more conductive metals like copper, gold, and silver. It's still in the testing phase, but for now, it's able to reject metals like aluminum, iron profiles, nails, rods, pewter, and other metals, which are marked as FERRO. Copper, gold, and silver are marked as NON-FERRO on the screen, making identification much easier.

It's still in the testing phase; for now, this is the best I've been able to get out of this detector. As I said, it's an improvement I've achieved, but it's still in the testing phase since I need to find the limits of the conductivity discrimination. Finally, it's capable of being used as an all-metal detector like any PI metal detector, or using conductivity discrimination, but that reduces its depth a bit. For now, I've only tested it with that coil; I still need to see if it works the same with the square one.

https://www.youtube.com/watch?v=Y6s9TrW458I&t=14s

I've been following you, the discrimination works really well.

[pito]

FERRO. Copper, gold, and silver are marked as NON-FERRO on the screen, making identification much easier. = it is not easier using LCD, easier is different sound

[sabios]

I have bad news. After using it for a while, it seems the LF357 was indeed damaged when the 7805 burned out. Now the debugging values are far below the specified values, and therefore the discrimination isn't working properly. For the LF357 to function correctly, the values need to be accurate, meaning it has to be genuine. So, for now, until I can get the right replacements, I'm waiting.

I'm thinking of replacing them with something easier to find, but it's complicated; I need to do more testing.

[pito]

https://www.google.com/search?q=LF35...hrome&ie=UTF-8
I will use modern 5V MCP6022

[sabios]

By the way, this is the motherboard I'm using. You can see it has small changes, but it's there.