Moodz' Awesome Gold Pulse Induction Version 3 - MAGPI V3 Project

[moodz]

Not sure what you mean Orbit ... you mean by witness that Ivica is very observant. He will need to be very observant to reverse engineer my video

Meanwhile I applied amplification and we have the input to the ADC ready for processing ... on track so far. Here is a video.

https://youtu.be/QYfQF4IDY0w?si=cIvg5jXp22FaFW4-

[ivconic]

You gave the schematic and the whole project, there is nothing for reverse engineering.
Anyway, in recent years I have been very poorly motivated to do such things.
Very bad times have come for the detector business.
And if I had the source code and detailed schematic and pcb design for say Deus 2 or ML GPX5000 or any other ...
I wouldn't know what to do with it? Who to sell it to?
Even the Chinese are not motivated to reproduce it any more. Because that business is in sharp decline.
There is a better chance of finding something valuable with the detector than making money selling the detectors.
And there is an even greater chance of winning the lottery or taking more serious money in the casino.
I'm still here on the forum just for the love of the hobby. Otherwise, everything else has lost its importance.
When I started doing this... there were ~ 10 detectors in the state. Today there are 10 detectors per capita!
Will we turn the situation around if we invent something new?
No, we won't. In the total world population, we are at the level of statistical error!
...
Good chicks look at us as a "weird little group of fun boring people" !!!

[lxs17757414132]

You gave the schematic and the whole project, there is nothing for reverse engineering.
Anyway, in recent years I have been very poorly motivated to do such things.
Very bad times have come for the detector business.
And if I had the source code and detailed schematic and pcb design for say Deus 2 or ML GPX5000 or any other ...
I wouldn't know what to do with it? Who to sell it to?
Even the Chinese are not motivated to reproduce it any more. Because that business is in sharp decline.
There is a better chance of finding something valuable with the detector than making money selling the detectors.
And there is an even greater chance of winning the lottery or taking more serious money in the casino.
I'm still here on the forum just for the love of the hobby. Otherwise, everything else has lost its importance.
When I started doing this... there were ~ 10 detectors in the state. Today there are 10 detectors per capita!
Will we turn the situation around if we invent something new?
No, we won't. In the total world population, we are at the level of statistical error!
...
Good chicks look at us as a "weird little group of fun boring people" !!!

Hi, I'm Chinese. The PI market is very chaotic now, and there are a lot of people selling machines. Recently, a large number of people are starting to clone other people's boards

[ivconic]

Hi, I'm Chinese. The PI market is very chaotic now, and there are a lot of people selling machines. Recently, a large number of people are starting to clone other people's boards

No problem, that's true. But is there any money in such attempts?
Not any more.
Too many detectors already.

[Orbit]

The worst thing is to do experiments for two months in order to do something smart and get tired of sitting on a chair. .And then someone teases you, but actually talks nonsense out of ignorance and envy.

[Detectorist#1]

Hi Moods!
It is very strange for me how you have the claim for sampling noise reduction with using of LM6171 as front end. This IC have 130nV and 8pA noise at 2Hz.
Where is "hidden the dog"?

[KingJL]

Hi Moods!
It is very strange for me how you have the claim for sampling noise reduction with using of LM6171 as front end. This IC have 130nV and 8pA noise at 2Hz.
Where is "hidden the dog"?

Sometimes the focus on a single tree hides the benefits of the forest!!

[Orbit]

Sometimes the focus on a single tree hides the benefits of the forest!!

[moodz]

Sometimes the focus on a single tree hides the benefits of the forest!!

Could not have put it more succinctly than that

[moodz]

Hi Moods!
It is very strange for me how you have the claim for sampling noise reduction with using of LM6171 as front end. This IC have 130nV and 8pA noise at 2Hz.
Where is "hidden the dog"?

To answer your question ... the Magpi 3 is a "demonstrator" platform not a "uber detector". I spent all of 5 minutes selecting that opamp. The reason it was chosen ( say rather than a NE5534 and I am not saying the NE5534 is choice either) is that it can take rail to rail overload voltages at the input whereas the NE5534 has the equivalent of diodes across the inputs so any overload voltages above 0.6 volts cause current to flow in the opamp inputs. This is not good as it a causes errors in the current damping that the V3 uses.
Feel free to choose your own opamp ... V3 is for experimenters.

For instance the noise cancelling loop still does a great job ( even with the 6171 ).

And importantly PI ferrous / non ferrous discrimination is there in plain site ( bad luck .. patent guys ) ... it just was not implemented in V3 ... but can be with simple software change.

[moodz]

THIS IS HOW YOU DO DISCRIM ON THE MAGPI >>>>

I have got to do some other stuff so I will describe the MAGPI discrimination method.

If you have been reading the thread the MAGPI is basically a single channel machine and uses an X sample ( reactive ) to control the damping via a feedback loop and an R sample ( real ) for the actual target detection.

In normal MAGPI operation you dont really see metal discrim because the damping feedback loop clamps the X sample to a relatively fixed DC level that controls the damping mosfet.
HOWEVER if you first "open" the control loop temporarily and thus keeping the damping mosfet at a fixed bias for a short time ( maintained by gate capacitor ) the X sample will now provide target discrim information. So if the R sample timing is now moved to X sample timing you get discrim info on the target. ( ie Ferrous / non Ferrous ) QED as they say.
You could arrange for this to happen by a push button so that you can ID a target or it could happen all the time.

See post #293 for image of result.

Pic below ...

[Detectorist#1]

Hi Moodz,

Thank you for these additional explanations! I know, the real things are more complex than seems at first look.
The idea for use current load for fast damping in not bad, but using of fast coils allow to make first sample after 2.5us TX switch-off and this is more fast than the time in your time diagrams.
The path for improving PI MD become more and more complex, but this will not stops our common efforts!
Success!

[moodz]

Glad you like it ...
Fast coils are fast because the capacitance is low .. however if you utilise the energy in the coil ( 1/2 LI squared ) the capacitance term is not there and the time constant of a shorted cap approaches zero... so capacitance is less consequential.

So regardless of how "fast" the coil is my latest circuit can damp a typical PI coil in around 500 nanoseconds ... much faster than anything else I am aware of

[Detectorist#1]

Hi Moodz,
Really very impressive - 500ns! In my practice (not very big), every attempt to use delays under 2.5us haves bad results - the screen of the coil stops to works as screen and the connecting cable starts to be more sensitive
to near hands than the coil. It seems for me, these 2.5us are "magic" border! Do you have some explanation for this effect? Or I not understand what really happens?
Thank you in advance!

[Teleno]

Hi Moods!
It is very strange for me how you have the claim for sampling noise reduction with using of LM6171 as front end. This IC have 130nV and 8pA noise at 2Hz.
Where is "hidden the dog"?

The target decay is exponential so the additional op-amp noise is compensateď for by a larger signal of earler sampling.