Measuring PHASE SHIFT IN PI

[Tinkerer]

Gday Tinkerer,

I have been trying to simulate your Pivot & the sine wave, if this is it i may have an explanation for it & can give the spice model for it, have a look at the pictures & see if it resembles what you find?

Opposite Polarity of signal inverts the pivot.

Thanks B^C,

there is a good chance that you are right. I am going to post some scope pictures of it as soon as I get it ready, showing small and large targets of different metals and shapes.

Tinkerer

[Tinkerer]

This is very interesting thread but we need to include schematic with coils and where measurements we are talking about.

Cheers,

-SB

We will get there. It looks as if a lot of information and knowledge is coming together on the subject.
I am grateful for your feedback.

Tinkerer

[Tinkerer]

Hi,
I was serious... I heard of elephants that fart so much that a medium sized car can run for 40Km with 24hours production of "methane" there...

What a global warming! I swear that's true!

About the discriminating PI... uhm... seems like the holy grail... or something... I'm still waiting for the pulsedevil but I think will not see soon... just an impression.

Kind regards,
Max

Hi Max,

I hope I did not offend you. Just trying to be funny. It is not easy. so much gets lost in translation specially with jokes.

The holy grail, the impossible dream, reach for the stars. These things do have some appeal.
I think a discriminating PI fits into this category.

All the best

Tinkerer

[Max]

This is very interesting thread but we need to include schematic with coils and where measurements we are talking about.

Cheers,

-SB

Hi,
yes... that's common problem when talking about disc-PI things... people start to think they discovered some holy stuff then start claiming they have patented it... and that the production is running and the wonderful 1st fully discriminating PI will hit the market next month.

Then nothing. Nobody calls... and you don't know if it's cause of some hurricane or vampire why the hell the design is lost forever...

What to say... already seen on the screens!

Just remakes...

But where is a workable circuit for that ???

Just I say there are things that could measure (sometimes) the conductivity of target if a specific size is matched... but cause you don't know which is the actual size of the buried target (do you ?) before digging it... they are mostly unuseful to me , at least!

Kind regards,
Max

[Max]

Hi Max,

OK we will make a special environmentally friendly model for you.
We take this picture of the elephant, roll it up and stick it into coil.
Then we zap it with 66A current to generate a 666 Gauss B field intensity.
This should beat enough C_R_A_P out of the elephant to generate rainbow colored eddy currents.

Tinkerer

Hi,
I was serious... I heard of elephants that fart so much that a medium sized car can run for 40Km with 24hours production of "methane" there...

What a global warming! I swear that's true!

About the discriminating PI... uhm... seems like the holy grail... or something... I'm still waiting for the pulsedevil but I think will not see soon... just an impression.

Kind regards,
Max

[simonbaker]

This is very interesting thread but we need to include schematic with coils and where measurements we are talking about.

Cheers,

-SB

[aft_72005]

What kind of ground conditions did you use it in? Highly mineralized, or just mild ground?

Cheers

It had more false signal when use in minerals ground than mild ground.
Best regards.

[B^C]

Gday Tinkerer,

I have been trying to simulate your Pivot & the sine wave, if this is it i may have an explanation for it & can give the spice model for it, have a look at the pictures & see if it resembles what you find?

Opposite Polarity of signal inverts the pivot.

[Mechanic]

Hi Qiaozhi
I design and built discrimination pi detector approximately seven years ago.
It had capability discriminate between Ferro and nonferrous metals.
If pi discrimination compare with vlf detectors , it was weaker than VLF .
Best regards.

What kind of ground conditions did you use it in? Highly mineralized, or just mild ground?

Cheers

[Qiaozhi]

Hi Qiaozhi
I design and built discrimination pi detector approximately seven years ago.
It had capability discriminate between Ferro and nonferrous metals.
If pi discrimination compare with vlf detectors , it was weaker than VLF .
Best regards.

That is very interesting.
As most serious detectorists discover, it is the ferrous versus non-ferrous discrimination that is important. Discrimination between various non-ferrous targets can be useful in certain circumstances, but often it is not much more than a guess. That's why commercial detectors, that display the likely target type, are calibrated for coins, as these tend to be more consistent. The main problem with PIs being used inland is their love of iron, and (unless you're a relic hunter) this is usually what you want to avoid.

Are you willing to publish the details here?

[aft_72005]

Circuit that detects time positions of peaks and valleys in the input-voltage waveform.

http://www.edn.com/contents/images/6442431.pdf

Hi Esteban
It is notable .
Best regards.

[aft_72005]

And how successful is the discrimination when compared to a VLF-IB?

Hi Qiaozhi
I design and built discrimination pi detector approximately seven years ago.
It had capability discriminate between Ferro and nonferrous metals.
If pi discrimination compare with vlf detectors , it was weaker than VLF .
Best regards.

[Tinkerer]

Hi Max,

OK we will make a special environmentally friendly model for you.
We take this picture of the elephant, roll it up and stick it into coil.
Then we zap it with 66A current to generate a 666 Gauss B field intensity.
This should beat enough C_R_A_P out of the elephant to generate rainbow colored eddy currents.

Tinkerer

[Tinkerer]

And how successful is the discrimination when compared to a VLF-IB?

I really don't know yet. We will have to find out.
I am hoping that the discrimination capabilities will be very similar to VLF.

Tinkerer

[Tinkerer]

Hi Tinkerer,

What sort of effect does the balance between the coils have on the target response during the ON period? I would imagine that this adjustment is quite critical.

Hi Qiaozhi,
The balance of the coil is indeed the critical point.

It took me years to find ways to adjust the balance of the coil after it is cast.
I have now 3 different ways to make adjustments, all of which can be done by pots or digital potentiometers controlled by the MCU.

Tinkerer