felezjoo PI(the best pulse induction metal detector that I made until now)

[Qiaozhi]

"... It has some "claimed" capabilities at rejecting iron, but so far we haven't seen any test results..."
Seems you missed to see my videos? Though those are only skim demonstrations which i recorded only as a reminder during the process of adjusting the detectors.
Although it is not perfect (name me any other which is perfect) it DOES rejects iron. It does rejects iron in the air and in the soil, already checked, tested and proved.

OK - I will watch the videos later before passing judgement.

10) Extreme sensitivity on smallest objects, coins, cash, jewelry (low conductive materials). - Completely opposite from what you stated here: "...and is also not suitable for low conductivity targets...".

This is an interesting statement, because the Felezjoo has a single stage preamp with a large gain, which should make it unsuitable for early sampling. What was the lowest main sample delay you were able to achieve?

[ivconic]

OK - I will watch the videos later before passing judgement.[/COLOR][/FONT]


This is an interesting statement, because the Felezjoo has a single stage preamp with a large gain, which should make it unsuitable for early sampling. What was the lowest main sample delay you were able to achieve?
[/FONT]

Possible confusion?

"...10) Extreme sensitivity on smallest objects, coins, cash, jewelry (low conductive materials)...."

To be more precise; i tested it only on coins (smaller and larger) and some pieces of jewelry which i founded handy in that moment.
It shows indeed "extreme" sensitivity on those... COMPARING to the behavior i saw with other mentioned PI diys.
But NOT comparing to dedicated VLF IB detectors, of course! This must be cleared up to avoid any possible confusion.
FelezJoo PI is NOT especially good for smallest objects and low conductive materials, yet it is real hit comparing to other PI's we mentioned here.
Of course it can not compete dedicated models from the market... like few made by ML.
But for the record, and other members who may come here and read; i had to place correction on your previous statement, because is was not quite true.
...
And yes; gain is too large. I did something about it and fixed it to work much better. Don't ask me what!
Delay... actually i can't tell; all the time during the tests Delay was set on "Automatic"... whatever that may mean.
It's all in the code. And we indeed do miss here author's presence and bit more of explanations and details.

[Davor]

FelezJoo depends upon the 8bit ADC, so something must give.
When you analyse many detectors, especially the old VLF ones, the vast majority of such detectors are built to simply saturate in a case of a strong signal. So instead of providing better ADC or compression, FelezJoo simply concentrates on the week signals. Perhaps such solution would not be my first choice, but apparently it works well.

[Speedy_G]

"...To be more precise; i tested it only on coins (smaller and larger) and some pieces of jewelry which i founded handy in that moment.
It shows indeed "extreme" sensitivity on those... COMPARING to the behavior i saw with other mentioned PI diys.
But NOT comparing to dedicated VLF IB detectors, of course! This must be cleared up to avoid any possible confusion.
FelezJoo PI is NOT especially good for smallest objects and low conductive materials, yet it is real hit comparing to other PI's we mentioned here.
Of course it..."

Hi Ivconic

Can you please tell us what distance you could detect a 1 Euro coin (International Standard comparison test for metal detectors) with your Felezjoo PI that was buried under silica-bearing sand (e.g dry beach sand - NOT air test).
I did a similar test with my Delta Pulse 2+ PI detector which I built in 2012 and I posted my results in the THunting forum. As I remember, the distance for a 1 Euro (buried under beach sand) was approximately 28 cm.
(Note that in an air-test the detection distance that I obtained was 35 cm for a 1 Euro coin).

But note that an 'air test' on coins, gold etc. does not give one any real useful information as to the efficiency/sensitivity of the PI detector. It just confuses one even more, e.g your mentioning "...extreme" sensitivity..." makes no sense.
That is the reason why I am suggesting that in future you should confine yourself to the detection of a 'buried' 1 Euro coin (but please specify the type of soil under which it is buried).

Ciao

Speedy_G

[jladre]

OK - I will watch the videos later before passing judgement.[/COLOR][/FONT]

"About the sensitivity to small target"?

This is an interesting statement, because the Felezjoo has a single stage preamp with a large gain, which should make it unsuitable for early sampling. What was the lowest main sample delay you were able to achieve?
[/FONT]

Hi Quiaozhi! Maybe you missed my video on tiny target..this is my old video and if want more distance i can made you new one.
https://m.youtube.com/watch?v=KBW5b_C717A

[green]

OK - I will watch the videos later before passing judgement.[/COLOR][/FONT]


This is an interesting statement, because the Felezjoo has a single stage preamp with a large gain, which should make it unsuitable for early sampling. What was the lowest main sample delay you were able to achieve?
[/FONT]

A example of a target with a 5usec time constant. One circuit has a 1MHz response, the other 10kHz. If sample before 9usec the 1Mhz circuit has higher amplitude, sample later the 10kHz circuit is higher. Don't know if the PI circuit acts the same.

[Qiaozhi]

Hi Quiaozhi! Maybe you missed my video on tiny target..this is my old video and if want more distance i can made you new one.
https://m.youtube.com/watch?v=KBW5b_C717A

What setting do you have for the sample delay, and what is the inductance of your coil?

[Qiaozhi]

OK - I will watch the videos later before passing judgement.

Ivconic - In the video you tested iron discrimination using a small pair of pliers. Did you perform the same test with various sizes and shapes of iron, but without changing the settings? If so, what was the result?

[jladre]

What setting do you have for the sample delay, and what is the inductance of your coil?

I havent connect this device to oscope for verifying the sample delay but in the device setting i just set it in automatic mode.. By now with that scrap diode i can detect it at 6 inches with a 8.5 inches coil 360 uH.

[jladre]

About the iron discrimination it can discriminate iron propotional to coil size..example is for a 8inches coil it can discriminate iron with a size of a plier down to the smallest. With a 60cm coil it can discriminate iron at a size of 4liters paint can..this setting is the minimum..you can set this device to discriminate large iron but you can also include some precious metal.

[Qiaozhi]

A example of a target with a 5usec time constant. One circuit has a 1MHz response, the other 10kHz. If sample before 9usec the 1Mhz circuit has higher amplitude, sample later the 10kHz circuit is higher. Don't know if the PI circuit acts the same.

The 1MHz circuit will pass the signal almost unchanged, but the 10kHz circuit responds more slowly due to the 80pF capacitor in the feedback loop, thus turning the opamp into an integrator.

Interestingly, if you remember this post ->
http://www.geotech1.com/forums/showt...228#post162228
I attached an LTSpice simulation of John Alldred's full equation minus the dimensionless scale factor (which is close to unity).

A slightly modified version is attached here, where:
t1 (sample pulse delay) = 9us
t2 (sample pulse width) = 30us
is the value along the X-axis.

There are two .step commands you can uncomment:
The upper one sweeps the sample pulse delay from 1us to 10us.
The lower one sweeps the sample pulse width from 10us to 100us.

Green - you see a similar 'delayed' response in the results where a longer sample pulse delay is used, which is effectively the same as increasing the integration time.

[6666]

And yes; gain is too large. I did something about it and fixed it to work much better. Don't ask me what!

C'mon Ivconic you cannot torture us, you have to tell us now

[jladre]

Another rough vudeo clip on felezjoo pi detecting scrap 1n4148 diode at 7 inches.https://m.youtube.com/watch?v=l5kBs0uQSXU

[Speedy_G]

Another rough vudeo clip on felezjoo pi detecting scrap 1n4148 diode at 7 inches.https://m.youtube.com/watch?v=l5kBs0uQSXU

Hi jladre

Please do not mislead the people out there, especially the amateur experimenter who is trying hard (and honestly) to build a reasonably good PI metal detector that does what its supposed to do, and that is to detect metal in a REAL situation, i.e. buried in the ground. Please see my recent post to Ivconic, essentially addressing the same problem as yours, except that he makes rather 'wild statements' concerning the capabilities of the felezjoo PI without any proof.
What you should demonstrate to us is to take a video of that same 'scrap 1N4148' but this time bury it under 7 inches of soil or sand and try again to detect it.
The test you showed us is meaningless to say the least. Luckily we are not all stupid, you know!

I am eagerly awaiting your next 'more meaningful' video...

Ciao

Speedy_G

[jladre]

Hi jladre

Please do not mislead the people out there, especially the amateur experimenter who is trying hard (and honestly) to build a reasonably good PI metal detector that does what its supposed to do, and that is to detect metal in a REAL situation, i.e. buried in the ground. Please see my recent post to Ivconic, essentially addressing the same problem as yours, except that he makes rather 'wild statements' concerning the capabilities of the felezjoo PI without any proof.
What you should demonstrate to us is to take a video of that same 'scrap 1N4148' but this time bury it under 7 inches of soil or sand and try again to detect it.
The test you showed us is meaningless to say the least. Luckily we are not all stupid, you know!

I am eagerly awaiting your next 'more meaningful' video...

Ciao

Speedy_G

Hahaha!! It that so speedy-G? If it is buried inthe white sand detection still the same and if in black sand it detect at 4-5 " below..im not misleading her. I just demonstrate the capability of this pi.. In iranian forum you see more video there using large coil that detect big target at 3 meters below tge ground.. If you dont believe the capability of this pi then leave it. Its non of your business!
Goodluck!