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

[Geo]

μια έξυπνη λύση του ...: Lol:

[Geo]

Some times i see that the display shows negative prices at the signal power (when there is n't objects near to coil). When this is happening it gives thin beeps...
Any idea why???

[ivconic]

Some times i see that the display shows negative prices at the signal power (when there is n't objects near to coil). When this is happening it gives thin beeps...
Any idea why???

It is excellent feature and in your case it displays "underbalanced" state. Negative values are soil signals aka it is not perfectly GEB-ed.
Here is what you gonna do;
1) Lower the coil to 10cm above soil surface,
2) Keep it calm, hold it tight and don't move,
3) Press "Down" button to GEB,

It is now balanced to soil conditions with coil just 10cm above the soil.
On the display it should read zero... or displays nothing.
Now:
A) Rise coil up to 50cm above the soil and observe the numbers changing,
B) Lower coil down to 1-2cm above soil and again observe the numbers changing...



You get it now?
...
It will give you maximum stability and performances as far as you maintain those "numbers" as closest to position where it was GEB-ed last time.
Είναι αυτό σαφές?




P.S.
My previous long term experiences in work with Cscope 1220B made me very adaptive and "got used" on this kind of metal detector behavior.
That's why it was so easy for me to quickly understand and adapt on this FelezJoo PI detector.
Cscope1220B in "Meter&Audio Discr." mode is producing "positive and negative" audio tones if signal goes out of "range".
"Range" is previously defined by Ground&Retune knobs and that "range" directly is dependable on coil position relative to soil surface at moment of taking the ground sample by pushing Ground knob and later on retuning by pushing Retune knob.
Although Cscope1220B and FelezJoo PI are having nothing in common; yet they behave similar in described situation.

[ivconic]

Important to emphasize; this is typical behavior for all non motion type machines.
You can actually hear (Cscope1220B) and see (FelezJoo PI) relation between previously taken ground sample and present situation at signal.
As far as i experienced; FelezJoo PI will allow you some +5% / -5% deviation from ground sample before it starts with LCD indication.
Which is alright, you can't hold the coil always at same distance from soil surface, it is almost impossible in real searching.
If i remember correctly Cscope 1220B was less tolerant than that.
But than again; that's the main advantage at non motion detectors, at least for me.
Because you can literally feel and "sniff out" for delicate and weak signals, working like that, signals which are non existent for motion type detectors most of the time.

[ivconic]

Inspiration is falling like a rain now!
Pay attention on this:

"... if signal goes out of "range"... "Range" is previously defined by... As far as i experienced; FelezJoo PI will allow you some +5% / -5% deviation from ground sample before it starts with LCD indication..."

White's 6000 Pro XL (Spectrum, XLT,Eagle IIC... many White's models more) will give you a "feature" more!
With those you can make the "range" more "tolerant" , wider or narrower in process when taking Air and GEB samples separately!
There you can perform a little trick and take Air&GEB samples with desired "deviation"... simply by rising/lowering coil at desired level, different than advised in manual.
This need a bit of experience, lot of trials&errors, but it can give you hell of performances in certain moments and under the certain conditions.


P.S.
Use your imagination now and try to apply the same at FelezJoo PI.

[Geo]

Thanks Ivica,
The negative value happens when i have the coil stable 1m above the ground inside the lab and make tests.
Anyway from what i read you have right because at version 3.35 this is a way to check caves,but i did n't finish it yet.
Until now i was busy so no time to make coils but now started the winter, much rain and much cold.
Let connect the soldering guns at sockets...

[basellafe]

Iwant to thanx this site for the all services that help ever in this hoppyest im going to collect this project and i have a question when programming atmega328 p with arduino as isp should i upload a boot loader to atmega and another question about fuses should i leave it as manufacture or change it.thanx for help

[Geo]

Yes, I've been experimenting further, and my 300uH coil mostly shows 19us delay and sometimes 18us.


Here's a photo of my Felezjoo -> [ATTACH]36057[/ATTACH]
I designed a new layout that has the tactile switches on the PCB and/or off the board. Plus the LCD was meant to mount on top of the PCB, as shown in this 3D representation -> [ATTACH]36058[/ATTACH]
However, the available capacitors were taller then expected, and the LCD pinout was different. Hence it was mounted on the end. It was only an experimental PCB anyway, so no problems.

With my 300uH coil I managed to get some settings that will reject an iron bolt and accept several coins, but some silver coins were then a bit iffy. I also probed the TX oscillator signal with the scope. I was expecting to see sets of pulses, maybe varying in width (after seeing your scope shots) but the pulses are actually all the same width (as set up in the menu). It seems that your PC scope is having a problem sync'ing because there are gaps in the transmission, presumably because the processor is busy doing something else, such as updating the display. As far as I can see so far, there's nothing magic going on here. It's simply some sort of conductivity discrimination based on sampling around the decay curve. The Earth field rejection works very well though. Also need to try the ferrous discrimination with different sized targets.

The interesting thing that has come out of this is that the LF357 is quite a lot faster than the NE5534 (or NE5532). However, comparing a single-stage preamp with an LF357 against a NE5532 as a 2-stage preamp, there is little difference if any.


I'm not sure where you could possibly be measuring the actual sample delay for this detector, since it uses direct sampling, and hence the actual sample delay is hidden in the software. I suspect you are looking at the preamp output, and making a presumption from there. In which case the value displayed on the LCD is most likely the correct one. With a 16us sample delay, any target with a TC of less than 3.2us will have completely died away before sampling takes place. As far as I can ascertain, the detector continuously changes the sample delay, not just at switch-on, by checking when the preamp comes out of saturation. You can see this yourself by placing the coil near some metal, and then displaying the delay setting by pressing the Down button.

I also tried detecting a 5mm square of aluminium can (sent to me by Nupi, along with some hypodermic needles after an earlier discussion) and it was undetectable, even when using the settings you supplied. Then I cut my own small aluminium square, this time 10mm x 10mm, from a Schweppes Tonic can. This was cut from the side wall, and had a thickness of 0.1mm. Even trying many different menu settings, the best result was about 5mm detection distance with the target close to the actual coil windings.

At the moment I don't know what the relationship is between integw and sensitivity, but they appear to affect each other. It seems that integw is maybe the amount of averaging (integration) applied in software, and lower values give a sharper response.

I also tried increasing the frequency to its maximum value of 999pps, and reducing the TX pulse width to its minimum of 100us, in the hope of getting a shorter sample delay. However, the results was much the same.

In order to get consistent results, I suggest that everyone check the thickness of their 5mm aluminium square target. As noted in another thread, the material in the top and bottom of a soda can is substantially thicker than the side wall. I remember from some calculations I did previously that target thickness makes a huge difference to the TC.

Qiaozhi, how is the depth of the detector compared with the minipulse??
I am interesting for coins or bigger objects as soda can, not for small al pieces.

Regards

[Qiaozhi]

Qiaozhi, how is the depth of the detector compared with the minipulse??
I am interesting for coins or bigger objects as soda can, not for small al pieces.

Regards

Hi Geo,

For the last few weeks my Felezjoo board had mysteriously vanished. But while looking in a box for an HDMI cable, I discovered it in the bottom. It must have fallen off the table and lodged itself in the corner. Personally I never really liked the Felezjoo. The only good thing about it was the fast preamp, which could be useful in another design. I'm not at home at the moment, but maybe tomorrow I can run a quick comparison test with a soda can.

[Geo]

Thanks Qiaozhi, i wait.
I am interesting for it because it is a no-motion detector and i can use easy big square coils and has good GB as you wrote.

Regards

[Qiaozhi]

Thanks Qiaozhi, i wait.
I am interesting for it because it is a no-motion detector and i can use easy big square coils and has good GB as you wrote.

Regards

I have tested the Felezjoo with a 7" diameter mono coil, and the soda can was detected at around 16" max, but the threshold was very jittery. Basically, I'm still not impressed by this detector.

Next I was going to do the same test with the same coil using an MPP. However, I'd forgotten that all my MPP boards have been modified during a series of experiments, so it wouldn't be a fair test to use one of those. Therefore I connected up a Geotech Baracuda REV-A, and the soda can was positively detected at 21". This was with the same 7" coil. I would expect the MPP to give a similar result if it was using the same TX pulse width and pulse rate.

[ivconic]

I have tested the Felezjoo with a 7" diameter mono coil, and the soda can was detected at around 16" max, but the threshold was very jittery. Basically, I'm still not impressed by this detector.

Next I was going to do the same test with the same coil using an MPP. However, I'd forgotten that all my MPP boards have been modified during a series of experiments, so it wouldn't be a fair test to use one of those. Therefore I connected up a Geotech Baracuda REV-A, and the soda can was positively detected at 21". This was with the same 7" coil. I would expect the MPP to give a similar result if it was using the same TX pulse width and pulse rate.

Would be good if you provide here more details;

1) A,B and C debug numbers on your copy of FelezJoo PI,
2) All the MENU adjustments you did on it before testing.

Because i highly suspect that your setup is optimal. Simply because i achieve much different result with my 8" coil. Cola can at ~45" with clear audio response.
Most probably you haven't made proper coil, that's the common reason for poor performances.

[Qiaozhi]

Would be good if you provide here more details;

1) A,B and C debug numbers on your copy of FelezJoo PI,
2) All the MENU adjustments you did on it before testing.

Because i highly suspect that your setup is optimal. Simply because i achieve much different result with my 8" coil. Cola can at ~45" with clear audio response.
Most probably you haven't made proper coil, that's the common reason for poor performances.

If you post the settings you used to achieve 45" on a cola can, plus the details of your coil and the value of the damping resistor, I will set up my circuit the same way.

[ivconic]

You are not giving me answers on my questions; instead you are asking me your questions.
Is it so hard to answer on my questions here?

[ivconic]

Would be good if you provide here more details;

1) A,B and C debug numbers on your copy of FelezJoo PI,
2) All the MENU adjustments you did on it before testing.

Because i highly suspect that your setup is optimal. Simply because i achieve much different result with my 8" coil. Cola can at ~45" with clear audio response.
Most probably you haven't made proper coil, that's the common reason for poor performances.

Again, please answer on these.