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

[6666]

It is closest to first cable from the right side.
Come to think; it is exactly the one i used, the very same cable.
I had a piece of that cable so i stripped it and pulled out those pieces, soldered together and made coil from them.
Definitely the first one from the right side!

Thanks for the cable info

[ivconic]

I was thinking at the time "if FelezJoo is done according to Minelab patent; than is logically to expect that also Minelab coils will suit it just fine".
Last time i had Minelab, it was GP3000, so i opened its coil and saw the "morphology".
They used something similar there.
Right now i am trying to find a photo on my disk...
Here it is:

[Altair]

I was thinking at the time "if FelezJoo is done according to Minelab patent; than is logically to expect that also Minelab coils will suit it just fine".
Last time i had Minelab, it was GP3000, so i opened its coil and saw the "morphology".
They used something similar there.
Right now i am trying to find a photo on my disk...
Here it is:

[ATTACH]38170[/ATTACH]

But Minelab's coil is with shield! ... or not!?
Really unshielded is better ??

[eclipse]

The shield adds more unwanted capacitance, if you can avoid it (using for example self shielding basket coil design pattern) go ahead.

[jladre]

I been using 3dss coil for salt underwater hunting and found no problem.

[ivconic]

Last summer i had Minelab Commander Mono coil for few days, to check with it.
FelezJoo PI works excellent with that coil.
It has noticeable better sensitivity on smallest targets than my diy coil.
On the other side; my diy coil is somewhat better in air distances on medium sized and large targets, in few percents maybe.
The shielding applied by Minelab in their coils is obviously much better than usual shielding applied by us the diyers in our diys.
Certain shielding coatings are not causing a rise of parasitic capacity at coil, at least not significantly, therefore there is no harm on performances.
Problem is that such materials usually are not easy available to all of us the diyers.
So we are pushed to do what we can do in given conditions, a trade offs between benefits and loses.

[Geo]

I have a 11" mono commnder but don't work for me, it gives coil error.
The Dc resistance of this coil is only 0.4Ohm.
I gave it a try with 0.6R in series with coil but again no results.
Coil works perfect on GPX5000.
Where is the problem???
Ideas??????

[ivconic]

I have a 11" mono commnder but don't work for me, it gives coil error.
The Dc resistance of this coil is only 0.4Ohm.
I gave it a try with 0.6R in series with coil but again no results.
Coil works perfect on GPX5000.
Where is the problem???
Ideas??????

That's strange?
Coil i tested was also low resistance, right now i am not sure whether it was 0.4 or 0.7 ohms, can't remember.
But it worked nice, i had never "coil error" with it.
I must be getting pretty senile because right now i am not able to tell if i put serial resistance on it or not!?
Maybe i also put serial resistance... can't recall.
Just for a test; why don't you try with higher resistance; 1 ohm, 1.5 ohm?
Or maybe there is a important difference from a coil i tested and your coil?
Can't tell for sure.

[Geo]

Maybe today make a new test with higher resistor.
With 0.6 R it works but with very bad results.

[green]

Could we get some scope pictures of amplifier out with a good and bad coil? Maybe with no target and with a target giving a half supply signal with the good coil(target spacing the same with the good and bad coil).

[Geo]

I will try today take some photos...

[Geo]

I tried yesterday with a 0.22Ohm resistor in series with commander and coil worked better but not as other coils.
A was 255 B623 C720.
One euro was detected from 25...27cm on air with sens=14 GB=5 speed=10 and delay everything between auto and 23us (13us from auto plus 10us from settings).
Will try today to do more tests and take some pictures with scope...

[ivconic]

I tried yesterday with a 0.22Ohm resistor in series with commander and coil worked better but not as other coils.
A was 255 B623 C720.
One euro was detected from 25...27cm on air with sens=14 GB=5 speed=10 and delay everything between auto and 23us (13us from auto plus 10us from settings).
Will try today to do more tests and take some pictures with scope...

Thats progress. Try with more resistance.
27cm on 1euro with sens 14 is quite alright.

[Geo]

Today i compared 3 coils.
1. ML Commander mono 11" with 0.22R in series
2. TDI 12" Dual field and
3. a Diy 40cm basket coil with L=335uH and R=0.8
With a new LF357 at frontend all coil gave about the same results
TDI coil gave the lower depth but the better numbers A, B, C
Home made coil gave the better results (it is bigger)
Commander gave better results compared with his diameter.
So i believe that the finish of this project is near if the results at the heavy field will be good.
Below will give details about results of any coil with some photos of waveforms on coil.

[ivconic]

Today i compared 3 coils.
1. ML Commander mono 11" with 0.22R in series
2. TDI 12" Dual field and
3. a Diy 40cm basket coil with L=335uH and R=0.8
With a new LF357 at frontend all coil gave about the same results
TDI coil gave the lower depth but the better numbers A, B, C
Home made coil gave the better results (it is bigger)
Commander gave better results compared with his diameter.
So i believe that the finish of this project is near if the results at the heavy field will be good.
Below will give details about results of any coil with some photos of waveforms on coil.

It makes sense, TDI coil is concentric coplanar right?
It's RX coil is smaller than at other two coils?
Also i guess it is most precise in behavior, among all three coils, right?