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

[Qiaozhi]

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. (reply 1152)

45 inches with a 20cm coil, almost 6 times the diameter

Yes, you are correct. That quote was from post #1152.
Then there was a later quote in post #1159 which referenced a 39cm coil.

Let's wait and see what Geo manages to achieve with a new coil.

[Qiaozhi]

For when I get my felezjoo-pi working what numbers are you trying to get to
or closer to ?

In the system settings -> http://felezjoo-pi.blogspot.co.uk/20...-settings.html
it states: A=300, B=700, C=800

[ivconic]

For example, this one is done indoor with Sensitivity set at 14.
I couldn't record the maximum detection distance for this target because i could't reach that far with one hand and at the same time carrying the camera in another hand.
And at the same time i am sitting there close to coil trying to show as much as i can in a single shot.
So you can see on this video only 50-60cm detection distance from a target.
But trust me it was almost 1 meter detection distance at that moment.
BTW that was the mentioned 39cm coil...

[6666]

In the system settings -> http://felezjoo-pi.blogspot.co.uk/20...-settings.html
it states: A=300, B=700, C=800

Thank you, thats good info.

[Geo]

Yesterday i constructed a new basket coil. Details are D = 40cm, L = 335uH, R = 0.8Ohm.
This coil is more sensitive so now i can not test it inside the lab with sensitivity more than 14.
The 3 numbers are A..358, B..632, C..723. Auto delay is 11us. With GB = 5 and Sens = 14 it detects at air a sodacan at 72cm with constant signal.
Also a 1euro coin at 30..31 cm and a One Penny at 36cm.
I believe that out of lab with sens at 18 ... 20 will take about 20% more. So it is a very deep detector.
Maybe today or tommorow if weather is good to go at field for test and to inform here.
Also i want to construct another basket coil with L = 400uh. To do this i will add (by soldering) 2..3 turns more to existing coil.

[ivconic]

[Geo]

Finally today i went at test field.
At #1175 wrote about the new coil.
At field there is a soda can buried at 60cm depth and another one at 80cm depth.
Sensitivity was 16, delay=14 auto delay 11 (so i believe that the delay is 25us).
Speed =10 and gb =1.
Soil was very wet and very heavy
Felezjoo catches the can at 60cm depth with the coil 30cm above the ground. Very good...a bit better than my TDI with 60cm coil....
After it i tried the can at 80cm depth. Yes.. no problem and with it... but with coil near to soil.....
Problems..... Not stable , i needed to press the down button very often. If i will not find the solution for the unstable then this good detector is not usefull
Maybe i need to play more with settings and why not to make another coil..

News..... soon.

[ivconic]

Finally today i went at test field.
At #1175 wrote about the new coil.
At field there is a soda can buried at 60cm depth and another one at 80cm depth.
Sensitivity was 16, delay=14 auto delay 11 (so i believe that the delay is 25us).
Speed =10 and gb =1.
Soil was very wet and very heavy
Felezjoo catches the can at 60cm depth with the coil 30cm above the ground. Very good...a bit better than my TDI with 60cm coil....
After it i tried the can at 80cm depth. Yes.. no problem and with it... but with coil near to soil.....
Problems..... Not stable , i needed to press the down button very often. If i will not find the solution for the unstable then this good detector is not usefull
Maybe i need to play more with settings and why not to make another coil..

News..... soon.

Bravo!
See what i meant?
I told you!
...
Yes with earlier versions bellow version 3.23 i also noticed instability.
But with version 3.23 and above that problem is fixed nice.
No more instability.
Also i should remind you on one important thing at coil; DON'T make any type of shielding or "Faraday cage" over coil!
You can use shielded cable though, from coil to detector housing.
But leave the coil itself unshielded!
And flash version 3.23 or any above.
You will be even more satisfied!
Cheers!

[Geo]

Hi Ivica.
My coil is basket type unshielded.
I use the version 3.35 and i don't know what is wrong and it is unstable.
Maybe must work it at lower speed and higher GB so SAT to has the ability for faster response.... (my idea).
Who are your settings??

[ivconic]

Hi Ivica.
My coil is basket type unshielded.
I use the version 3.35 and i don't know what is wrong and it is unstable.
Maybe must work it at lower speed and higher GB so SAT to has the ability for faster response.... (my idea).
Who are your settings??

Settings are default, as they are after fresh Atmega programming.
Only Sense risen to 18 when outdoor.
...
I am not sure about basket coil, i made 2 of those and i don't like them at all. Not deep.
My 39cm coil which showed the best performances is ordinary coil, only made from pvc coated litz wire.

[ivconic]

I searched through my archives and luckily i founded few photos of coil before potting!
I have that habit of taking photos on each of my works, nice habit!
You'll notice different colors of wires; that's because i hadn't a wire in its entirety so i used pieces soldered together and isolated.
Those are the pieces of wire taken out from some random cable.
That's the best coil i made so far for this detector. Extra deep and pretty stable on ground.

[6666]

My 39cm coil which showed the best performances is ordinary coil, only made from pvc coated litz wire.

When you say litz wire, do you mean multi stranded tin plated copper wire,
or real litz wire which is multi stranded but each wire is insulated from each other ?

[Geo]

Thanks Ivica.
So now must look for new isolated wire.
I suppose that something betwen 0.65 and 0.8 will be OK.

[Geo]

You'll notice different colors of wires; that's because i hadn't a wire in its entirety so i used pieces soldered together and isolated.
Those are the pieces of wire taken out from some random cable.

Hahaha... .also i do the same

[ivconic]

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!