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

[bernte_one]

hi pigeon, i just have some x ray photos in my deepest archives, made from a friend which had contact to a dentist or another local doctor which has xray machine for medical use
we get this photos for free

its very simple, for example you have a fixed damping resistor on detector pcb maybe 1K 1W and another direct in the coil for tuning (also a fixed)
both are in the end parallel to coil
if you have 1k on pcb and 1k on coil your total damping value will result in 500R
to achive 450R damping resistor: pcb 1K and coil 820R (E- Resistor line)

https://www.digikey.de/de/resources/conversion-calculators/conversion-calculator-parallel-and-series-resistor

[useus]

i think the simplest solution is to set a variable damping resistor to your setup
then make a decision which coil ist your favourite and set it with the damping resistor to the right value
when right specs found you can add a damping resistor direct to coil and not at pcb

then try and if it works for your mod your other coils to

lorenz coils are made the same way, every coil shape has it own damping resistor at the solder connections in the coil enclosure

having and using three different coils, all I can do is use the potentiometer

[pigeon]

[QUOTE = bernte_one; 266234] Je pense que la solution la plus simple est de r?gler une r?sistance d'amortissement variable sur votre configuration,
puis de d?cider quelle bobine est votre pr?f?r?e et de la r?gler avec la r?sistance d'amortissement ? la bonne valeur
lorsque les bonnes sp?cifications ont ?t? trouv?es, vous pouvez ajouter un r?sistance d'amortissement directe ? la bobine et non au circuit imprim?,

essayez et si cela fonctionne pour votre mod, vos autres bobines ? bobines de

Lorenz sont fabriqu?es de la m?me mani?re, chaque forme de bobine a sa propre r?sistance d'amortissement au niveau des connexions ? souder dans le bo?tier de la bobine [/ QUOTE]


thank you very much

have you pictures for more better understanding

[bernte_one]

i think the simplest solution is to set a variable damping resistor to your setup
then make a decision which coil ist your favourite and set it with the damping resistor to the right value
when right specs found you can add a damping resistor direct to coil and not at pcb

then try and if it works for your mod your other coils to

lorenz coils are made the same way, every coil shape has it own damping resistor at the solder connections in the coil enclosure

[useus]

i can run no counter version at sens 19 inside apartment without problem and good depth. Only with shielded pcb and detech coil for gpx. But these shield and coil shield/resistance/inductance is not perfect for felezjoo pi as for Mr Hamid (designer). I had read all 2600pages from iranian forum with google translate and you have alot to learn from there.

after the tests I did I can assure you that the no counter version has stability problems.
my pcb is also shielded
use spider coil 349uH 1.1ohm unshielded, flat spiral coil 350uH 1.2ohm shielded and 380uH 0.9ohm pinpointer coil unshielded all DIY


with demo 3.35 hex no stability problem 18/20 sensitivity
with no counter hex stability problems from 12 up sensitivity


in practice hex 3.35 full edit works but is not reliable, there is probably protection in the code

[ionut_mtb]

I found that 3.35 full edit no counter is not absolutely stable.
doing the tests in the air the 3.35 full edit must be below 12 of sensitivity in order not to give false signals, instead the original 3.35 demo can safely work without false signals at 18 of sensitivity.
all tested with the same setting parameters and fixed metal detector in the same position.

i can run no counter version at sens 19 inside apartment without problem and good depth. Only with shielded pcb and detech coil for gpx. But these shield and coil shield/resistance/inductance is not perfect for felezjoo pi as for Mr Hamid (designer). I had read all 2600pages from iranian forum with google translate and you have alot to learn from there.

[useus]

I found that 3.35 full edit no counter is not absolutely stable.
doing the tests in the air the 3.35 full edit must be below 12 of sensitivity in order not to give false signals, instead the original 3.35 demo can safely work without false signals at 18 of sensitivity.
all tested with the same setting parameters and fixed metal detector in the same position.

[Boadil]

hello and happy new year!

[ionut_mtb]

Happy New Year !


Ionut, can you tell for us at which PPS and pulse width you drive your flat coil?
As for compartion my clone pi-w coil-target distance limits are - 35cm for 26mm coin (1 gryvna) with flat coil 27cm, with PPS 200, pulse width 100uS.


Thanx!

hello and happy new year!

i’m not at home right now to see the exact Settings but from what i remember frequency was 201 (on felezjoo iranian forum they say it is less noise affected) and PW different from coil to coil, influenced by coil resistance. For example for my homemade flat coil r=~1.9 ohm i use less PW ~ 135 to match number A 300. For detech spiral 11” ultra sensing gpx coil R=~0.4ohm i had to push PW more ~180 to get A 300. Detech coil is more stable and deep. But did not had the time to test in the field.

[Vadim18]

Happy New Year !


Ionut, can you tell for us at which PPS and pulse width you drive your flat coil?
As for compartion my clone pi-w coil-target distance limits are - 35cm for 26mm coin (1 gryvna) with flat coil 27cm, with PPS 200, pulse width 100uS.


Thanx!

[SWL]

Thanks for the information ... Today or tomorrow I will wrap the sensor and check .. But I won’t figure it out with backlight --- I’ll connect constant power

[ionut_mtb]

One more question ... I'm going to make a basket sensor. Size 190 mm. I’ll look for small things. Has anyone already walked with such a sensor?
[ATTACH]48972[/ATTACH]

i’ve tested yesterday flat coil/ debug numbers almost perfect, air distance for a coin aprox 35cm. But in the field i had a lot of false signals, only way to silence the detector was to adjust speed from 10 to <5 but depth become very low. I think shield of the coil is the problem. Basket coil give best depth/sensitivity but you need to test. Depending on the coil size you have to use the right wire to match resistance and inductance. I saw that inductance is more important as for the resistance, you can adjust PW to get the best debug numbers. Minelab gp coil also works but not yet tested in the field.

[ionut_mtb]

Voltage varies from 0 to 3.75 at pin 15 of LCD. If apply directly 5v to pins 15 and 16 --- the backlight works. I will do a separate power supply through a resistance of 100 ohms ...
[ATTACH]48945[/ATTACH]

Backlight varies only if volume is off and target is near the coil. I’m not sure about your problem, it might be something to do with fuses when writing atmega chip.

[SWL]

One more question ... I'm going to make a basket sensor. Size 190 mm. I’ll look for small things. Has anyone already walked with such a sensor?

[SWL]

Voltage varies from 0 to 3.75 at pin 15 of LCD. If apply directly 5v to pins 15 and 16 --- the backlight works. I will do a separate power supply through a resistance of 100 ohms ...