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

[useus]

they asked me for the photo of the original LF357, the public for information purposes for those who need to see the difference with the fake ones

[Suvabard]

to build the pinpointer I used a 25mm diameter plastic tube to which I wrapped 139 turns of awg24 over 25mm in length at the end of the tube taken from an ethernet cable (it takes some inventiveness to separate it from the pair).
Result: inductance and resistance equal to my research coil.
Obviously, an RG58 cable with connector must be connected to the pinpointer to connect it to the felezjoo instead of the search coil.
Later I load the photo

Nice work useus! Thanks for sharing.

[useus]

[useus]

Yes! Please give us more info!

to build the pinpointer I used a 25mm diameter plastic tube to which I wrapped 139 turns of awg24 over 25mm in length at the end of the tube taken from an ethernet cable (it takes some inventiveness to separate it from the pair).
Result: inductance and resistance equal to my research coil.
Obviously, an RG58 cable with connector must be connected to the pinpointer to connect it to the felezjoo instead of the search coil.
Later I load the photo

[Suvabard]

if someone is interested I built a pinpointer to be connected to the felezjoo instead of the coil, without any modification to the resistors / potentiometer the pinpointer coil has the same values as the search coil (350uH - 1 ohm), it is enough to disconnect one and connect the other also on the fly, it keeps the same debug values and discrimination also works !!!

Yes! Please give us more info!

[useus]

if someone is interested I built a pinpointer to be connected to the felezjoo instead of the coil, without any modification to the resistors / potentiometer the pinpointer coil has the same values as the search coil (350uH - 1 ohm), it is enough to disconnect one and connect the other also on the fly, it keeps the same debug values and discrimination also works !!!

[useus]

great! Did you notice particular performance with this number/settings?
can you explain what are the other adjustments for B&C numbers?
thanks

I have no way to try it on the field until the end of the month, unfortunately I am injured and I cannot move, if there are substantial differences I will let you know even if I do not think there is a visible difference, before I had the values not perfect but very close (300 698 803). Value B I noticed that varies by changing impulse,
also the value C but is much more stable, the problem is that it also varies with A so I put a 470ohm potentiometer in place of R11 to be able to adjust it at will even changing the pulse value. I obtained the perfect C value using a coaxial cable,
unfortunately I can't tell you the model because nothing is written but looking at it I'm almost sure it's a RG58

[ionut_mtb]

After a war to the death with resistances, potentiometers and various cables, here is perfection!

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[ATTACH]48253[/ATTACH]

great! Did you notice particular performance with this number/settings?
can you explain what are the other adjustments for B&C numbers?
thanks

[useus]

After a war to the death with resistances, potentiometers and various cables, here is perfection!

[Rodelio]

thanks Tinkerer. Very good information in that site. Now i wonder, Did somebody in the forum test the AD825 instead LF357 in this felezjoo proyect in particular? I will like to know the results to order this operational amplifier.

[useus]

Is there a way to turn off the sound of the holes?

[Tinkerer]

https://www.eevblog.com/forum/projects/lf357-substitude/

[Rodelio]

Anyn progress with the LA3130? . My Felezjoo its fully functional. ?Just only i cant find any original LF357 here in my country. iI have friends travelling to Per?, Ecuador, Chile, Panama. etc., They only found fakes ics from cheneeses. My last hope is EEUU. If some friend could helpme to catch at least one original lf357(no matter with short legs), i will be eternally gratefull.

[useus]

which is the best capacitor type for C14 and C26? actually i use MLCC but I think we could improve with another type.

[useus]

out of curiosity is there a list of ids and related metals?