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

[ivconic]

Found the beast mkavr ... It is working fast now ... The only problem now that when unplug the coil it starts normal when i plug it it dont start and the voltage across the 12v and the 9v and the 5v drops doWn changed irf 840 but still not starting up with coil pluged i have to make another pcb thanx for help

I think it is about the coil. Most probably resistance is too low and inductance is inadequate and because of that transistor acts like a "short" junction.
Just for fast experiment on this; add in series with coil 4.7 ohms/2W (and larger) resistor. If should start than.

[selim]

new pcb drawing...
http://forum.jokerdedektor.com/pi-pu...msg834/#msg834

[Qiaozhi]

new pcb drawing...
http://forum.jokerdedektor.com/pi-pu...msg834/#msg834

It's a pity the name of the detector is spelled wrong.

[Hyena]

Isnt it different detector? 16MHz crystal, BDX54C, LF356...

[liudengyuan]

The project does not make sense, not probing depth, does not recognize the iron, job insecurity, XR-71 is far from good, do not waste your time and energy

[Geo]

Don't be so sure!!!

[freso]

I think it is about the coil. Most probably resistance is too low and inductance is inadequate and because of that transistor acts like a "short" junction.
Just for fast experiment on this; add in series with coil 4.7 ohms/2W (and larger) resistor. If should start than.

Thanx friend i will try this tonight

[Spyke]

I read the whole tread and found several PCB layouts, can somebody tell me which is the right and works with v3.30
Maybe someone can send me the files per pm including hex file.

Thanks in advance

[samii]

Hi
All PCB are working. Last pcb worked after 2-3 modification on the given forum link.

[dbanner]

Just finished reading all 44 pages of this thread and took alot of notes. Nice project. The key to success here is slow and methodical implimentation. I know someone local who has lots of LF357N chips he ordered back in the early nineties(20th century!). Would these be the one required for this project? It would seem that the Iranian author is quite clever in so far as getting people to build and tinker while he observes, debugs and upgrades his software at no cost to him with a view of perfecting the design. There is much more to this guy. I tend to give people the benefit of the doubt but perhaps that is being too naive. Insofar as the technical aspects of this design, it looks OK but certain things are hidden. The only way to know for sure is to build it, so I will try. I do not care too much about the code, only about the sampling aspect which might be retrievable and interesting.

[ivconic]

"...It would seem that the Iranian author is quite clever in so far as getting people to build and tinker while he observes, debugs and upgrades his software at no cost to him with a view of perfecting the design..."

Usually that's how things are going on.
It's a sort of mutual exchange.
He gave us working hex with trivial limitations and we are returning him experiences with the machine.
Nothing bad in that.
That's the situation with most of the hobby projects here on forum.
...
It is very good for you because you have access to larger number of LF357 chips! You will have better chances to match one with the pcb and the rest of components; to work splendid.
In his earlier claims author was very right about that fact; even from the same manufacturing series; all the LF357 does not perform equally at all, when put on this pcb!?
Pretty strange and interesting fact.
I checked that; i obtained several chips from the same series and checked them all on the same pcb: each one is giving me different debugging values!?
Sometimes those values differs much!
So it is a kind of major drawback we are having here. It needs a bit of luck to match the chip with the rest of circuitry and gain good debugging values, therefore to achieve good performances.
I tried chips from the same series, than i tried chips from the different series, than i even obtained few in metal package (so called "military" standard)...
And my final conclusion is; i don't have conclusion at all!
Because i can not establish no rule on that at all.
Some chips are matching with some pcbs and some simply don't, causing very bad behavior and poor performances.
That's a major drawback and "contra" on this project.

[ivconic]

And as always, by the "murphy's law", my first FelezJoo hand made was very good, giving me excellent debugging values and performing indeed very good in testings.
It was just random and coincidental success, somehow "most proper" LF357 was there and i put it on "most proper" pcb made at that moment, with pretty coincidental "most proper" components on it.
So at the time i was delighted and i thought it will be the same with all other hand made detectors that i will eventually make in future.
So i was more than surprised when saw here negative comments made by majority of other colleagues.
Than i made 3 more units and i experienced all the problems and issues they are mentioning on these pages.
Than i obtained also a batch of LF357's. And tested them all on few pcbs.
And than i saw that we can not pull any relevant and useful conclusion on this at all.
Only author knows what he done in the code.
Without source code we can only assume and probably be wrong.
Without more precise guidelines all this work is relying only on random and coincidental luck.
I am sorry to say this, but unfortunately it appears as truth.

[dbanner]

Murphy's law states that what could go wrong will go wrong, your first build was a success so this is contrary to Murphy's law. This project is simple enough for me to construct so I will try anyway. I think for me, It will add to my knowledge and skill. Has anyone tried using LM318 instead of LF357?

[ivconic]

Murphy's law states that what could go wrong will go wrong, your first build was a success so this is contrary to Murphy's law. This project is simple enough for me to construct so I will try anyway. I think for me, It will add to my knowledge and skill. Has anyone tried using LM318 instead of LF357?

"...Murphy's law states that what could go wrong will go wrong,your first build was a success so this is contrary to Murphy's law..."

Actually... now i am considering it as complete misfortune!
It went wrong for me actually. Because... later i wasted so much time on it trying to make another devices to work well as the first one.
If i knew from the beginning all the pitfalls and drawbacks; i wouldn't waste so much time on it at all.
But you are right; it is simple and cheap enough, so it is worth of trying anyway.

[Altair]

"...I tried chips from the same series, than i tried chips from the different series, than i even obtained few in metal package (so called "military" standard)...
And my final conclusion is; i don't have conclusion at all!

it's very strange!
Are you sure don't have some fake components? There are many of it on market!!