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

[mohamadreza26204]

FULL pcb

https://filebin.net/hafzvu2vyim834qu

[ionut_mtb]

Talking about using this detector on the beach/underwater saltwater, i have few questions that intrigue me:

-will it work underwater without giving coil error?
-wet sand will give false signals?
-why we don't use +vcc as ground on pcb and coil?

Why using it? because is simple design, because is deep and sensitive, a bit unstable although (coil need to stay as parallel as it gets with the ground.
Share your thoughts. Thanks

[sabios]

They gave me this image, it's fine, so I mean the pulses in the bs170 and the irf840

[sabios]

but I checked the pins of the bs170 with an lcr checker and everything is correct, so I don't find the problem since in gate it is fine but in drain it is wrong, it seems inverted.

[BC547]

@sabios:
Since felezjoo is largely the same as Pickini - the main difference is voltage sampling vs temporal sampling:
The pulses you measured at gate and drain of the BS170 look OK: inverting level shifter 5V->12V.
The only problem I ever heard of with the BS170 is that there are components with different pinout:

https://www.geotech1.com/forums/showthread.php?23400-PICKINI-V4-an-easy-to-build-self-adjusting-PI-detector&p=223458#post223458

But this other pinout does not result in a correct pulse inverter like you have.

[sabios]

These are the data that I obtained in gate and in the output it seems that if I have the pulse but in the output it does not seem correct for that reason some replacement for bs170

[Krzysztof]

The first letter P stands for picopower series, the remaining U is equivalent to PU.
Source here:

https://forum.arduino.cc/index.php?topic=561928.msg3890391#msg3890391

[sabios]

One question, I recorded another chip but it came out more or less the same result, there is some difference between the ATME328P-U and the ATMEGA328P-PU and I am also using the extremeburner to record it.

[ivconic]

If there is no pulse at TP3; obviously the chip is not generating it, or...
Most trivial reason; TP3 is by mistake inadvertently short-circuited.
If not the case; than chip is faulty.
Or... the code in chip stopped to work properly due some over-counter protection.
Small oscilloscope that you have is good enough to check these things.
First make sure that TP3 is not short-circuited.

[Carl-NC]

There is no way I can tell you what is wrong. You'll need to troubleshoot, start with the micro and find out if it is working or not.

[sabios]

I was able to check and indeed the BS170 is not the problem, it is that there is no pulse in the Gate in the BS170, but then what would be the error, by the way, I will upload the image of the pcb that occupies the diagram as well.


If you could tell me if it is because of the pcb or something else, I would appreciate it.George FelezJoo-PI - Schematic.pdf

[Carl-NC]

You need to figure out a way to check for proper pulses. Building metal detectors requires an oscope of some kind. I don't know anything about the one you show but my experience with similar devices is (1) they are not very good and (2) they are better than nothing at all.

[sabios]

I don't have but they think this one works for me since it's small but I don't know how good it is

[Carl-NC]

The voltages are close enough.
Do you have an oscilloscope?

[sabios]

check the voltage in the 7812 there is 12.2 and in the 7805 there is 5.1 they think that is the cause or is it the atmega328