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

[Qiaozhi]

C4, C5, C7, C8, C9, C14, C18, C20, C21, C23, C26 - Those should be ceramic caps
C11 2,2µF - Tantalum
C6, C12 100µF - Tantalum

According the 3D image of the PCB, and the silkscreen, C11, C6 and C12 are shown as electrolytics.

[eclipse]

C4, C5, C7, C8, C9, C14, C18, C20, C21, C23, C26 100nf 2,5 MKS-02 11
C11 2,2µF 25V 1
C6, C12 100µF 25V 2

C4, C5, C7, C8, C9, C14, C18, C20, C21, C23, C26 - Those should be ceramic caps
C11 2,2µF - Tantalum
C6, C12 100µF - Tantalum

[eclipse]

One final point ... what is the range of the TX pulse rate for this detector, if it's not fixed to 200pps? I can then change the notes section on the schematic accordingly.

Frequency range 35-999 Hz
Pulse Width 100 - 500

[ossman22]

This design will never be good on low conductive targets ... not with a TX rate of 200pps, and 80dB (10,000x) gain on the preamp.

here is another new video an Iranian friend has sent it to me.
test has been down with 23cm diameter coil with gold ring
as i see in this video, felezjoo pi acts like other ordinary detectors.
not more detection depth for small targets especially low conductive items.
seems felezjoo pi designed to work just by large coils for large objects.
by watching few videos until now, in comparison, its detection depth should be same as delta pulse or xr71.
about quality of performance, we don't know much. is it stable? is it user friendly?
here is the video. 3gp format.12Mb.valid for 60 days.
download link

[bernte_one]

a short BOM
hope it helps

D1,D2 1N4148 2
D3 1N5819 1
R6, R15 10R 2
R2, R16 47R 2
R10 100R 1
R11,R12 390R >2W 1% 2
R1, R17, R21 1K 3
R7 1K5 1
R8 1K8 1
R5,R18 2K2 2
R4, R14, R20 4K7 3
R3 10K 1
R13 18K 1
R19 22K 1
R9 1M
C10 5pF Ker. 1
C2,C3 18pF Ker. 2
C4, C5, C7, C8, C9, C14, C18, C20, C21, C23, C26 100nf 2,5 MKS-02 11
C11 2,2µF 25V 1
C1 10µF 25V 1
C6, C12 100µF 25V 2
C13, C17, C25 470µF 25V 3
C19, C22 1.000µF 25V 2
C24 2.200µF 25V 1
C15, C16 4.700µF 25V 2
XTAL1 20Mhz 1
U1 Atmega328P 1
U2 LF357 1
U3 7805 1
U4 L7812 1
DIP-8 1
DIP-28 1
T1 BS170 1
T2 IRF840 1
T3 BC337 1

[giuseppem94]

[QUOTE = eclissi; 207.634] Probabilmente il tuo Surfmaster non dispone di una bobina corretto costruito. Assicurati che il tuo bobina ha parametri esatti, come induttanza e resistenza, ma più importante bassa
capacità (alcuni cavi coassiali danno maggiore capacità, assicurarsi di misurare troppo) se avete bisogno di cacciare piccole cose come monete e monete d'oro. [/ QUOTE]

what kind of wire you use? the first coil I made with the enamelled copper wire but did not work out. now I have done with a normal wire for current and detects a euro to about 30 cm while not feeling well gold

[Qiaozhi]

my dear friend
Preamplifier factor at this circuit First, with respect to capacitor 2.2 micro, Not fixed And the second is about 2,000 not 10,000 That you always repeat!
Also, when you see the frequency setting in the menu Why do you keep repeating frequency is 200?

I am not criticizing the detector per se, but merely pointing out that it will never be good on low conductive targets in its current form.

When I quickly calculated the gain as 10,000, the input was taken from the limiting diodes. If you include the 390R, then I agree that the gain is closer to 2,000. However, this is still too high for low conductive targets.

You also mentioned C11 (2u2), which incidentally is an electrolytic capacitor. This type of capacitor is well known to be a noise generator, and should never be used in a filter circuit. It would be better to completely replace this with a two-stage pre-amp (similar to the MPP). With the design as it is, you're caught between a rock and a hard place. In order to use direct sampling, the preamp gain needs to be quite high (since the Atmega ADC has 10-bits resolution), but this then limits the detector to searching for large relics. You could try using oversampling and decimation to increase the ADC resolution beyond 10-bits, but the response will become slow. Perhaps the software is already doing that ... I don't know ... which might account for the audio delay you can see in the videos.

Also note that the potential divider formed by R8 and R7 attenuates the preamp output to less than half its amplitude before being input to the ADC. This is yet another reason for looking at a redesign of the input stage.

One final point ... what is the range of the TX pulse rate for this detector, if it's not fixed to 200pps? I can then change the notes section on the schematic accordingly.

[eclipse]

Hello everyone, I have a homebuilt Surfmaster PI, I wanted to build felezjoo to have a second metal and becouse it is very simple to build, I read that the felezjoo is good for large objects, for small objects or for gold not good ?, it is true? I try to build a simple metal, preferably run by a micro but capable of good performance for small objects and gold objects (the Surmaster has difficulty with gold)
any suggestion is accepted
thanks

Probably your Surfmaster doesn't have a proper coil built. Make sure your coil has exact parameters such as inductance and resistance but most important low
capacitance (some coax cables give higher capacitance, make sure you measure it too) if you need to hunt small stuff like coins and gold pieces.

[daverave]

my surf pi has no trouble with gold and can detect 9ct wedding band at 16" whisper....the felezjoo from what i can see will be suitable for larger relic items and not small rings...the circuit is very basic amplification wise.

[giuseppem94]

Hello everyone, I have a homebuilt Surfmaster PI, I wanted to build felezjoo to have a second metal and becouse it is very simple to build, I read that the felezjoo is good for large objects, for small objects or for gold not good ?, it is true? I try to build a simple metal, preferably run by a micro but capable of good performance for small objects and gold objects (the Surmaster has difficulty with gold)
any suggestion is accepted
thanks

[daverave]

i can only see this detector being suitable for relics and not low conductive items like rings and coins.

[bernte_one]

can someone from EU Country suplly us with programmed atmega Controllers?

[koohyar]

This design will never be good on low conductive targets ... not with a TX rate of 200pps, and 80dB (10,000x) gain on the preamp.

my dear friend
Preamplifier factor at this circuit First, with respect to capacitor 2.2 micro, Not fixed And the second is about 2,000 not 10,000 That you always repeat!
Also, when you see the frequency setting in the menu Why do you keep repeating frequency is 200?

[Qiaozhi]

be interesting to see how it does on low conductive items like gold rings ???

This design will never be good on low conductive targets ... not with a TX rate of 200pps, and 80dB (10,000x) gain on the preamp.

[turboaleks]

So this detector is only recommended for a coil with large diameter? I thought i could adapt it for my requirement?! A pitty that there are only a few videos out there.