Polish Pi

[bernte_one]

@ sbalio1

pls post your coil datas here
you have different kind of coils made
pls type here which wire diameter and how much turns (or microHenry)

what value is your damping resistor
some poeple have 180R (like me), other use 470R or 390R

did you set correct of damping resistor for each of your coil

distance so far is very good, i think you can not get more from such simple pi detector
i build 3 units by myself, work excellent from start

[dbanner]

In a previous article, he talked about a gold ring. This is what I referred to in my talk about little gold. It only takes a little sedition to understand this intention. How can there be an ostentation then we see a video. In the big treasure A gold ring considered as little gold.
The problem is in Google Translate. What is meant by the ring and the bracelet? Not the same words in translation

pi polones Not for raw gold or for finding small gold coins. Without wasting your time, it is not with this device. On the contrary, this device can be improved to work on large and medium sizes of metals .with coils of size 60cm and 1m and 1.5m
That's what we asked him, Mr. Jaick. and I answered him in this context

Yes, yes, we understand perfectly the context.

My basket coil damps out at 1k, with very good sensitivity. This circuit is quite versatile, having made a few variations, it was my favorite self-made for the wet beach sand. A nice slow and steady crawl along the beach, I detected many deep targets, mostly old crusty coins, but sometimes some nice treasure. It is still my deepest beach machine. I found coins as deep as 15-18 inches, somehow my machine loved the wet sand. My deepest target was an antique east indian bracelet found at nearly 24 inches. I dug until the hole filled up with water, my poor plastic shovel broke in half and I had to finish the dig with a large Chinese chopper that we kept for protection. This was a night hunt and I finally got the thing out of the hole, which kept filling up with water.
There are some memorable digs that are hard to forget.

Mind you, I never shielded my coil on this detector. I only ever used it at the beach. It has always been rock steady.
Now the termites are getting along well with the coil housing which was a disc shaped doughnut hole made from thin plywood and coated with varnish. Ah, those were the days.

[6666]

Now the termites are getting along well with the coil housing which was a disc shaped doughnut hole made from thin plywood and coated with varnish. Ah, those were the days.

interesting story

[dbanner]

I posted photos of the bracelet in my previous post. Had to dig it out of old collection.

And just in case someone is curious to know just what the hell a "Chinese chopper" is, well here's a pic of the beast. Believe it or not, it works good as a makeshift digging tool, kinda like a flat shovel, and a good weapon on those lonely night digs.

[Hammerhead]

Hello all This detector ominous Built from it Three copies do not work Only the crackling sound And Alkwyl are not sensitive to I don’t know where the problem isanything

[dbanner]

Hammerhead, please check out the four diodes in the charge pump circuit. Make sure they are correct orientation.

I point to the diode which I think needs to be reversed.

[Mr.Jaick]

For small gold, the best wires are the least thick
Maybe your problem in some electronic parts such as bf245a(b*c) ... lf357


coil27cm small gold
https://www.youtube.com/watch?v=wWhOMBjqe7I

coil 32*37cm gold
https://www.youtube.com/watch?v=U_Xsg1nBsFQ

coil 65cm detects 2.10 cm for a size of 30 * 35
https://www.youtube.com/watch?v=ay6jltpWRao

bf245 was fine and placed correctly, not sure about lf357 if it's genuine or just a piece of crap, seller told me it's genuine, so...
but i'm suspecting the damping resistor which i used 690 , some people recommend it! but i'm gonna change that later and see the result.
videos are good thanks

[Chiringo]

Hello all This detector ominous Built from it Three copies do not work Only the crackling sound And Alkwyl are not sensitive to I don?t know where the problem is[ATTACH]49783[/ATTACH]anything[ATTACH]49782[/ATTACH]

Dear Hammerhead
The resistance of 1M that is just above the zener if I am not mistaken is 220R
The 18k resistors above the 1000uf capacitors do not correspond either
There is indeed an error in the diodes
Can you post the board you are using?
regards

[Hammerhead]

Hammerhead, please check out the four diodes in the charge pump circuit. Make sure they are correct orientation.

I point to the diode which I think needs to be reversed.

Thank you, my friend I replaced it Diode+
TransistorThe problem is still

[sbalio1]

[QUOTE = bernte_one; 267654] @ sbalio1

pls postez vos donn?es de bobine ici,
vous avez diff?rents types de bobines faites le
type de pls ici quel diam?tre de fil et combien de tours (ou microHenry)

quelle valeur est votre r?sistance d'amortissement
certains poeple ont 180R (comme moi) , d'autres utilisations 470R ou 390R

avez-vous r?gl? correctement la r?sistance d'amortissement pour chacune de vos

distances de bobine jusqu'? pr?sent est tr?s bonne, je pense que vous ne pouvez pas obtenir plus d'un tel d?tecteur pi simple que
je construis 3 unit?s par moi-m?me, fonctionne tr?s bien d?s le d?but [/ CITATION]

J'ai utilis? cat5. 16 tours d'un diam?tre de 65 cm. 410uh. La meilleure inductance pour les grosses bobines est de 320 uh comme une bobine de 1 m. La r?sistance d'amortissement est de 1k. Dans une bobine de 1m 1,5k. . Je l'utilise actuellement dans une bobine de 32 * 37 cm et 1m. fils d'?paisseur 0,6 mm et 0,72 mm avec une inductance entre 300 ? 400uh. Fr?quence de marche de 240 Hz. ce d?tecteur est stable presque sur tous types de sols, il fonctionne avec une grande efficacit? dans ce type de sols min?ralis?s rouges ou humides. Le sol ?tait presque difficile pour de nombreux appareils tels que felezjoo pi .pim2.delta pulse1 .. mais cet appareil fonctionne en toute stabilit?. J'installe la r?sistance variable 220k dans la boite directement pour faciliter le r?glage ? chaque fois.


https://www.youtube.com/watch?v=dxh5A61Idc0
https://www.youtube.com/watch?v=MXsVHzvGV0c
J'ai apport? quelques modifications
[ATTACH] 49790 [/ ATTACH]

De plus, d'autres modifications peuvent ?tre apport?es r?alis? selon une copie de bancs de sable ... comme r?duire le temps du premier ?chantillon ? moins de 50us en augmentant la valeur des r?sistances de 33k. pour am?liorer sa sensibilit? ? l'or et ?galement augmenter la vitesse de r?ponse de l'appareil en r?duisant la valeur du condensateur 220n ? 100 ou 47n comme indiqu? sur cette photo. J'ai essay? ces modifications mais je ne les ai pas encore utilis?es sur mon appareil.
[ATTACH] 49791 [/ ATTACH]

autre test

https://www.youtube.com/watch?v=P37QlRU4g50

https://www.youtube.com/watch?v=mnx6k1-ZVEU

mod
https://www.youtube.com/watch?v=ZQScP5pC0rU

[sbalio1]

bf245 was fine and placed correctly, not sure about lf357 if it's genuine or just a piece of crap, seller told me it's genuine, so...
but i'm suspecting the damping resistor which i used 690 , some people recommend it! but i'm gonna change that later and see the result.
videos are good thanks

I used certain types of bf245 and it malfunctioned with the device because it gives the device a continuous sound which does not accelerate easily when there is a metal approaching the coil and the range was less than was necessary. Gold coins such as the ring are not detected by a coil with a size of 60 cm if you try it. but no problem with the 20 and 30 cm spool. As for gold with a diameter of 8 and 10 cm, will be detected with a 60 cm coil. with a distance of 60 to 80 cm depending on the thickness of the sample.

[sbalio1]

@ sbalio1

pls post your coil datas here
you have different kind of coils made
pls type here which wire diameter and how much turns (or microHenry)

what value is your damping resistor
some poeple have 180R (like me), other use 470R or 390R

did you set correct of damping resistor for each of your coil

distance so far is very good, i think you can not get more from such simple pi detector
i build 3 units by myself, work excellent from start

.I used cat5. 16 towers with a diameter of 65 cm. 410uh. The best inductance for large coils is 320 uh like a 1 m coil. The damping resistance is 1k. In a 1m 1.5k coil. . I currently use it in a reel of 32 * 37 cm and 1m. wires of thickness 0.6 mm and 0.72 mm with an inductance between 300 to 400uh. 240 Hz operating frequency. This detector is stable almost on all types of floors, it works with great efficiency? in this type of red or wet mineralized soil. The ground was almost difficult for many devices such as felezjoo pi .pim2.delta pulse1 .. but this device works in complete stability. I install the variable resistance 220k in the box directly to facilitate the adjustment each time.
I made some modifications to the circuit..... In addition, other modifications can be made according to a copy of sandbanks ... such as reducing the time of the first sample to less than 50us by increasing the value of the resistances by 33k. to improve its sensitivity to gold and also increase the speed of response of the device by reducing the value of the capacitor 220n to 100 or 47n as shown in the photo. I have tried these changes but have not used them on my device yet.


I am sorry for the poor translation in the previous text

[Hammerhead]

Dear Hammerhead
The resistance of 1M that is just above the zener if I am not mistaken is 220R
The 18k resistors above the 1000uf capacitors do not correspond either
There is indeed an error in the diodes
Can you post the board you are using?
regards

Hello, I built this circuit

[dbanner]

To all who built this circuit, I say to you, please read the follow up article on the sandbanks metal detector for the mods. This will give you guidance on how to get the circuit working optimum. It refers to mods to reduce the sample delay and mods to increase the response from the VCO to super fast.
Also, I used the NE5534 opamp on the front end. I did only small changes to the circuit for this chip. Which I think is more readily available than the lf357, which are usually problematic to have original chip. Many fake chips out there.

Reducing C12 from 220nF to say 47nF to 100nF makes the VCO response excellent. Really fast.

[MartyJ1963]

Hi DB,,,Which pcb did you use?,,Do you have the Layout in Sprint? Thanks, Marty