SBG- slow motion metal detector

[Ruben2000]

Thank you so much, SCS-bg, for sharing your schematic. I'm going to build your detector and test it in the field. I'll take some time to make the single-sided PCB. Your video intrigued me, showing how the sound varies with different metals and how it discriminates between them. I think building it will help me understand its operation better. Thank you so much for your contribution to this forum, and we hope you get well soon!

[ivconic]

This is a great "brain teaser" for me on this boring evening!
I "decoded" most of the pcb.
But there are a few parts that I haven't been able to decipher and need some help here.
I also found a couple of inconsistencies between the schematic and the pcb. I marked everything.
BTW my schematic is bad and will need a lot of fixes, so ignore it!
Instead of clarifying things; I made even more confusion with my schematic!

In the attachment, I provide a Sprint Layout pcb layout on which only need to write down the values of the components that I have not been able to decipher.
I also make a few remarks on the original schematic.
CLICK TO ENLARGE:




P.S.
If nothing else; at least I really enjoyed "brainstorming" and practicing focus, which I've lost quite a bit lately!

[scs-bg]

I think you are working on this board in vain. I made it myself with an iron according to my ideas. In practice, many changes were necessary. This is a test board of this design. The elements are soldered additionally. No one is a prophet in electronics. For example, the diode limiter at the input of the TL 061. No one can predict that the amplifier has a trigger effect when a signal with a large amplitude has a trigger effect. The circuit that I have sent is final and working. Maybe if I had decided to produce, I would have redesigned the board. Now I have no such intention. You can only be happy that I have done the hard work.

[scs-bg]

You need to know that the circuit had a small drift of the discriminator when the stabilizer was transistor. With an integrated one there is no such problem. The circuit has also been tested with DD coils with excellent results. There is a problem when working with coils with small inductance, for example omega and coplanar. Then changes are needed in the generator.

[scs-bg]

The board also includes circuits for compensation of the received signal, which turned out to be unnecessary. However, many beginners will have a hard time dealing with this. Do what you see on the diagram and you will be satisfied. If you do something different, you will get many related problems.

[scs-bg]

Ivkonic correctly noticed that the 470nF C7 capacitor in the generator is connected to minus. I made a mistake when drawing the circuit with the program.

[scs-bg]

A separate diode limiter is needed at the input of the TL061 to prevent leakage currents in the control of the PN4393. Without the diodes D2 and D3 as on the board it also works. But not as well.When connecting the input of the TL 061 directly to the output of the operational amplifier without a limiter, a trigger effect occurs. So this is what works best.

[scs-bg]

This is the schematic of this board. Many things are different.

[ivconic]

"...I think you are working on this board in vain..."
No, it is separate hobby for me, to "brainstorm" the sketches.
Now I get it right, thanks for clarifying.
The most proper is the neat schematic you posted earlier ("2026") , but with only one small correction; the 470nF goes to minus instead the ground.
If is that so; than new pcb must be drawn.
Another brainstorm! Fun!

[scs-bg]

This schematic, which is hand-drawn, is a schematic of the board you're working with. It was an experimental board. I wanted to help you. But the design underwent changes that you see on the 2026 schematic.

[scs-bg]

We live in the Balkans, we are Slavs and we can't understand each other, maybe because I don't know English well, I studied German.

[scs-bg]

Well done, you are very persistent. You will get a very good result if you completely change the board according to the 2026 scheme. With a stabilizer integrated circuit

[ivconic]

Yes, the English language does not match 100% with the way of thinking of the Slavs.
I learned that living in Greece, I learned the Greek language much easier and faster, just because throughout history we have been mixed a lot and were close,
even though the Greek language is 100x "harder" than English, but actually it is not.
Because the mentality is similar and the way of thinking and assembling thoughts into sentences is quite similar between Serbs and Greeks.
And the Bulgarian language is of a small difference from the Serbian language, and I quite understand Bulgarian.
If I lived in Bulgaria; I think I would learn that language perfectly in a couple of months.
Language has direct connections with the brain and way of thinking. Few people "deeply" think about it, except professional philologists and translators.
Literal translation from word to word often does not give accurate results and often completely changes the meaning of the sentence and thought.
And here we don't just use plain English, but "technical" language is involved, which is specific and somewhat more difficult than ordinary everyday English.
But I only recently discovered the biggest mental differences in converting thoughts into language, a couple of years ago, when I started working with a colleague from China.
Despite AI and despite highly advanced online translators; very often I have to change the order of words in a sentence several times in order to get a meaningful message that
I want to send to my colleague from China... and vice versa.
At first, for the first couple of weeks, it was hilarious!
We didn't understand anything correct each other! We often "offended" each other fiercely! Ahahahahahaha!
It should have taken at least a month for both of us to realize that the translator was a big obstacle between us!
And then it became clear that it is a matter of mentality and how the brain works.
This is a long post, off topic, but very interesting to mention.
Maybe my posts are so long and tedious sometimes; because I realized that many will not understand the messages properly; if I don't write a small "novel" in the post,
with many details and explanations.
This is not necessary for English-speaking colleagues, they understand "Tarzan language" very easily.
But this is still an international forum, many people look at these topics and I mainly go into detail for them.
An interesting little story about languages and the way the brain works...

[ivconic]

Yes, I will look at the pcb design in the next period.
I have a nice box from Bulgaria, I think it is a type box for "Golden Mask".
I'm just measuring the internal dimensions, to see how big the pcb needs to be.
The dimensions are not large, so drawing the pcb will be a little more complicated.
I will have to give up my favorite dimensions of 7.5mm for resistors and diodes.
I will use 2.5mm for both resistors and diodes and maybe 5mm in some places, where the situation allows.



Here is the Sprint Layout template for the pcb that fits into this box:

[GeoMax]

Yes, the English language does not match 100% with the way of thinking of the Slavs.
I learned that living in Greece, I learned the Greek language much easier and faster, just because throughout history we have been mixed a lot and were close,
even though the Greek language is 100x "harder" than English, but actually it is not.
Because the mentality is similar and the way of thinking and assembling thoughts into sentences is quite similar between Serbs and Greeks.
And the Bulgarian language is of a small difference from the Serbian language, and I quite understand Bulgarian.
If I lived in Bulgaria; I think I would learn that language perfectly in a couple of months.
Language has direct connections with the brain and way of thinking. Few people "deeply" think about it, except professional philologists and translators.
Literal translation from word to word often does not give accurate results and often completely changes the meaning of the sentence and thought.
And here we don't just use plain English, but "technical" language is involved, which is specific and somewhat more difficult than ordinary everyday English.
But I only recently discovered the biggest mental differences in converting thoughts into language, a couple of years ago, when I started working with a colleague from China.
Despite AI and despite highly advanced online translators; very often I have to change the order of words in a sentence several times in order to get a meaningful message that
I want to send to my colleague from China... and vice versa.
At first, for the first couple of weeks, it was hilarious!
We didn't understand anything correct each other! We often "offended" each other fiercely! Ahahahahahaha!
It should have taken at least a month for both of us to realize that the translator was a big obstacle between us!
And then it became clear that it is a matter of mentality and how the brain works.
This is a long post, off topic, but very interesting to mention.
Maybe my posts are so long and tedious sometimes; because I realized that many will not understand the messages properly; if I don't write a small "novel" in the post,
with many details and explanations.
This is not necessary for English-speaking colleagues, they understand "Tarzan language" very easily.
But this is still an international forum, many people look at these topics and I mainly go into detail for them.
An interesting little story about languages and the way the brain works...

Hi Ivconic.

That is true. Not everything one says in English is always understood exactly as intended. Here is something that happened to me many years ago in the Philippines. I had issued a work instruction, asking that it be completed "as soon as possible." However, the Filipinos understood this somewhat differently than I had envisioned. They interpreted the instruction—"as soon as possible"—in the following way: if it wasn't "possible" for them to do it, then the work wouldn't get done "soon" either. Furthermore—regarding multiple instructions given in a single sentence, which is normal for us Germans—usually only the first instruction was carried out, while the others were ignored. It took me quite some time to grasp how others interpret "English."