SBG- slow motion metal detector

[ivconic]

For the last couple of years, my place Sokobanja (formerly known as a spa in Europe) has been a favorite place for Bulgarian tourists.
Now there is no longer a border between "season" and "off season", now every weekend is "season" for tourists.
And the real season starts from about the second half of June.
However, even now, several buses with tourists from Bulgaria come to Sokobanja every weekend.
I don't even have to mail the pcb. I can ask someone to bring you the pcb and send it directly from Bulgaria!
...
I don't have recent videos, this is a video from New Year's Eve 2025, literally half of the people you see in the video are Bulgarians, tourists.
Together, everyone plays "kolo" with the locals:

[ivconic]

Yes, you are right!
"Old school"!
Many inexperienced colleagues will not understand.
The better Cscope models will be... to put it mildly "miserable" on bench and air tests, but they will always find amazing results in real soil.
I had a couple of models but my favorite is the 1220B.
...
The post office between Bulgaria and Serbia functions flawlessly. The PCB in the envelope is no problem to send.

[scs-bg]

The PCB request was a joke. I'd be happy if you were happy with the result.

[ivconic]

Ah yes!
In the meantime, you indirectly answered my question.
Just by mentioning "CScope" you explained things to me!

[ivconic]

And now one question! Ha, ha, ha!
I stopped DIY coils a long time ago!
I think I stopped when I was doing IGSL (the successor to TGSL).
Since then, I rarely build detectors, mostly for my own needs and as a hobby.
And instead of making coils; I always look to use an original coil.
Currently in my collection I have a spare new coil for Fisher 1266 and 2 coils for Fisher CZ6.
However, I see that your coils have the same number of windings, the difference is in the thickness of the wire.
Do you have specific data on resistance and inductance?
Math estimates that the TX coil is around 13-14 ohms and 0.53-0.55mH and the RX coil is around 35-36 ohms and same inductance to the TX coil.
Have you tried a detector with a different ratio?

[scs-bg]

Almost all ground balance detectors operate with a phase-shifted ground balance signal. The second channel determines the type. The detector emits a signal when the two signals match. But the constantly changing signal in both channels leads to errors. That is why a perfectly working detector in the air misses a signal in the ground that an old "C-scope" always finds. This is about real use with movement, not a test on a known buried object.

[ivconic]

When a colleague from China draws a pcb; will send me the gerber files.
Then I will order the manufacture of 5 pieces (minimum is 5) in JLPCB.
When they arrive; I can send you one or two.
This is not a problem, it is important that the detector works well.

[scs-bg]

I repair lasers and robots and I have no problem making a digital detector. I think analog detectors work better. I hope you are satisfied. I hope you can send me some Chinese boards for free. I am a poor man with only one pension...

[ivconic]

Back to the topic.
Sasho, I gave your schematic to my younger (and much smarter) colleague from China and asked him to draw me a pcb according to the given dimensions.
Until I met him a couple of years ago; I thought I was a very fast and good pcbs designer.
But then I saw that he was better and much faster. So I'll wait for him to draw it.

[ivconic]

Every amateur work is worthy of respect.
But I think someone mixed up the topics here.
We are talking about Sasho's VLF-I/B slow motion here.
PI detectors should not be confused with this thread.
Although I'm tempted to say that my Barracuda does a lot better than that PI in the video.
But let's not start such stories here, so as not to spoil this interesting topic about Sasho's detector.
There are too many topics about PI detectors on the forum anyway.


P.S.
If you want good PI insight, get ITMD3 and read it multiple times.
Carl did a phenomenal job there.
And at the end he gave a couple of very good PI projects.

[ivconic]

[scs-bg]

"The great Bulgarian inventors" are characterized by measuring whose organs are larger. I don't want to deal with that. Even in the air, this thing has no depth.

[GeoMax]

Hello Pechkata,

Is the detector board in the video you posted based on the Whites AF108 mine detector? Or what circuit is the base?

[Ruben2000]

Excellent Pechkata, that encourages me to build it. I'll have to make time for the PCB. Did you have any problems building it?

[pechkata]

The site Geotech does not allow sending files to the Internet. The PCB is different from the one that works well, many elements are added. This is a complex structure and it would be difficult to foresee everything. I don't want to deal with this, in video see how well it works. Anyone who has a desire can develop PCB himself. He remains satisfied. Many people think that "pulse induction" is some kind of magic but it is not so. The detector finds many things after very expensive factories detectors.

Pulse induction is magic.