Calibrating MD3010 correctly

[kt315]

Для удобства настроек на грунте решил вынести подстроечники с платы на корпус. Будет не так надежно, зато появится возможность подстроиться на ходу.
На плате 2 группы подстроечных резисторов:
1) R3 и R4 100кОм - отвечают за пинпойт.
2) R1 и R2 по 20кОм отвечают за частоту и дискриминацию. Рекомендаций по использованию пока нет. надеюсь здесь я буду первым.
Переменные резисторы закрепил на корпусе с помощью клеевого пистолета, в будущем необходимо под них выполнить резиновые прокладки во-избежание случайного проскальзывания.

https://www.youtube.com/watch?v=iBr89txjLs4

For the convenience of the settings on the ground, I decided to remove the trimmers from the board to the case. It will not be so reliable, but it will be possible to adjust on the go.
There are 2 groups of trimmers on the board:
1) R3 and R4 100kOhm - are responsible for the pinpoint.
2) R1 and R2 at 20kOhm are responsible for frequency and discrimination. No recommendations for use yet. I hope here I will be the first.
The variable resistors were fixed to the case with a glue gun, in the future it is necessary to make rubber gaskets under them in order to avoid accidental slipping.

[kt315]

Interesting that the coil has the TX on the inner winding, and the RX / Bucking coils on the large outer winding.
I guess the little loop on the TX with a solder joint is where the number of turns has been fine-tuned by joining a single turn extra in series.

i guess all standart but RX bucking coil done inside of TX. some russians do that way.

[dbanner]

Interesting that the coil has the TX on the inner winding, and the RX / Bucking coils on the large outer winding.
I guess the little loop on the TX with a solder joint is where the number of turns has been fine-tuned by joining a single turn extra in series.

That coil looks a mess. L2 is hilarious. I don't think these guys were working with an optimal coil design. It would be interesting to see if a more conventional coil topology (a DD type search loop, for example) would solve some of the issues with the slow response and discrimination problems. I find it very strange that nobody has tried to replace the coil as a first step to try to solve the issues with this detector. That would be my first plan- try a standard DD coil.

The circuit on the pcb looks to be quite sophisticated for just a toy. Yes it has the performance of a toy, but the circuit may be quite good.
The problem might be in the stupid coil.

[kt315]

that nobody has tried to replace the coil as a first step to try to solve the issues with this detector.
----
why? i had give a link on youtube. this guy did replaced coil. only you run ahead before i do following translation.

[dbanner]

that nobody has tried to replace the coil as a first step to try to solve the issues with this detector.
----
why? i had give a link on youtube. this guy did replaced coil. only you run ahead before i do following translation.

Sorry, I don't see him replacing the coil with a DD

Can you show me where he tries a different coil?

I see him tinkering the existing coil for better performance.

I can't understand what he is saying, so I'm not sure of what he was up to.

[dbanner]

2) R1 and R2 at 20kOhm are responsible for frequency and discrimination. No recommendations for use yet. I hope here I will be the first.
The variable resistors were fixed to the case with a glue gun, in the future it is necessary to make rubber gaskets under them in order to avoid accidental slipping.

Are you kidding me? You see he opened the coil and then he resealed it, but he didn't do frequency analysis and discrimination tests with oscilloscope, while probing the circuit? Only tinkered with the pinpoint sensitivity trimmer? What a waste of time.

Frequency and discrimination would be among the first things I'd be checking out.

SHOW ME WHERE HE REPLACED THE COIL WITH A DD COIL. I would like to see for myself.

[kt315]

why you are so impatient DB??? there are FOUR parts! and every part shows stage of the improvement -!!!
PART 1 https://www.youtube.com/watch?v=nGLef53jn14

Refinement of the MD3010ii metal detector.
Part 1. Opening the coil, balancing the alternator on the coil and on the board. The result - a scent - 25-27cm for the Soviet 5 kopecks. You can?t achieve more without an oscilloscope on this coil.

Dear friends and guests of the channel, if you liked the video, but you do not understand Russian, then just write me in the comments. And I will, as far as possible, make subtitles in English or Spanish)

Estimados amigos y clientes del canal, si le gusta el video, pero no entienden la lengua rusa, simplemente me escriben en los comentarios. Y voy a hacer todo lo posible subt?tulos en Ingl?s o Espa?ol)

[dbanner]

First, you must determine the Tx operating frequency, and the Tx coil inductance/resistance on the stock coil.
Then determine the Rx tuned resonance(if any), and the Rx inductance/resistance.

If possible you must scope the Tx and Rx at its quiescent state (no target), to see what you see.

Based on this information and data collected, together with reverse engineer of the scheme of the front end, you can determine if the stock coil is doing its job properly or not, and if the front end of this detector is a feasable circuit.

You can build a DD coil to fit the front end of this detector for better performance if you think that is possible.

Seeing a bundle of wire (L2) just flapping in the breeze on the stock coil, with Rx and Bucking coil on the outside and Tx on the inside, gives me pause.
I think the response can be made a lot sharper with a DD coil or a standard concentric. But who knows??, maybe I'll get one just to tinker with for the christmas blues. It may just push me over the top!!!!

[kt315]

schematic and coil are similar to ace-250. files archived.

[kt315]

sch https://d.radikal.ru/d00/1902/5f/e79f422826fb.gif

[Skippy]

DB: You would be more rewarded if you purchased a GC-1023 and reverse-engineered it. At least it appears to be a functional machine, with the interesting feature of tone-break audio.

[kt315]

GS-1023 is fully analog sch. i do not see a micro on its pcb.

[kt315]

crosslinked to threads

https://www.geotech1.com/forums/show...-Ace-300/page2
https://www.geotech1.com/forums/show...-ACE-250-clone

[dbanner]

DB: You would be more rewarded if you purchased a GC-1023 and reverse-engineered it. At least it appears to be a functional machine, with the interesting feature of tone-break audio.

Oh, I tried but nobody help me. I draw complete PCB of GC-1023, with all componenets. Only missing few top side track I could not resolve from the photographs.

[dbanner]

If the problem with the MD-3010ii is with the software, then there is nothing really that can be done about that.
Perhaps the micro can be cut out of the circuit altogether, and make the thing totally analog.
I still maintain that the pcb looks pretty complex for such a poorly performing circuit.