TESORO GOLDEN SABRE

[tiktak]

Hi

Another method is to set the ground balance control to mid-position, and adjust the coils to achieve minimum voltage, while monitoring the output of the sample gate in the ground channel. This will automatically give you the correct phase shift between TX and RX. In this case, you only need a single-channel scope, or a meter.

Hi,
You mean pin7 lf353?

And Ivica you are rare bird but we are same blud.Smash it with the hammer!
)))
I hate those chinees too.But they are everywhere!People buy this crap for a lot of money.Strange?
And those seben are everywhere.

[Qiaozhi]

Another question for the experts:

R40 100K is mysterious to me. It connects output of comparators U106 (after diode D12) back to non-inverting input of comparator U106b (ground bal channel).

It causes clipping of the comparators output to near ground (actually near the non-inverting input which is the output of LM308 ).

I see similar thing on Amigo II circuit. What is the purpose? Why clip to LM308 output instead just ground for example?

Regards,

-SB

I think this feedback resistor provides some hysteresis for the comparator. i.e. it stops any spurious oscillations.
The diode/resistor combination forms a precision clamp circuit, to keep the output at a fixed value.

[Qiaozhi]

Hi,
that is interesting really. I expected that, cause geb channel samples at zero crossing of received signal, thus producing a minimum voltage at output of sampling gate when TX/RX phase at coil is centered on right value.

I tested that before, it works really, but had troubles with multimeter also that time... using scope I can see a distorted sinus on top of a mean value that increase/decrease when moving coil one way or another and stay at minimum voltage peak to peak at what I think is the right TX-RX phase.

In this case, also the residual phase on air is just around 200° like when measuring original coils.

Probably, I would say, this method is much more accurate cause keep track of non-linearities at oscillator and other factors that a simple "put TX/RX at 200°" will be.

That's sure not a big deal rotating the geb trimpot to compensate small inconsistencies later but that one will do using ferrite rod... having the ability of understand the "right" position where silver is still detected and ferrite almost not, and it's not so intuitive as nulling the output signal of geb sampling gate.

That's why , I think, this method is even better for those who are confused about all this stuff.

The problem is that, you compensate ferrite rod very good...and iron is not detected in disc mode (at least soft iron)... but you lose a lot of sensitivity to silver.

I found that totally nulled geb signal there means decreasing silver detection of 50% !

So, I usually retune the trimpot there to get again about full silver detection when ferrite is ALMOST nulled (means that sound at a couple of cms from overlaps)... is that right ? Who knows ?

In that position the gate output is not at zero but positive... 25-30mV.

With red bricks it works nice... but when on hot soil... red sand and the like wow ... get noise and have to reduce sens to 6 also.

This is expecially on larger coils... on 8'' or 9x8'' is not a big issue, works about good.

What do you think about ?

Kind regards,
Max

For real soil conditions the ground balance needs to be set slightly negative, somewhere between 0 and -5 degrees, but nulling the coil using the output of the ground channel sample gate is a good starting point. Then (as Max says) slightly adjust the GEB pot away from the ideal position.
George Payne has explained it quite well in this article ->
http://www.jb-ms.com/Baron/gb.htm

[Max]

Thank you (Thor) for taking time away from hammer to answer... but still confused!

I find that iron phase is greater than silver; is that different from everyone else? If it were before foil or nickel, I could use discriminator to eliminate, but it it is on other end of range -- right next to silver, only further. If I discriminate iron, everything else gone too, do you see what I mean?

Maybe I'm not careful enough turning GB pot, but... it seems if I can detect iron in All Metal mode, it comes through in Discrimination mode too! I will try harder...

Note: All Metal mode JFet gate signal is very triangular, not square. Is that correct? Maybe the problem is there. Also other JFet gate signals have rounded leading edge -- OK or not? I am like dog with a bone, not giving up...

Good experiments with Chinese MD, very interesting and entertaining, better than Harry Potter...you are the craziest I've ever seen but game aint over yet...Aziz and I taking lessons...

Cheers

-SB

Hi,
Qiaozhi is right: when coil is made right and you are around right phase between TX/RX you'll not get iron detection in disc mode, just all metal you'll detect it.

The geb trimpot is not for nulling iron: you MUST get it nulled by discriminator circuit when coil is made right.

The trimpot serves for what indicated : ground balance tuning

If you use a small ferrite rod you'll see that, when coil is made right way, you can null its effects at about middle position.

Problem is that interfere also with e.g. silver detection... so I experienced detuning a bit the trimpot to gain good silver detection again...but still ignoring almost the ferrite.

Iron is always rejected by good coil+discriminator circuit.

ALSO, NOTICE: when I wrote "IRON" I mean soft, pure iron... like in iron nails and the like... not steel alloys.

Sometimes people confuse soft iron with steel stuff... steels kinds have sometimes very different magnetic behaviour than soft iron things.
That's why you'll detect that thing.

An easy try: find a real iron nail stuff...5-7cm long you'll be sure it's just iron. Then find a 5cent (eur cent) coin.

They try to detect them in disc mode: on soft iron , if you made detector/coil good you'll get no signal at all. But you'll still detect the 5cents.

Why ? People think that 5cents are made of copper alloy... it isn't. It's just covered by that stuff, inside they are made of steel alloy core really detectable by MDs...

You can find other countries coins made of that metal alloy and all are detected easy, made actually of steel.

Kind regards,
Max

[ivconic]

Oh never mind my pc - nothing really important in it. Only dozen of trojans and few of S.Layout files...
What i suspect is that there are some buggy cameras in my workshop, behind my back!?
Yes i agree, God only knows what is phase shift at your coil Simon...???!
Make another one.
When phase shifted much out of proper angle, everything is possiblle. I had not experimented that way; to see all the possible side effects...
Usually it goes this way: ferrite,iron,thin silver,thin al foil..etc..etc.


Amtech if you want file, here it is... but seems you missunderstood me? I never traced and made copy of this nonsenced 3009..i only used its pcb shape and dimensions to draw TGSL...so if you looking for original 3009 trace...ha, i dont have it. Who need that crap anyway?

[Max]

Another method is to set the ground balance control to mid-position, and adjust the coils to achieve minimum voltage, while monitoring the output of the sample gate in the ground channel. This will automatically give you the correct phase shift between TX and RX. In this case, you only need a single-channel scope, or a meter.

Hi,
that is interesting really. I expected that, cause geb channel samples at zero crossing of received signal, thus producing a minimum voltage at output of sampling gate when TX/RX phase at coil is centered on right value.

I tested that before, it works really, but had troubles with multimeter also that time... using scope I can see a distorted sinus on top of a mean value that increase/decrease when moving coil one way or another and stay at minimum voltage peak to peak at what I think is the right TX-RX phase.

In this case, also the residual phase on air is just around 200° like when measuring original coils.

Probably, I would say, this method is much more accurate cause keep track of non-linearities at oscillator and other factors that a simple "put TX/RX at 200°" will be.

That's sure not a big deal rotating the geb trimpot to compensate small inconsistencies later but that one will do using ferrite rod... having the ability of understand the "right" position where silver is still detected and ferrite almost not, and it's not so intuitive as nulling the output signal of geb sampling gate.

That's why , I think, this method is even better for those who are confused about all this stuff.

The problem is that, you compensate ferrite rod very good...and iron is not detected in disc mode (at least soft iron)... but you lose a lot of sensitivity to silver.

I found that totally nulled geb signal there means decreasing silver detection of 50% !

So, I usually retune the trimpot there to get again about full silver detection when ferrite is ALMOST nulled (means that sound at a couple of cms from overlaps)... is that right ? Who knows ?

In that position the gate output is not at zero but positive... 25-30mV.

With red bricks it works nice... but when on hot soil... red sand and the like wow ... get noise and have to reduce sens to 6 also.

This is expecially on larger coils... on 8'' or 9x8'' is not a big issue, works about good.

What do you think about ?

Kind regards,
Max

[Qiaozhi]

Ha,ha,ha! You are spying my work??? Perhaps you installed some bugs in my workshop??? Damn!

Yes - I have installed a lot of spyware on your computer.

[Qiaozhi]

Thank you (Thor) for taking time away from hammer to answer... but still confused!

I find that iron phase is greater than silver; is that different from everyone else? If it were before foil or nickel, I could use discriminator to eliminate, but it it is on other end of range -- right next to silver, only further. If I discriminate iron, everything else gone too, do you see what I mean?

Maybe I'm not careful enough turning GB pot, but... it seems if I can detect iron in All Metal mode, it comes through in Discrimination mode too! I will try harder...

Note: All Metal mode JFet gate signal is very triangular, not square. Is that correct? Maybe the problem is there. Also other JFet gate signals have rounded leading edge -- OK or not? I am like dog with a bone, not giving up...

Good experiments with Chinese MD, very interesting and entertaining, better than Harry Potter...you are the craziest I've ever seen but game aint over yet...Aziz and I taking lessons...

Cheers

-SB

Your coil is not adjusted correctly. Unfortunately, if you've already sealed it, you will have to make another one.

[simonbaker]

"...Instead, I turn Ground Balance until iron goes away...."

Very wrong! You should turn GEB until ferrite rod goes ALMOST away - not iron. All this performed in ALL METAL mode.
Better than ferrite rod would be thing made from small pieces of rust, black sand, hot rock and very tiny and small pieces of ferrite, mixed up togather and formed in some 5x5cm shape...somebody already suggested and explained this at very first pages of this thread...search for it.
Than turn GEB untill that "thing" goes away...and at the same time switch to Disc mode (Disc pot to "1"), and try to detect small and thin silver coin. If it is detectable than leave that setup/preset that way...if not than loose GEB a bit just to start detection on thin silver and thin foil...and that is all!
Than switch back to All Metal mode and test again on ferrite mixture....If detection is appearing and it is strong than your coil is bad - make another one !

Thank you (Thor) for taking time away from hammer to answer... but still confused!

I find that iron phase is greater than silver; is that different from everyone else? If it were before foil or nickel, I could use discriminator to eliminate, but it it is on other end of range -- right next to silver, only further. If I discriminate iron, everything else gone too, do you see what I mean?

Maybe I'm not careful enough turning GB pot, but... it seems if I can detect iron in All Metal mode, it comes through in Discrimination mode too! I will try harder...

Note: All Metal mode JFet gate signal is very triangular, not square. Is that correct? Maybe the problem is there. Also other JFet gate signals have rounded leading edge -- OK or not? I am like dog with a bone, not giving up...

Good experiments with Chinese MD, very interesting and entertaining, better than Harry Potter...you are the craziest I've ever seen but game aint over yet...Aziz and I taking lessons...

Cheers

-SB

[amtech2005]

TESORO GOLDEN SABRE

Hello Ivconic , I am looking forward to the new sprint lay-out and we will see if it matches this photo ???? Thank-You..............Eugene

[ivconic]

Oh i forgot; only one error on this pcb!
Look that wrong connection at emiter resistor - should go to +8V not to ground and other from base to gnd not to +8V...
Everything else seems to be good...
Working in progress...will be ready tomorrow..

[ivconic]

It would be a shame to waste so so descent enclosure from MD3009...so i decided to use it and put another TGSL inside. Logically i had to respect original 3009 pcb dimensions and shape to suit enlosure. What a hard labour!?
So before scraped it and enjoyed with hammer, first i cleaned pcb form any component and scanned it in 1:1 so later i could import it in Sprint Layout and draw TGSL on it...Ha,ha,ha,ha!!! What a lunatic am i?
Anybody more crazy than me here? Seriously i have doubts!

[ivconic]

Pretty "pictoresque" should be my next story. I will spit on some detectors here...but hey! That's life!
So story goes on...

This summer i had chance to fully test majority of cheaper metal detectors made in China. Except Black Knight, all others could be considered as object of one and the very same experience...so;

Coils are made in pretty well cosmetic manner. Looking nice and hi pro.
Yet all coils i have been seen are .....take a deep breath....without any Faraday Cage or simillar !!!???? Ha,ha,ha!!! What a spiiiit!
This HUGE drawback showed fully on real soil. Absolutelly unstabile and therefore unuseable totally in any descent work. Who ever told you different story, you may consider him as a fraud and liar!
So....next drawback is ..."machine" itself.
For example...MD3030 and MD3009 (not 3009a version) are sharing the very same "machine" inside.
Skim look on pcb gives FALSE impression that it is actually some Fisher project, pirated by pirates from China.
Ok...maybe those really intended to make real copy of Fisher...but they failed hardly!
Why?
Simply...many things very wrongly put togather there.
I have original 1266/65 8" coil in my workshop, so logically i connected it to both MD3030 and MD3009 and tested. The hell..working exactly the same as with original coil came with those toys.
I could NOT get any benefit using original, hi profile (f.cage included) coil made by Fisher!? What the hell? So it is not only about coil? What else? Of course machine itself...
What is the main drawback? (now i come to main point).
Same MD3030 and MD3009...with original coil and with Fisher coil...still can not remain silent on FERRITE ROD...while original 1265/66 is totally silent on same rod???
So....there are some trimmers inside MD3030 and 3009.
I assumed those ignorants didnt knew how to adjust those. So i adjusted and adjusted...and adjusted...and adjusted...and few days ago even used brand new scope....and all that without success!??
It is impossiblle to make it calm on ferrite rod, no matter what you do!?
No matter which mode..no matter pots positions...no matter trimm positions...always the same - screaming loud on ferrite rod...again and again..
So 2 days ago i used 5kg hammer and smashed 3009 pcb and with a huge pleasure toosed it through window of my workshop! What a pleasure! I can not describe here!

To make this simplier....very simple conclusion;
if achived to be calm on ferrite rod...later that detector is very calm and stabille on real soil...and if not than that detector is a crap,trash and should be hammered asap!
As explained...at first i suspected mostly unshielded coils...but later turned that both (coil and detector) are totally mismatched and presents HUGE vaste of money.
Only exception is Black Knight...very stabille, very calm and with so so detection and disc. But comparing with other trash came from China...Black Knight is a real "bijou".



P.S.
Reffering remark on MD3009 and MD3009a - those are totally different. MD3009a is coming in Europe as Seben, and it is non motion...yet totall crap and totally unuseable trash. What really confused me is simillar label on pcb's although those are totally different???



This stroy i told just to picture you why ferrite rod is usefull in many cases...especially in process of nulling coils and adjusting machine.

MD3030 and MD3009 senced and loud detected every grass, stone and wet on soil, on real terrain, outdoor. I spent hours trying to make those work so so calm and stabille - without success.

Only way to make those stabille is to reduce Sense to level where it is able do detect 1cm coin bairly at 3-5cm depth!!! Ha,ha,ha,ha,ha!!!!
What a trash! What a fraud!


Oh...i can only imagine those machines to be so so succesfully used only on plain sand...on beaches or in some desert..and nowhere else.


A bit off topic here...but recently i tested also 2 branded machines; XP Gold Max (18kHz) and Cscope 2MX...
XP is so good and pleasant to work with - i dont have words!!! It is shame i can not afford to have it yet... need some money savings ...shame! Very deep, precise and accurate...real sweet machine. Justify every penny payed for it! If it was 1000e even than would be worth of those money.
Probably one of the best on market today!

Other hand Cscope 2MX is modest, middle class machine...yet very good, accurate and stabille! Bravo for Cscope! Also worth every penny involved! Probably the best compromise between price and performances today. Very simple yet very accurate, stabille and with very descent depths. Bravo Cscope! And Hurrrahh for XP !!!

As very old Cscope fan, i would like to have chance to see and test CS990 XD and CS3MX. Those models are "eaching" my imagination strongly!
I sense old Cscope spirit in those two models...although not sure yet...
Huh...damn money! Always missing!

[ivconic]

Hi Qiaozhi, Max, Ivconic - can you explain how iron discrimination works with TGSL?

In my circuit, as I turn discrimination pot, discrimination order is:

foil, nickel, penny, dime/quarter, iron.

So I can't use discrim pot to knock out iron and keep others.

Instead, I turn Ground Balance until iron goes away. But then it is gone even for All-Metal mode.

I'm confused on this. How should it work?

Thanks,

-Sb

"...Instead, I turn Ground Balance until iron goes away...."

Very wrong! You should turn GEB until ferrite rod goes ALMOST away - not iron. All this performed in ALL METAL mode.
Better than ferrite rod would be thing made from small pieces of rust, black sand, hot rock and very tiny and small pieces of ferrite, mixed up togather and formed in some 5x5cm shape...somebody already suggested and explained this at very first pages of this thread...search for it.
Than turn GEB untill that "thing" goes away...and at the same time switch to Disc mode (Disc pot to "1"), and try to detect small and thin silver coin. If it is detectable than leave that setup/preset that way...if not than loose GEB a bit just to start detection on thin silver and thin foil...and that is all!
Than switch back to All Metal mode and test again on ferrite mixture....If detection is appearing and it is strong than your coil is bad - make another one !

[ivconic]

Another method is to set the ground balance control to mid-position, and adjust the coils to achieve minimum voltage, while monitoring the output of the sample gate in the ground channel. This will automatically give you the correct phase shift between TX and RX. In this case, you only need a single-channel scope, or a meter.

Ha,ha,ha! You are spying my work??? Perhaps you installed some bugs in my workshop??? Damn!
Not "another" but ONLY ONE, as showed so far with all TGS's i done.
Most accurate method to make and adjust optimal handmade coil is just what you described Quiaozhi! Not more truth with less words! What a benefit being born British!!! I wrote novels and novels ...and you beat me with just a few words. I agree 100%!
Ok folks, humor aside....Quiaozhi just explained exact method i am using on all my TGSL's.
Except scope part. I hadn't it and hadn't chance to fully observe gates.
Now i have it and observing would be much easier and more accurate.
Very important is to set GEB to middle position, so later you will have enough reserve on both sides.
GEB trimmer actually AFFECTS phase - remember that. But..if coil is nulled badly, aint no GEB trimmer to solve that.