TESORO GOLDEN SABRE

[ivconic]

Look at this one Geo:

http://www.soko-banja.org/

Regards!

[ivconic]

No! Look this one with English translations:

http://www.sokobanja.org.yu/

[ivconic]

Don't believe this test' 7'' for clasicI........ 8'' for XLT, GTI 2500 and 1236???? and 9" for 1266 and X2 and X5 and ........
14'' for Explorer SE (maybe the best detector) and only the half???? for the XLT and GTI2500 (for me are similar with Explorer SE)
I believe that the writer has a sympathy to Minelab

I can agree on this with Geo. From that list i have luck and oportunity to test over 60% of those machines...Not exactly results...I tell you...
Although i can accept differences due type of soils on which test were performed...Might be that test accurate for that type of soil??? Who knows?

[Qiaozhi]

I can agree on this with Geo. From that list i have luck and oportunity to test over 60% of those machines...Not exactly results...I tell you...
Although i can accept differences due type of soils on which test were performed...Might be that test accurate for that type of soil??? Who knows?

The tests were done on UK soil. According to the preamble, it appears that any large iron objects were removed, but small nails, etc., were left in the soil. I suspect the test bed was therefore fairly iron-infested, which is not a good place for testing. However, it surprises me that the Tesoros did not fair well in the test, and these are renowned for their ability to pick out small items amongst the trash. Personally this looks like Minelabs bias at work here. Like all subjective tests it may be unintentional, but who knows? Also, this is very strange, because they are a C-Scope agent.

[Max]

The tests were done on UK soil. According to the preamble, it appears that any large iron objects were removed, but small nails, etc., were left in the soil. I suspect the test bed was therefore fairly iron-infested, which is not a good place for testing. However, it surprises me that the Tesoros did not fair well in the test, and these are renowned for their ability to pick out small items amongst the trash. Personally this looks like Minelabs bias at work here. Like all subjective tests it may be unintentional, but who knows? Also, this is very strange, because they are a C-Scope agent.

Hi,
I agree... infested iron soil is not ideal for comparing machines. I think that a clean from iron (totally), medium soil is the best scenario for comparing detectors.

Of course there are some that can deal with trashy sites better than others... but iron is always a problem for any detector and cause conditions can change so radically from site to site... it's better to me having comparision on a clean test-garden.

Then after... some trashy addicted machine could be tested in trashy sites to get a picture of their ability of ignoring iron but still giving useful signals.

I will restrict that last test just for machine claimed of doing that, like some Tesoro's and others claimed trashy addicted MD (e.g. RedHeat).

For example... have not much sense to me a test like above (trashy site) using e.g. a PI detector. It's so easy picking up iron that way that even an essential VLF with no geb could beat the PI in this trash ignoring. Have no meaning for me comparing so different things in that bad/extreme conditions.

Best regards,
Max

[Max]

To Ivconic and Max.
I believe that the best way to Null the coils is a oscilloscope . The dummy load must be a resistor and a capacitor parallel with the coil and a resistor in series with coil so the capacitance of the scope probe to don't influence the total capacitance. This is the way that i null my coils
Regards
Btw.. Ivica from who city are you??? Maybe the next month my son to come to Servia for a "Tae Kvodo " fight, i dont know yet the city.....

Hi,
yes I agree. Seems the right way.

Kind regards,
Max

[Max]

mixed silver stuff ?

Hi,
few days ago I've tested my TGS with various coins...on air...and get good results with pure silver but a bit less with alloys.

I've tested with a 30mm diameter 925/1000 silver coin and got 39cm on air... then with another 30mm diameter but 825/1000 silver coin I got much less :
just 34cm on air.

The second coin has probably 165/1000 of copper and I think that influenced much reading about it.

Phase shift due to different metals seems mix in a way that make detection less easy !

I've seen before on other machines similar behaviour... very often with 50% silver coins.

34cm is not too bad for a 30mm coin...but also not a big distance: I'd like to know what do you think about... if you have similar problems e.g. when coinshooting in parks etc

Any comment welcome.

Kind regards,
Max

[ivconic]

Alternative approach

So, i tried to setup alternative "zero" with this way of nulling coil. Why? TGS already have sufficient GEB&DISC adjustments...
Dirung working with TGSL under real conditions i noticed situatin on SOME fields TGSL cant be grounded well; it still can produce fast chatters ocassionally...similar with almost all other detectors.Even GT (which is very stabile) sometimes can jitter a bit. Despite all my love for TGSL i still have to say that its GEB is not perfect. When testing in workshop it can absolutely reject ferrite,iron and simillar....even that famous mineralized clay. But outdoor i noticed some jitters from time to time. To repeat; when handling with cable i cant provoke any falses, also touching coil - still no falses, very calm and stabile. But swinging arround few inches over soil surface, sometimes it can bleep??? I still havent find out what should be the reason of that? Several different coils were checked, so i simply can not blame coils for that...Adjusting GEB trimmer slitely mm per mm wont solve problem.Actually GEB trimmer is more likely to affect discrimination than GEB? If rised more you can easilly lose some coloured metals like nickel coins or small silver...GEB trimmer is adjusted at the very point where is just about to lose nickel....
So i was thinking somehow to extend that part of scale. But how?
So i left device aside and tried with coil.That's why nulled latest coil in a bit more "positive" manner...Is it good? I dont know yet. I'll see when rain stops .
I want to ask you is there any other way to extend GEB adjustments on TGS?
Putting multi turn trimm wont solve the problem..

[ivconic]

Hi,
few days ago I've tested my TGS with various coins...on air...and get good results with pure silver but a bit less with alloys.

I've tested with a 30mm diameter 925/1000 silver coin and got 39cm on air... then with another 30mm diameter but 825/1000 silver coin I got much less :
just 34cm on air.

The second coin has probably 165/1000 of copper and I think that influenced much reading about it.

Phase shift due to different metals seems mix in a way that make detection less easy !

I've seen before on other machines similar behaviour... very often with 50% silver coins.

34cm is not too bad for a 30mm coin...but also not a big distance: I'd like to know what do you think about... if you have similar problems e.g. when coinshooting in parks etc

Any comment welcome.

Kind regards,
Max

Yes Max, same with my devices! See my previous post. It has something to do with GEB&DISC part. Something is to "narrow" there? What?
Try to play a bit more with GEB trimmer - you will see huge differences...

[ivconic]

?

How about this substitution for RX coil?
Any benefits,drawbacks...?
What do you think?

[Max]

So, i tried to setup alternative "zero" with this way of nulling coil. Why? TGS already have sufficient GEB&DISC adjustments...
Dirung working with TGSL under real conditions i noticed situatin on SOME fields TGSL cant be grounded well; it still can produce fast chatters ocassionally...similar with almost all other detectors.Even GT (which is very stabile) sometimes can jitter a bit. Despite all my love for TGSL i still have to say that its GEB is not perfect. When testing in workshop it can absolutely reject ferrite,iron and simillar....even that famous mineralized clay. But outdoor i noticed some jitters from time to time. To repeat; when handling with cable i cant provoke any falses, also touching coil - still no falses, very calm and stabile. But swinging arround few inches over soil surface, sometimes it can bleep??? I still havent find out what should be the reason of that? Several different coils were checked, so i simply can not blame coils for that...Adjusting GEB trimmer slitely mm per mm wont solve problem.Actually GEB trimmer is more likely to affect discrimination than GEB? If rised more you can easilly lose some coloured metals like nickel coins or small silver...GEB trimmer is adjusted at the very point where is just about to lose nickel....
So i was thinking somehow to extend that part of scale. But how?
So i left device aside and tried with coil.That's why nulled latest coil in a bit more "positive" manner...Is it good? I dont know yet. I'll see when rain stops .
I want to ask you is there any other way to extend GEB adjustments on TGS?
Putting multi turn trimm wont solve the problem..

Hi Ivconic,
as always you give us good informations and ideas about how to approach problems.
I've tested behaviour on 5 different soils at the moment and find that 2 gave me problems with fixed geb setup: the trimmer position I've adjusted on middle soil gave me bad working on 1 soil made of a mix of sand (or similar to sand) and clay... all right - iron salts and oxides are present there. Erratic bursts of noise when e.g. a small ammount of soil (not perfectly plain) give such an height gradient (like a small "hill") respect to the sorrounding part of soil.

In plain area the same effect occours at random... and I don't know cause but think there is something in the underground layers structure that point detector on the same way or hot rocks, result is the same: noise.

In another soil I get some rare bleeping similar: soil is made mainly of clay this time.

Other 3 test sites showed perfect performances and nice depths with NO BLEEPING AT ALL. Soils are different and made of mix of clay and "sand"...one has hi organic compounds presence on first 10-15cm.

Is that GEB that need adjusting ? I think so.

I've made bandidoII and it has an extended disc mode and multiturn GEB pot that make it possible find the exact spot where GEB is perfect (but not so easy to find). I think that TGS would benefit too of a multiturn GEB pot... but I agree also with you on DISC effect of geb trimmer (really easy to see): all right... multiturn pot won't solve our problem totally.

Center tap to GND ? I don't know if could solve it, but it's an idea... if noise, as seems, is related to ferromagnetic gradients probably their amplitude influence would be cancelled out by this config respect to GND...

I think that it's a forced diff. configuration for the two halves... thus giving cancel of signal due to noise... but also to targets... : that way will be more stable but I'm scared we'll lose some depth.

Only way to know is it could solve or reduce problem is try it.

Kind regards,
Max

[Max]

Hi,
watching again it I start thinking at fact that LF353 diff config would amplify differential signal from the external leads ...so the sum of the two halves of RX... and that the effect respect GND is totally differential... so no noise or signal respect to GND at rx external leads...cause of the center tap.

An advantage could be related to shield to coil capacitive effects during transients... that configuration will null the effect due to the fact the shield will always see same voltage for the 2 rx external leads , also with huge differences respect to the real voltage potential between the two: this will improve SNR if transients generate falsing due to capacitive effect inside the housing... due e.g. to the previous config (one lead at GND and the other "floating") that seems a realistic perspective for an MD coil.

That means, if noise is related to e.g. capacitive histeresys of dielectric between coil and shield, we'll get a more stable design that way.

Ideally that will improve SNR but considering the splitting of RX in two sections we'll have to consider also the mutual inductance effects between the two-> we'll have an air core transformer at RX and that will add inertia to the RX side cause of magnetic mutual energy interactions of the two halves.

That's a secondary effect but could have its importance in whole MD performances... expecially for deep and small targets.

What do you think ?

Best regards,
Max

[Qiaozhi]

So, i tried to setup alternative "zero" with this way of nulling coil. Why? TGS already have sufficient GEB&DISC adjustments...
Dirung working with TGSL under real conditions i noticed situatin on SOME fields TGSL cant be grounded well; it still can produce fast chatters ocassionally...similar with almost all other detectors.Even GT (which is very stabile) sometimes can jitter a bit. Despite all my love for TGSL i still have to say that its GEB is not perfect. When testing in workshop it can absolutely reject ferrite,iron and simillar....even that famous mineralized clay. But outdoor i noticed some jitters from time to time. To repeat; when handling with cable i cant provoke any falses, also touching coil - still no falses, very calm and stabile. But swinging arround few inches over soil surface, sometimes it can bleep??? I still havent find out what should be the reason of that? Several different coils were checked, so i simply can not blame coils for that...Adjusting GEB trimmer slitely mm per mm wont solve problem.Actually GEB trimmer is more likely to affect discrimination than GEB? If rised more you can easilly lose some coloured metals like nickel coins or small silver...GEB trimmer is adjusted at the very point where is just about to lose nickel....
So i was thinking somehow to extend that part of scale. But how?
So i left device aside and tried with coil.That's why nulled latest coil in a bit more "positive" manner...Is it good? I dont know yet. I'll see when rain stops .
I want to ask you is there any other way to extend GEB adjustments on TGS?
Putting multi turn trimm wont solve the problem..

The ground balance works by sampling the received signal at the zero-crossing point. The theory is that both ferrous and non-ferrous targets affect the amplitude and the phase of the received signal, whereas neutral soil will only cause a decrease in magnitude. There is no phase-shift. Since you are sampling at the zero-crossing, the GEB channel cannot detect a change in the amplitude of the signal unless there is also a phase-shift. Ferrite causes a similar response, and that's why it's often used to find the correct GEB setting. Unfortunately ferrite does not react exactly like real soil, and the offset can be as much as -5 degrees. If you're using a preset GEB, then you will need to adjust it off from the ideal position by a few degrees and set the threshold to silent search, but the best solution is to have an external GEB control. If you set the GEB control to any position other than sampling at the zero-crossing point, then it's not acting as a ground balance control.

[JC1]

more information

Hi All,

George Payne on fixed (preset) vs adjustable GB
and coil design.

http://jb-ms.com/Baron/gb.htm

A good read for any who have not seen it.

[ivconic]

"..That's a secondary effect but could have its importance in whole MD performances... expecially for deep and small targets.

What do you think ?.."

Dont know yet.
Worth of trying. I'll try that and later inform here...Might be that some extra changes needed arround front end...i'll see.