TESORO GOLDEN SABRE

[Qiaozhi]

Very correct,so as i noticed during last months. Whenever i tried to make "perfect" ballanced coil and close to resonant, always ended up with severe problems!
Simply Tesoro is not device designed to work that way.
I am not sure, but for real do have feeling that some "standing" current occurs randomly in cable!? Why,how....damn i dont have answers yet.
Other question is bugging me for longer period;
is there any way to filter "traffic" between coil and device? Some kind of rf choke to be applied?
I was thinking to couple somehow TX and RX in coil.
Still i dont understand well those reistors usually put in Garrett coils.Coupling TX and RX. 560k or 390k in some cases i met 2M2...?
Also i was thinking to put ferrite ring somewhere on cable! Wild idea!?
There is no way for me to provoke intentionally those "standing" currents in my workshop where i can use some instruments to measure and see what is all about. Those occuring randomly and always unexpectable!
I will repeat, i experienced exact the same with Classic III which is quite different than TGSl so this teels me that problem is general, not tied especially to Tesoro.
Once, but only once i experienced the same even with Minelab Misketeer on some terrain.
But with this TGSL latelly this happening pretty often.
I havent founded any simillar explanation in much of the asticles and patents i saw so far. Usually those are mentioned generally, not explained well.
My coils are well joined and stiff. I am using joint filler with high density and fast drying without relative movements while drying, so called "cold" drying.
Later coils are very hard and stiff like a stone.
Exact mass as used in comercial coils made for Minelab or Fisher or Garret latelly. I do check ballance before and after applying mass.
This will need more to work on. I cant live with problem, without knowing and understanding it well.
Regards!

Ahhh! ... the other problem could be that the tuning caps are not in the search head, but are in the main housing. In this case, the cable capacitance is also part of the coil tuning, and you must use very high quality connecting cable.

[ivconic]

Hi ivconic

you must be fully grounded during metal detecting, mean no isolative shoes, nor other plastic wears.

regards
M6

Thanks!
Today i went on same field, where i had problems other day. But this time with new coil and new (different) cable. I worked 4 hours without falses at all.
I guess problem is somehow solved. This time i used cable (explained above) made from 2 coaxials taken from SVGA to PC cable. That cable consisted of 3x coaxials and 3-4 singles, as well as shield and one single steel wire. So i cut it and pulled out only 2 coaxials. Put those in plastic coat and used it to connect coil to detector. So today i intentionally went to same field to see differences. Is it because different temp. conditions or just cose of cable, yet today i spend 4 hours quietly and piecefully!
No falses no erratic behavior.
This might be tricky! Might be that problem still exist only didnt happened due different weather conditions? Who knows? Only time will tell.
BTW i founded one silver coin and few items.

It is not the cable

Hi ivconic

you must be fully grounded during metal detecting, mean no isolative shoes, nor other plastic wears.

regards
M6

[ivconic]

Very correct,so as i noticed during last months. Whenever i tried to make "perfect" ballanced coil and close to resonant, always ended up with severe problems!
Simply Tesoro is not device designed to work that way.
I am not sure, but for real do have feeling that some "standing" current occurs randomly in cable!? Why,how....damn i dont have answers yet.
Other question is bugging me for longer period;
is there any way to filter "traffic" between coil and device? Some kind of rf choke to be applied?
I was thinking to couple somehow TX and RX in coil.
Still i dont understand well those reistors usually put in Garrett coils.Coupling TX and RX. 560k or 390k in some cases i met 2M2...?
Also i was thinking to put ferrite ring somewhere on cable! Wild idea!?
There is no way for me to provoke intentionally those "standing" currents in my workshop where i can use some instruments to measure and see what is all about. Those occuring randomly and always unexpectable!
I will repeat, i experienced exact the same with Classic III which is quite different than TGSl so this teels me that problem is general, not tied especially to Tesoro.
Once, but only once i experienced the same even with Minelab Misketeer on some terrain.
But with this TGSL latelly this happening pretty often.
I havent founded any simillar explanation in much of the asticles and patents i saw so far. Usually those are mentioned generally, not explained well.
My coils are well joined and stiff. I am using joint filler with high density and fast drying without relative movements while drying, so called "cold" drying.
Later coils are very hard and stiff like a stone.
Exact mass as used in comercial coils made for Minelab or Fisher or Garret latelly. I do check ballance before and after applying mass.
This will need more to work on. I cant live with problem, without knowing and understanding it well.
Regards!

[Qiaozhi]

Uh one more thing. So far i made coils in manner to TX and RX windings number were close. Ex. 102 and 108, 120 and 118 etc.etc.
I think this leads to risk to push those to be almost resonant. Today i made coil with noticeable difference in number of windigs, 107 and 98. Although now i am thinking, i could done even more different. Damn!
To make greater difference in coils.
I even think now to make 130 for RX and 110 or 105 for TX.
That's why i would like to hear Quiaozhi's opinion on this. He experimented more with resonant coils than me.
Hey Quiaozhi! Give me some lead here! What possibly could go wrong with this? Except facts Max mentioned already.
About Nexus....it is using fully resonant coils. How it was done there? How to prevent selfocillations if coils tends to be resonant?
But than again i had same case with Classic III and coil which was far away to be resonant...???? I am on begining again!?

Actually it is Georgi that has all the knowledge on making really good fully resonant coils. The reason for using resonance is to dramatically increase the sensitivity of the detector, but you also need to construct these coils very carefully. They must be mechanically stable, otherwise the detector will become unusable. This might be why you are thinking that self-oscillation is occuring. However, in the case of the TGLS and other Tesoro designs, using resonant coils will severely affect the phase relationship between the TX and RX coils, and the ground balance and discrimination circuits will cease to function properly. These detectors work best with the RX coil tuned slightly higher than the transmit frequency. You can adjust the phase relationship somewhat by changing the position of the coils, but then you increase the residual TX voltage generated at the receiver.
Making resonant coils that work well is extremely tricky, and that's why major detector manufacturers don't do it.

[ivconic]

Uh one more thing. So far i made coils in manner to TX and RX windings number were close. Ex. 102 and 108, 120 and 118 etc.etc.
I think this leads to risk to push those to be almost resonant. Today i made coil with noticeable difference in number of windigs, 107 and 98. Although now i am thinking, i could done even more different. Damn!
To make greater difference in coils.
I even think now to make 130 for RX and 110 or 105 for TX.
That's why i would like to hear Quiaozhi's opinion on this. He experimented more with resonant coils than me.
Hey Quiaozhi! Give me some lead here! What possibly could go wrong with this? Except facts Max mentioned already.
About Nexus....it is using fully resonant coils. How it was done there? How to prevent selfocillations if coils tends to be resonant?
But than again i had same case with Classic III and coil which was far away to be resonant...???? I am on begining again!?

[ivconic]

"..The erratic behaviour happens in some particular conditions I think... "

Yes. I was pretty confused yesterday, cose last few fields device worked very calm for hours. It was constantly cold than. But yesterday it was cold in the morning and as sun rised more and more hot.
Today i finished another 27cm coil. But this time i changed to another cable. Since i couldnt obtain original i made my own; i took SVGA cable from old monitor and cut it and pulled out 2 fat,good shielded and coated with plastic cables. Those 2 later i put in another plastic coat and used it as cable for search head. So now i have 2 separate shielded coaxial cables put in one common coat. Coil is finished and now is drying. Will wait until tomorrow to take it out and test. If it was about previous cable, than problem is solved. If not than only one possibility left; small TGSL pcb. Must be something critically close on it? But what? Friends from Netherland done really great job and made excellent pcb. I checked components placements many times. Aint no 2 "critical" components close to each other.
Fets....yes those could be source of problem. If that turns than i will mod this and replace those with cd4016 or simillar.
Actually we have Bandido here done that way!? Right?
I will wait until tomorrow.
Regards!

[Max]

I DONT SOLVE MY PROBLEMS WITH TGS. WHEN THE COILS ARE PERFECT NULLED THE SENS GO AT MAX AND PRODUCE A SELFOSCILATION.

I WAS THINKING IN R.O.E. (ESTATIONARY WAVES) LIKE RADIOAMATEURS ANTENNAS WERE THE LENGHT OF CABLE IS VERY IMPORTANT.

REGARDS

DIRCEU

Hi,m
self oscillations are great part related to comparators there...

do you use 1Mohm resistor mod there ?

If so... and you have often instability so selfoscillations... disconnect it and leave as original.

This mod of 1Mohm is good on already stabilized/stable MDs... not if there's already instability.

Kind regards,
Max

[Max]

Additionally i was wandering about cable lenght here?
Is it matter what lenght must be use in coil cables?
I noticed extremly long cables at Minelab coils. At Musketeer and Sovereign search heads, cables are so long that i could make my usuall 2 cables from one of those!??!
Are they put such long cables just to allow user to attach device on belt or there is another reason for that.
Aint no chance for me to obtain such high quality cable as Minelab's. But i used various cables so far on various handmades. This is first time (on TGSL) that i am having this problem almost constantly!?
Usually i do cut cable at 1-1.2 meters and it showed as enough for one search head. Even sufficient. But Minelab's cables are (havent measured but presuming) arround 2 meters and possibly more!!!!
I still do remember my nerving when assembling Musketeer or Sovereign on field preparing to start coinshooting. I had to wound and wound and wound cable arround bar so long - due its lenght!!!
But those Minelabs were rock stabille due propsecting - neither one false in months!
How can i predict cable behaviour? How to prevent this problem by calculating lenght of cable?
Cable i am using lately is not highest possible quality but for sure is not lowest either.
So i am really stuck in this problem seriously...need some help.

Hi,
yes, happened also to me... sometimes. I use often 1.20 meters screened cable... not more... cause I know that the cable the more problems there. Used longer cables on other kind of stuff never on TGS or TGSL. Also... about TGSL that I've realized... but not completely tested till now I have also more instability... and I think is related to different PCB and components disposition on TGSL.

TGS exposed wild behaviour in paste cause of other problems but cable appears at source of them , from time to time, when on field.

I also wound it spiral on the pole and leave always last 20-25 to coil straight, using some pastic fixing, same kind used to keep wires tight together in complex wirings. I usually made first fixing at 20-25cm from search head and then other 2 , one at middle and one near connector and control box.

Is better keeping cable well fixed on pole and prevent movements there.

The erratic behaviour happens in some particular conditions I think... but cannot understand till now what to look for in circuit. If cable is well fixed I think problem is not from it.

I noticed that device warm-up is around 4-5 minutes for good operations and then it goes really good (at least my first TGS assembled with pole and everything) apart spot randomic that happens after 20-30 minutes BUT NOT ALWAYS... sometimes it's rock solid for 2 hours also.

I think real problem is heat/cold climate : there are parts that , after warm-up, react very bad at large temperature transients. I noticed that if climate is cold (like early in the morning) and then Sun become stronger and stronger the increase warm-up of device could lead to instability.

I think the problem could be located at fet sampler stages as 1st , and at comparator as 2nd factor.

The fets are really unstable devices to me... and commutation characteristic change (like e.g. RDSon) a lot even if temperature change just of some 0.5-0.8 °C inside the control box. So large (many) degrees variations can lead instability cause of disturbed simmetry of samplers action.

When I say "change a lot" I mean... change is relatively few thing... but we have so hi amplification and edge conditions that any little asimmetry will result in unbalance and erratic behaviour. And comparators the same story... not perfect simmetry and any channel signal asymmetry will be a problem at comparators on TGS.

An easy way to test for fet instability is heating up them with fingertip or a low power soldering iron (e.g. 20W, without touching them but just heating up air near them at few mm distance).

Best regards,
Max

[DIRCEU]

Additionally i was wandering about cable lenght here?
Is it matter what lenght must be use in coil cables?
I noticed extremly long cables at Minelab coils. At Musketeer and Sovereign search heads, cables are so long that i could make my usuall 2 cables from one of those!??!
Are they put such long cables just to allow user to attach device on belt or there is another reason for that.
Aint no chance for me to obtain such high quality cable as Minelab's. But i used various cables so far on various handmades. This is first time (on TGSL) that i am having this problem almost constantly!?
Usually i do cut cable at 1-1.2 meters and it showed as enough for one search head. Even sufficient. But Minelab's cables are (havent measured but presuming) arround 2 meters and possibly more!!!!
I still do remember my nerving when assembling Musketeer or Sovereign on field preparing to start coinshooting. I had to wound and wound and wound cable arround bar so long - due its lenght!!!
But those Minelabs were rock stabille due propsecting - neither one false in months!
How can i predict cable behaviour? How to prevent this problem by calculating lenght of cable?
Cable i am using lately is not highest possible quality but for sure is not lowest either.
So i am really stuck in this problem seriously...need some help.

I DONT SOLVE MY PROBLEMS WITH TGS. WHEN THE COILS ARE PERFECT NULLED THE SENS GO AT MAX AND PRODUCE A SELFOSCILATION.

I WAS THINKING IN R.O.E. (ESTATIONARY WAVES) LIKE RADIOAMATEURS ANTENNAS WERE THE LENGHT OF CABLE IS VERY IMPORTANT.

REGARDS

DIRCEU

[ivconic]

Additionally i was wandering about cable lenght here?
Is it matter what lenght must be use in coil cables?
I noticed extremly long cables at Minelab coils. At Musketeer and Sovereign search heads, cables are so long that i could make my usuall 2 cables from one of those!??!
Are they put such long cables just to allow user to attach device on belt or there is another reason for that.
Aint no chance for me to obtain such high quality cable as Minelab's. But i used various cables so far on various handmades. This is first time (on TGSL) that i am having this problem almost constantly!?
Usually i do cut cable at 1-1.2 meters and it showed as enough for one search head. Even sufficient. But Minelab's cables are (havent measured but presuming) arround 2 meters and possibly more!!!!
I still do remember my nerving when assembling Musketeer or Sovereign on field preparing to start coinshooting. I had to wound and wound and wound cable arround bar so long - due its lenght!!!
But those Minelabs were rock stabille due propsecting - neither one false in months!
How can i predict cable behaviour? How to prevent this problem by calculating lenght of cable?
Cable i am using lately is not highest possible quality but for sure is not lowest either.
So i am really stuck in this problem seriously...need some help.

[ivconic]

I am back from several days of field experiments.
Max and others i have few questions here,maybe you can help;
I noticed strange behavior at my last 3-4 TGSL's???
On the field, when turned ON, those works perfectly stabille for 10-20 miutes.
Than suddenly device got pretty crazy!? Producing loud chatters and falses randomly. I tried so hard to locate source of problem. After a while, when turned OFF and ON again it is continue to work good and calm for a while.
And it is repeating this behavior randomly during all day on the field. Same was with another coil. And another. Same was when i chnged another TGSL device.
After hours of trying to locate problem, somehow i founded possible source; cable from coil to device???
I am using same cable in last 10 devices. It is shielded cable with 3 separate leads. Shiled and one lead for TX and other 2 leads for RX. RX is connected to gnd in search head on previously described way.
Cable is usually wounded in spiral arround bar.
So finally i discovered when device goes crazy i take spiral cable and moving it a bit up or down - sliding it on bar. In most of cases wild behavior disappears. In most of cases but not in all cases?
Sometimes i punch device box hard and falses disappear, sometimes dont.
I turned all possible pots and switches wildly during falses to spot if there is any possible break in cicruitry - but not.
So finally only moving spiral of cable up or down on bar can realtivlly solve the problem.
So i am thinking some intereferences occuring in cable spiral randomly.
Is it possible?
This is occuring only in TGSL version. I havent noticed simillar with TGS made on large pcb so far. Oh yes, once but it was short lasting problem.
Same behavior i had in the past with my Classic III handmades. Those usually worked very good but ocassionally perfomed same problematic falsing and chattering.
So...i am a bit confused? Is it cose of cable? I must change cable for good. Must find some other type o cable.
Can you tell here exactly what cable you are using?
Can you make photo or sketch.
This is long lasting problem i noticed from the first device i made. But in the past it was rare. Now at last several devices this problem is occuring frequently.
Actually in that moment it is irelevant if i lift coil away from soil or lower it down. Falses and chatters are constant. I tried to fix it with GEB knob, but it doesnt influencing this behavior at all.
So i imagine this as sudden appears of some static currents in cable. Those "staying" currents are there and resident until i do something randomly and than "disharge" those currents somehow.
I was thinking somehow to change something crucial in design to avoid this in future. But what? I was thinking to relocate RX cap 15nF from pcb to search head or ...??? I really dont have a clue. Once i tested with cap in coil and sensitivity was much less. Detection was poor.
Only one thing here interesting me much; is it possible that cable could "suck" up some interferences or other possibilty - cable to "load" some static currents in short time and it will distort RX permanently until i do something to "disharge" that load. By twisting and moving cable spiral up or down sliding on the bar or something simillar???
Very hard to locate problem itself. Once i locate it, it will be piece of cake to solve it. Damn!
Everybody here ...help!
Hey Carl,Sean....what do you think on this?

[ivconic]

I am back from several days of field experiments.
Max and others i have few questions here,maybe you can help;
I noticed strange behavior at my last 3-4 TGSL's???
On the field, when turned ON, those works perfectly stabille for 10-20 miutes.
Than suddenly device got pretty crazy!? Producing loud chatters and falses randomly. I tried so hard to locate source of problem. After a while, when turned OFF and ON again it is continue to work good and calm for a while.
And it is repeating this behavior randomly during all day on the field. Same was with another coil. And another. Same was when i chnged another TGSL device.
After hours of trying to locate problem, somehow i founded possible source; cable from coil to device???
I am using same cable in last 10 devices. It is shielded cable with 3 separate leads. Shiled and one lead for TX and other 2 leads for RX. RX is connected to gnd in search head on previously described way.
Cable is usually wounded in spiral arround bar.
So finally i discovered when device goes crazy i take spiral cable and moving it a bit up or down - sliding it on bar. In most of cases wild behavior disappears. In most of cases but not in all cases?
Sometimes i punch device box hard and falses disappear, sometimes dont.
I turned all possible pots and switches wildly during falses to spot if there is any possible break in cicruitry - but not.
So finally only moving spiral of cable up or down on bar can realtivlly solve the problem.
So i am thinking some intereferences occuring in cable spiral randomly.
Is it possible?
This is occuring only in TGSL version. I havent noticed simillar with TGS made on large pcb so far. Oh yes, once but it was short lasting problem.
Same behavior i had in the past with my Classic III handmades. Those usually worked very good but ocassionally perfomed same problematic falsing and chattering.
So...i am a bit confused? Is it cose of cable? I must change cable for good. Must find some other type o cable.
Can you tell here exactly what cable you are using?
Can you make photo or sketch.
This is long lasting problem i noticed from the first device i made. But in the past it was rare. Now at last several devices this problem is occuring frequently.
Actually in that moment it is irelevant if i lift coil away from soil or lower it down. Falses and chatters are constant. I tried to fix it with GEB knob, but it doesnt influencing this behavior at all.
So i imagine this as sudden appears of some static currents in cable. Those "staying" currents are there and resident until i do something randomly and than "disharge" those currents somehow.
I was thinking somehow to change something crucial in design to avoid this in future. But what? I was thinking to relocate RX cap 15nF from pcb to search head or ...??? I really dont have a clue. Once i tested with cap in coil and sensitivity was much less. Detection was poor.
Only one thing here interesting me much; is it possible that cable could "suck" up some interferences or other possibilty - cable to "load" some static currents in short time and it will distort RX permanently until i do something to "disharge" that load. By twisting and moving cable spiral up or down sliding on the bar or something simillar???
Very hard to locate problem itself. Once i locate it, it will be piece of cake to solve it. Damn!
Everybody here ...help!
Hey Carl,Sean....what do you think on this?

[Max]

I have measured at tx coil pcb side.
My story :
I was confused from tickness of two kind of wire.
I have made a coil DD255 110w tx 120w rx resonating ( tx ) at 13.4Khz.
I have adjust tx capacitor to 16800 pf and rx capacitor to 11500 pf,
to obtain the right frequency ( with a good increase in sensibility ) and the right phase shift in rx.
I am planning to rebuild the coil with this wire (real awg30),
with 100w tx 105w rx I think it' s my right condiction
(i will check tx before cutting wire).

Regards

Junko

Hi,
use 100/105 ratio and you'll be fine with 30AWG wire. Look at my previous stuff /pictures (you have to dig posts) to get right dimensions.

Kind regards,
Max

[junko]

Thanks.
Glad to here you make it work finaly.
From which points did you measure the frequency?

I have measured at tx coil pcb side.
My story :
I was confused from tickness of two kind of wire.
I have made a coil DD255 110w tx 120w rx resonating ( tx ) at 13.4Khz.
I have adjust tx capacitor to 16800 pf and rx capacitor to 11500 pf,
to obtain the right frequency ( with a good increase in sensibility ) and the right phase shift in rx.
I am planning to rebuild the coil with this wire (real awg30),
with 100w tx 105w rx I think it' s my right condiction
(i will check tx before cutting wire).

Regards

Junko