TESORO GOLDEN SABRE

[ivconic]

Sorry Max!
What was the question?
Last days i am very rare near my pc. Usually do check this forum pretty skim..
Come again.

[Max]

Sorry Max!
What was the question?
Last days i am very rare near my pc. Usually do check this forum pretty skim..
Come again.

Hi,
no problems... just I asked you about what do you think of disc in Tesoro's designs.

Qiaozhi pointed right way when said that original coils give always left shift on RX signal, no matter if target is ferrous or non-ferrous.

Also, non-ferrous give a rise in amplitude at RX coil and ferrous give instead a drop.

The question was/were:

What do you think of how Tesoro's disc works if phase shift is always one way ? Is it related instead to amplitude rise/fall only ?

Cause I think the important information there is about amplitude if phase shifts are always same side...

Kind regards,
Max

[ivconic]

Hi,
no problems... just I asked you about what do you think of disc in Tesoro's designs.

Qiaozhi pointed right way when said that original coils give always left shift on RX signal, no matter if target is ferrous or non-ferrous.

Also, non-ferrous give a rise in amplitude at RX coil and ferrous give instead a drop.

The question was/were:

What do you think of how Tesoro's disc works if phase shift is always one way ? Is it related instead to amplitude rise/fall only ?

Cause I think the important information there is about amplitude if phase shifts are always same side...

Kind regards,
Max

Actually i noticed pretty unsignificant phase movements to both sides related to type of metal. This is mostly due fact that i dont have good scope. My is old,obsolete and totally unaccurate. Yet,with same scope i noticed large amplitude jumps on various metals. Most significant is huge amplitude jump on ferrite rod - but without any sound, which leads me to conclusion that GEB/DISC stage works almost perfect at TGSl. Same perfection i experienced so may times on real field,under real condition. That's why i am pushing this project as most suitable for to be hand made.Really easy to achieve excellent performances.
Unlike at other principles, the way how GEB/DISC is soluted at TGS (and few other Tesoros) turns to be most efficient when compared to most of other analogue designs.
I've done many copies of White's Classic III so far. At that specific design GEB suffering from to many lacks which directly influencing further DISC stage. Fer instance, although CL3 do have extra resistance switch to rise "imunity" on hot rocks and black sand, still it is suffering much from those. Other hand, TGSL does not "see" hot rock even big like a house! Splendid!
On same terrains where i had much of hot rock signals and therefore much problems....on those very same terrains i do not have problems at all with TGSL.
This is just an example which will help you to understand differences in this approach by Tesoro.

[Qiaozhi]

Hi,
I'm not sure... but think Qiaozhi report is valid only for concentric coplanar coils, expecially original tesoro's ones.

I have a 9x8'' spider from tesoro and on my TGS I see RX signal go to the left not to the right, as Qiaozhi stated.

Probably also you have reversed rx leads, try to swap them and let us know if it goes to the left then.

Kind regards,
Max

This might be true. I think it is ok for the phase-shift to be to the right, but in that case you need to swap over the RX leads. The important thing is that the signal at the output of the sample gate in the GEB channel must increase in amplitude when a metal target passes next to the coil. If it decreases, then swap the RX leads. I don't remember if the DD coil has the same characteristics as a concentric - need to recheck this.

[Max]

This might be true. I think it is ok for the phase-shift to be to the right, but in that case you need to swap over the RX leads. The important thing is that the signal at the output of the sample gate in the GEB channel must increase in amplitude when a metal target passes next to the coil. If it decreases, then swap the RX leads. I don't remember if the DD coil has the same characteristics as a concentric - need to recheck this.

Hi Qiaozhi,
let me ask same question to you:

what about disc in Tesoro's... it's made just by amplitude variations at RX signal then ?

I noticed that phase shift is always one way with 9x8'' original coil... and this fact is really interesting cause disc works perfect on TGS/TGSL like Ivconic stated!

Now the problem is... that I cannot recognize the stuff that is in the Gifford's patent with behaviour of device: I have no left or right phase shift related to target composition, like expected, but just amplitude variations(rise for non-ferrous and drop for ferrous) and always same left phase shift there, with both ferrous and non-ferrous.

Also, like you described the GEB signal always goes up with both kind and of course ferrite material.

The strange if that on some handmade DD I have I got different stuff, and disc works also perfect ! I got left and right shifts in that coils, but always the same amplitude rise/fall behaviour.

That's why, I think, disc is mostly related to amplitude variations at RX, not phase in Tesoro's designs that then give alway-rise on GEB channel and rise/fall at disc channel depending on material.

The effect is the same at the end... but does not rely on phase shift between RX signal and TX signal as one could expect from reading the patents.

It's a puzzle !

Kind regards,
Max

[Qiaozhi]

Hi Qiaozhi,
let me ask same question to you:

what about disc in Tesoro's... it's made just by amplitude variations at RX signal then ?

Essentially this is correct. This is the way the older T/R detectors manage to discriminate ferrous from non-ferrous, simply by an amplitude change. Only the good stuff causes the amplitude to increase.

I noticed that phase shift is always one way with 9x8'' original coil... and this fact is really interesting cause disc works perfect on TGS/TGSL like Ivconic stated!

I have also tested other Tesoro concentric coils, and they all have the same phase-shift to the left.

Now the problem is... that I cannot recognize the stuff that is in the Gifford's patent with behaviour of device: I have no left or right phase shift related to target composition, like expected, but just amplitude variations(rise for non-ferrous and drop for ferrous) and always same left phase shift there, with both ferrous and non-ferrous.

The Gifford patent is confusing because the reference point for the phase measurements is offset by 90 degrees.

Also, like you described the GEB signal always goes up with both kind and of course ferrite material.

The strange if that on some handmade DD I have I got different stuff, and disc works also perfect ! I got left and right shifts in that coils, but always the same amplitude rise/fall behaviour.

It is possible to construct your own coil with different characteristics than the 9x8 concentric, and with some adjustments it can be made to work. However, these configurations are not optimal.

That's why, I think, disc is mostly related to amplitude variations at RX, not phase in Tesoro's designs that then give alway-rise on GEB channel and rise/fall at disc channel depending on material.

The effect is the same at the end... but does not rely on phase shift between RX signal and TX signal as one could expect from reading the patents.

It's a puzzle !

Kind regards,
Max

Although the basic mechanism for discrimination relies on a change in amplitude at the output of the DISC channel, it is also affected by phase changes. By adjusting the DISC control you can alter the sample point on the received waveform in order to reject higher conductivity targets. It is not only Tesoro that use this method of discrimination. This is the same technique used by Whites, Fisher, Viking, C-Scope, etc., in their analog detectors. The digital detectors that have some sort of VDI indication, are actually measuring the phase-shift.

It's not really a puzzle .... just a bit confusing.

[Max]

Essentially this is correct. This is the way the older T/R detectors manage to discriminate ferrous from non-ferrous, simply by an amplitude change. Only the good stuff causes the amplitude to increase.


I have also tested other Tesoro concentric coils, and they all have the same phase-shift to the left.


The Gifford patent is confusing because the reference point for the phase measurements is offset by 90 degrees.


It is possible to construct your own coil with different characteristics than the 9x8 concentric, and with some adjustments it can be made to work. However, these configurations are not optimal.


Although the basic mechanism for discrimination relies on a change in amplitude at the output of the DISC channel, it is also affected by phase changes. By adjusting the DISC control you can alter the sample point on the received waveform in order to reject higher conductivity targets. It is not only Tesoro that use this method of discrimination. This is the same technique used by Whites, Fisher, Viking, C-Scope, etc., in their analog detectors. The digital detectors that have some sort of VDI indication, are actually measuring the phase-shift.

It's not really a puzzle .... just a bit confusing.

Hi,
thanks, now I understand it better: is more complex than what I expect from Tesoro's VLFs disc section but sure, it works pretty good.

I don't know if what I made about DD is optimal but I get really good results with them and disc is perfect. I think Ivconic's recipe for the large DD coil is perfect for it, I have no dubt about that cause made different and not a single one will beat that numbers on TGS within same diameter and shape.

The fact phase shift is both sides with DD means really few if detector actually rely on disc channel amplitude rise or fall to say about target composition.

I think the real trick is made on amplitude changes... if the coil will give a rise with non-ferrous and a drop with ferrous it will works good on TGS, with minor impact of TX/RX phase shift when no target, just need something 200° out of phase to avoid troubles with sync.

The interesting thing is that , a TGS will not actually compute the phase shift but just comparing amplitudes at both GEB-disc channels. This way a very essential disc indicator could be realized using an e.g. differential amplifier connected with e.g. some bicolor led... very easy stuff and reliable also.

No need to compute phase shift, no need of accurate phase meter there... just some amplifier and maybe an hold circuit + analog instrument is enough to understand what kind of metal is detected. Old way...

Kind regards,
Max

[nelson]

Yesterday i null with the scope very easy the same coil, but know i need to know how to do fine tuning of the RX coil. Should i use caps parallel to each lead of RX coil? If so wich value should i have to use?.
This questions is because i had noted that sensitivity of my TGS is to poor, a 27 mm coppper coin is just detected at 18 centimeters.
TX coil is working at 14.6 Khz.
Any help, please write about.
Thanks
Nelson

Hi,
use Ivconic's data:

TX= 100turns
RX= 105turns

wire 30AWG (0.25mm bare diameter, without varnish); you can use 0.30mm but require change a bit turns.

Coil diameter will be around 27cm DD type.

Null at less than 15mV peak-peak

Resistance is for each coil... around 20ohm and you have match tx frequency of 14.5 - 14.7Khz.

Kind regards,
Max

[Molzar]

Hi,

Did some more testing, All aspects of descrimination, sense, and notch feature work properly. Coils are connected properly, still Rx always shift to the right when triggering on Tx. First gate of GEB (LM358, pin7, Max's Test point #9) rise when metal exposed to coil, like Qiaozhi said.

Problems are some erratic noises and only 18-20 cm depth on 2cm copper (or silver coin) Using LM308 or TL081 same. Only changes from schematic are 4.7ZD instead 4.3ZD, 3.9K instead 3.3K, and am using 10K instead 2.2K (or 33K) like Ivconic suggested, sound seems good. LF442 is TLC2262, FETs are TIS75s.

Haven't made many DD coil, but have made many PI coils. Am using 30 AWG enameled wire 100 and 105 turns wound on fixture (see photo), 0.8mm thick spiral wrap to bind coil, then .05mm thick aluminum foil for shield with 1 cm gap, then .2mm vinyl electrical tape to secure all. Null is ~8mV pp. Below are some photos. Sorry for the crappy images....

Any suggestions?

Many Thanks for everyones help, this has been a good (interesting) project!

Molzar

[detectoman]

una pregunta para alguno

a que calibre de alambre de cobre corresponden 022m.mm, y 030 m.m?
for your attention very thanks

[detectoman]

es correcto calibre 31 para 030 y cal 28 para 022?

[Qiaozhi]

Hi,

Did some more testing, All aspects of descrimination, sense, and notch feature work properly. Coils are connected properly, still Rx always shift to the right when triggering on Tx. First gate of GEB (LM358, pin7, Max's Test point #9) rise when metal exposed to coil, like Qiaozhi said.

Hi Molzar,

For the TGS, the TX frequency should be 14.65KHz and the RX must be tuned to 16.12KHz. So it's important to note that the resonant frequency of the RX circuit is higher than the TX. This might be causing the right-shifting of the phase if the RX frequency is lower. Otherwise, there is no reason why the DD and concentric should react differently, unless it's something to do with the physical construction. i.e. under or over-nulled.
Perhaps you could experiment with your setup, and let us know the results.

[ivconic]

"...Problems are some erratic noises..."

I heard this from many people recently. Among 22 devices made so far, i also had few cases, where some ocassionall chatters and noises occurred.
Really...I dont have universal solution to solve this problem. Usually it is about bad coil.
I posted many posts arguing and explaining ONLY one proper way to null specially this DD coil for this TGS. Yet..very few memebers accepted my
advices.
Do not null coil using RX stage outputs (LF353)...WRONG!
Null exact coil for exact TGS using only its TX output connected to TX coil and RX coil leads connect directly to milivoltmeter, BUT NOT TO TGS!
I know...few experts here will again deny my claims and method, explaining theoretically why it is not proper.
Do i give a sh*t? Of course not.
My TGSL's and coils works excellent,calm and very "deep", despite "wrong" method i used to null them.
1e coin at 34cm in the air and 28cm in the ground. Rock stabile, no chatters, no falses. Perfect discrimination.
Only problem i do have with almost all TGSL's is weak audio. Not so loud.
Everything else is perfect.
I wish you success at the end.
After all....try my method and you will see.
Best regards!

[Molzar]

Hi Molzar,

For the TGS, the TX frequency should be 14.65KHz and the RX must be tuned to 16.12KHz. So it's important to note that the resonant frequency of the RX circuit is higher than the TX. This might be causing the right-shifting of the phase if the RX frequency is lower. Otherwise, there is no reason why the DD and concentric should react differently, unless it's something to do with the physical construction. i.e. under or over-nulled.
Perhaps you could experiment with your setup, and let us know the results.

Hi Qiaozhi,

This should be easy to prove by swapping the coils so the Tx is the lower frequency (higher inductance). Also if you take a look at Carl's coil data http://geotech.thunting.com/cgi-bin/...oils/index.dat the one Tesoro DD has the Tx as the higher inductance and all the concentrics are the opposite, Tx lower inductance.

I've read many posts on Tx frequency of ~14.6 KHz here, but where does the Rx frequency (16.12 KHz) you stated above come from?

Will try swapping coils tonight...

Thanks,

Molzar

[Max]

"...Problems are some erratic noises..."

I heard this from many people recently. Among 22 devices made so far, i also had few cases, where some ocassionall chatters and noises occurred.
Really...I dont have universal solution to solve this problem. Usually it is about bad coil.
I posted many posts arguing and explaining ONLY one proper way to null specially this DD coil for this TGS. Yet..very few memebers accepted my
advices.
Do not null coil using RX stage outputs (LF353)...WRONG!
Null exact coil for exact TGS using only its TX output connected to TX coil and RX coil leads connect directly to milivoltmeter, BUT NOT TO TGS!
I know...few experts here will again deny my claims and method, explaining theoretically why it is not proper.
Do i give a sh*t? Of course not.
My TGSL's and coils works excellent,calm and very "deep", despite "wrong" method i used to null them.
1e coin at 34cm in the air and 28cm in the ground. Rock stabile, no chatters, no falses. Perfect discrimination.
Only problem i do have with almost all TGSL's is weak audio. Not so loud.
Everything else is perfect.
I wish you success at the end.
After all....try my method and you will see.
Best regards!

Hi,
I think the problems are always there:
- fets commutations
- comparators

I noticed that also on BandidoII happened in past I got instability due to comparators : I haven't guard rings or something there. Also, on fet amplifiers no guard rings.

The problem I solved on bandidoII shielding lower side of critical parts... and I think a large copper plate to gnd will solve many of these problems also on TGSL (actually I have rock solid TGS but not solved yet... cause I test just from time to time, the problem on my TGSL board... that's really sensitive too but noisy).

The dang fet commutations are still a problem but I think the really weak ring is related to last comparators... too easy to commutate there if noise present... and adding inertia slow down all the operations there and that's no good.

I noticed Paul Panzer's project has large GND plane on upper side of board... that's the first thing I would like having on TGSL board but at now I cannot rebuilt it this way to see.

Kind regards,
Max