TESORO GOLDEN SABRE

[eclipse]

Hi Max, it's not AD.
Here is a picture of the device, looks old isn't it...?

[Max]

"Manifacturer logo looks like a triangle, can't recognize it."

Like this one ?

Kind regards,
Max

[eclipse]

Guys I trashed the damn board! I desoldered almost all valued components and I'm making new board for the TGS. Bolder traces, higher copper thickness, no ground plane..
(it could be the plane doing the nasty stuff around, I think I prefer the chatters for a starter)
--
I also needed some additional stuff (pots, diodes, etc) and had the chance to order few more ICs for testing so soon we will have BATTLES:

1. LF353 (metal can) vs LF353N (ST) vs LT1057 (LT) vs TL082 (TI)
2. LM393 (ST) vs LT1018 (LT)
3. LM308 (motorola) vs LT1008 (LT)
4. LM358 (ST) vs TL082 (TI) vs OPA2277 (BB-TI)

Funny thing is that the LF353 metal can looks old, perhaps 10 years old, taken from old russian TV Elektron
( and they are famous all around with the weight - more than 100 pounds, tons of parts I tell you ..)
Manifacturer logo looks like a triangle, can't recognize it.
We'll see how the Old timer works :P

PS: Check out the avatar I think it's the most appropriate!
Cheers

[Max]

Hi Max
It was working well later, I did what you said me , also you and Qiaozhi are right.
Theory is true, but it is strange .not any happen after Banded coils with tape.
Best regards.

Hi,
this is the good way of doing it, keep separate the shields of tx and rx coils.

I like this way.

Now, about poor results you have to optimize wiring also: read when Ivconic talk about short leads to e.g. panel socket etc all that is another key factor.

I don't like alligator clips there and that wire, why don't you try something shielded cable instead ?

Also, the CHAIR ! Are you sure the chair has no metal inside like iron rivets or nails ? Cause if so you could get lowered sens from detector too.

So, are all "details"... but are important when searching for optimum.

Kind regards,
Max

[aft_72005]

Hi,
you must have the gaps and you have but the overlap area covered with al foil is seen as a shorted turn by the MD. In that oval shape you have actually a conductive turn that's coupled with magnetic flux generated by oscillator: this produce strong eddy currents in that shielding , closed, loop that will damage your detection range.

So, put some e.g. tape between the two shields where they touch and you solve that problem.

Kind regards,
Max

Hi Max
It was working well later, I did what you said me , also you and Qiaozhi are right.
Theory is true, but it is strange .not any happen after Banded coils with tape.
Best regards.

[ivconic]

Hello Ivconic , If it chatters only at maximum sensitivity than it is a very slight circuit problem . And not the pcb board . Is your TGSL case Metal or Plastic ???............I fired and retired the "amtech2005" from this forum !!!! And is now Eugene52........I am now junior Super Tech here Cheers.............Eugene

Detector enclosures are from plastic. Yet, i keep front panel mostly to be metal. If not, than i usually put another piece of metal plate on inside of panel. If you observe my 1265 pcb, you can see some more Cu area at rear side, planned to hold metal "L" holder for coil jack. Also most shortes possible wires from pcb surface to jack. Ground plane is good and benefitial if used smartly, otherwise it can present "radiating" body in overall design; if to many loops incuded there.

[Eugene52]

TESORO GOLDEN SABRE

Hello Ivconic , If it chatters only at maximum sensitivity than it is a very slight circuit problem . And not the pcb board . Is your TGSL case Metal or Plastic ???............I fired and retired the "amtech2005" from this forum !!!! And is now Eugene52........I am now junior Super Tech here Cheers.............Eugene

[Max]

Hi Max
You are right , but I didn’t have short short circuit on coil.
The faraday shields at the transmitter . And receiver coils open in the region
Of gap .
Please more explain .
Best regards.

Hi,
you must have the gaps and you have but the overlap area covered with al foil is seen as a shorted turn by the MD. In that oval shape you have actually a conductive turn that's coupled with magnetic flux generated by oscillator: this produce strong eddy currents in that shielding , closed, loop that will damage your detection range.

So, put some e.g. tape between the two shields where they touch and you solve that problem.

Kind regards,
Max

[ivconic]

Just saw this photo on other thread; justify my doubts about pcb.
Seems they also reconsidered S/N issue and made nice ceramic pcb, smallest as possible to improve ratio....ha,ha,ha...dirty trick!

Usually ground potentials at lowest frequencies presents sort of "sucking antenna" for various interferences. In audio technique is imperative to reduce those at very minimum, cose everything is later pretty audible in speaker. So usually when projecting audio preamps and amps, designer tends to form ground loops at one and only spot on pcb. Many loops will degrade S/N ratio more and more. We can freely observe metal detector as sort of audio device, dealing with very low frequencies. So pcb design is more than important here, among other important things.

[ivconic]

If the schematics we use are close to accurate , and the parts we use are new , or within tolerance . 1. Then noise or chatter is caused by poor PCB quality or Oscillations caused by improper pcb layout or ground circuit traces not right . 2. If there was a way to do a signal to noise test without the search coil hooked up but using only a resistive rx and tx load on the Golden sabre light and then apply power and find out where the self oscillations or external interference is causing our Project Problems , that would be great !!..........I am very optimistic that the Tesoro Golden Sabre Light problem's will be solved very soon.......................Eugene

Not to worry much if chatters appear only when Sense is highly adjusted. Cose i saw same behavior on original Vaquero and Tejon, same story.
Somehow i managed to reduce those chatters by evolving pcb. Last one drawn for 1265 enclosure seems to "produce" least possible chatters. I made one device for my own needs. Oftenly go outdoor and search for items. On most of the soils no chatters at all when Sense on "9" and sometimes on "10". Also coil is very important. I made very small coil for some hard and pretty slope terrains, 18cm diamm. coil. So i noticed high stabillity with that coil.
Most of the time i work with maximum sense, using that coil. That coil air tests are modest comparing 27cm coil, 1e maximum at 26cm ...etc...etc.. but rock stabille on very hard soil, as showed to me already.
So actually, i dont think that we have problem here with schematic accuracy. It is more like the method of making detector and coil. Every step is important. Every "small" thing is actually very important.
Badly nulled coil can also cause often chatters and crack in audio at detection borders...
However, fact is that TGS audio is not state of the art, and need major improvement.
Regards...

[aft_72005]

Max

If you'll not remove that short circuit at coil your MD will never work any good.

Hi Max
You are right , but I didn’t have short short circuit on coil.
The faraday shields at the transmitter . And receiver coils open in the region
Of gap .
Please more explain .
Best regards.

[amtech2005]

TESORO GOLDEN SABRE

If the schematics we use are close to accurate , and the parts we use are new , or within tolerance . 1. Then noise or chatter is caused by poor PCB quality or Oscillations caused by improper pcb layout or ground circuit traces not right . 2. If there was a way to do a signal to noise test without the search coil hooked up but using only a resistive rx and tx load on the Golden sabre light and then apply power and find out where the self oscillations or external interference is causing our Project Problems , that would be great !!..........I am very optimistic that the Tesoro Golden Sabre Light problem's will be solved very soon.......................Eugene

[Max]

I'm gonna slow the things now with this board by making second for testing purposes, with copper layer much bolder, this one is ~35um which seems bad when you start desoldering components. First and last time I'm buying such crap, from now only 70um and up.

I rushed the things too much, I need to detail study and scope all. Also in my mind rotates the idea of first making TGS like all of you guys, I mean no innovations. Why? As I told before



I'm risking here to become annoing with questions, while I can avoid some of
them if I make same like your boards. All those new IC, perhaps some of them don't work as good as expected. Up to now I have the feeling that LT1057 is
not good somehow, though is improved replacement of LF353.

A tip: with adjusted coil almost all scope points are different (I'm mainly looking at those from Max, pg 57 ).

From the observations I noticed that PN2222 - Fairchild (plastic)is much better than 2N2222 - Thomson (metal) - ( I switched the one connected to 4024 with 1K, which was reversed ). Could be single unit, problem or it's old ( damn it really looks old).. but still we don't get enough for what we're paying.. always got to look for deffects.

Cheers.

Hi,
had trouble too with 35um... also the problems Ivconic's explained : small scratches on the surface made them tricky to debug... almost invisible break in the tracks!

I found that many of these defects originate in bad storage procedures at dealers warehouse...

In some of these presensitized UV boards I use I noticed a lot of scratches on the adesive film that covers the UV sensitive varnish layer: that are the troubles... the scratches propagate even under the protective film and then is very easy the varnish will result broken cause of that.

When you etch the board seems everything ok...but it's isn't. I found that checking all them is too time wasting... so I throwed away them all remaining and bought new from another dealer with improved protective film and more thickness too.

The 35um are too sensitive to storage problems and scratches on the varnish... thus lead easy to circuit failures really hard to find later: this is expecially when you etch boards in very fast solution... that dissolve anything in 6-8 minutes!

Kind regards,
Max

[eclipse]

I'm gonna slow the things now with this board by making second for testing purposes, with copper layer much bolder, this one is ~35um which seems bad when you start desoldering components. First and last time I'm buying such crap, from now only 70um and up.

I rushed the things too much, I need to detail study and scope all. Also in my mind rotates the idea of first making TGS like all of you guys, I mean no innovations. Why? As I told before

"I fixed some stuff making troubles, found others."

I'm risking here to become annoing with questions, while I can avoid some of
them if I make same like your boards. All those new IC, perhaps some of them don't work as good as expected. Up to now I have the feeling that LT1057 is
not good somehow, though is improved replacement of LF353.

A tip: with adjusted coil almost all scope points are different (I'm mainly looking at those from Max, pg 57 ).

From the observations I noticed that PN2222 - Fairchild (plastic)is much better than 2N2222 - Thomson (metal) - ( I switched the one connected to 4024 with 1K, which was reversed ). Could be single unit, problem or it's old ( damn it really looks old).. but still we don't get enough for what we're paying.. always got to look for deffects.

Cheers.

[simonbaker]

"...Sensitivity pot act like.. well actually doesn't act a bit...."
There is not any "secret" schematic of TGSL

That was joke of course -- secret is experience and knowledge.

Regards,

-SB