TESORO GOLDEN SABRE

[Geo]

There is bus line Belgrade-Sokobanja twice daily....I am not sure about termin...If you come with car than it is 2 hours of driving in one direction.Also if you come with ca than you must pass highway, 30km away from Sokobanja...
Do you have Route66 Europe? Or Microsoft Autoroute? Easiest way to image this. I can send you plan with directions if you want?
But if you come with plane than you'll go directly to BG...
What was with your Anker?
Can you perform some fast air tests with few items? Coin 1cm, coin 2cm, Cola can.....

Hi Ivica. I will come with Bus (all the team will come with Bus).
About Anker ........... i have n't make the tests because i have problem with TGS pcb. When i will finish the TGS then i will make the test and to compare the detectors.
When I try to present the pcb it is dissolved immediately the photosensitive material. Maybe bad photosensitive material. I made about 10 pcbs without results . I think it is time to leave all these.......... maybe i am very old for these
Aby comment????
Regards

[ivconic]

Toss it! I had simillar situation once.You may use thin marker and draw lines over photoprint....

[Geo]

Toss it! I had simillar situation once.You may use thin marker and draw lines over photoprint....

Years are years .
I can't see so good

[Max]

Agree.That's why put tha 1M resistor as KT315 suggested.Much better audio response. But than bleeping occured!? Somehow i am wandering in the circle!? I do have oscilloscope, but better if i dont! It is old, obsolete,one channel and without internal synchro...!? Very,very old....Must buy new one asap!
BTW your story justify another thing; Relic Hawk is probably the best VLF ever....yet without speaker! Only earphones available with it...

Hi Ivconic,
with these controls:

- sens at max
- disc at min
- notch pot at min
- notch off

No bleeping at all. Nothing on air. Nothing in medium soils, detection is really good and deep.

I noticed that moving the disc pot further (say to the middle or more) and moving forward the notch pot (even with notch-off) I get sometimes some erratic bleeping due to maybe closed path and hi amplification. Probably supply rail is where the noise find its path to op. amps.

The problem was really huge with TL062 in place... that I've removed for the TLC2262.

You haven't notch on TGSL so it's not your problem there... but I think that a filtering on e.g. first preamp. would be always good... even if hi CMRR of modern op amps often don't require filtering for that.

Best regards,
Max

[Max]

Actually, this is very simple to measure. See attached image.
Switch to All Metal mode, and connect scope to point marked GEB. Then adjust GEB control until you have 0V DC. This should also work with a meter instead of the scope.

Hi Qiaozhi,
thanks for the hint...the other method! you gave me before...but I always follow the gate signal and RX one...to figure out the zero-crossing. I think that this is really useful for people that haven't or cannot use scope the right way... for one reason or another.

Kind regards,
Max

[Max]

Hi Ivica. I will come with Bus (all the team will come with Bus).
About Anker ........... i have n't make the tests because i have problem with TGS pcb. When i will finish the TGS then i will make the test and to compare the detectors.
When I try to present the pcb it is dissolved immediately the photosensitive material. Maybe bad photosensitive material. I made about 10 pcbs without results . I think it is time to leave all these.......... maybe i am very old for these
Aby comment????
Regards

Hi Geo,
you can try reducing time of exposition... and making the solution more weak... to give you more time when removing eccess resist from it... but it could work or not depending of status of photoresist... sometimes the alteration is on 100% of it so you simply cannot reach your result with it.

Heat is the big problem for conservation of that boards... then time is the second critical factor (1-3 years good, 3-7years still good, more than 7years... is a challenge!)

The big problem with lowering the time is that some resist could remain there ! and is very tricky finding the right "seconds" of UV (yes seconds) you need to remove it good from board.

One time I repeated 22times the procedure to get a working PCB from old stuff...more than 10years old. After that I've made it good... but then considering the time and efforts required... it isn't any good and so I recovered boards and painted with new photoresist can all them. And now I make smaller PCBs at first attempt with them!

If you have many boards of good quality... I suggest you clean them one by one and buy a can to repaint again with fresh resist (I've done 35 small 10cmx8cm using a 12eur can), then find a cool place to store using a black paper or similar to cover from light.

Best regards,
Max

[ivconic]

- sens at max
- disc at min
- notch pot at min
- notch off

Huh! When i adjust:
- sens at max
- disc at min
I'll get bedlam of bleeps!!! Usually no bleeps if Sens at "6" and Disc at "2", if we consider pot scale as from "0" to "10"...
So!? If these works for you, than something is much different between my and your detector? What?
I had Minelab Musketeer Advantage on service last month. After fixing minor problem i tested it. Behavior was simillar to my TGSL. When Sense on it adjusted over "7" Minelab start screaming, Disc level hadnt influence...
So i thought it was normal...
What should be the problem here?!
Huh!

[Max]

- sens at max
- disc at min
- notch pot at min
- notch off

Huh! When i adjust:
- sens at max
- disc at min
I'll get bedlam of bleeps!!! Usually no bleeps if Sens at "6" and Disc at "2", if we consider pot scale as from "0" to "10"...
So!? If these works for you, than something is much different between my and your detector? What?
I had Minelab Musketeer Advantage on service last month. After fixing minor problem i tested it. Behavior was simillar to my TGSL. When Sense on it adjusted over "7" Minelab start screaming, Disc level hadnt influence...
So i thought it was normal...
What should be the problem here?!
Huh!

Hi,
yes is really strange. I noticed that with different components things change very much in TGS working about that... I mean noise.

I think your problem could be at LM308s if they are not original ones... I got enormous noise from the fake ones I bought some time ago...and at that time I really was impressed by that... before I had start thinking they aren't true National's parts.

Then replaced with secure originals I got much less noise... and good stability as described. Also with changing and testing TL071 and TL081 I noticed that but noise is always not much with those too.

With ST TL071 parts I got absolutely no bleeping at max sens.

But all these considerations are empiric... we have to look forward to insulate better the problem source. I strongly think that some kind of feedback occours between output comparators and preamp. along the supply rail, of course I'm not sure of that but solved the middle noise (fake LM308s) I suppose this could be the cause of bleeping at higher-max sens.

I think that problems are mainly noise from ICs but then, lowered noise, also propagation along supply line could be an issue.

I'm start thinking that an higher CMRR preamp will do better instead of LF353... but problem is finding as good sensitive as it for this design, and we know it's not easy.

LF353, if I remember well, has minimum CMRR of 70dB... not very good for a preamp directly connected to the same supply rail of output stages !

There are a lot with 120 or 130dB CMRR... much better but they lack on sensitivity cause of the input stage... example is the OPA227 with CMRR of 138dB ! Damn good... but I haven't and so I can't test it as preamp.

Best regards,
Max

[Max]

Hi Qiaozhi and all,
I'm reading the George Payne's article... JC1 posted the link yesterday.

Found all very interesting... maybe I've read before... don't remember now.

Anyway, my problem now is on conventions

I mean in the Payne's article I read that ferrite rod gives "zero" point... ok... then I've looked again at an old patent of Jack Gifford and he said that pure mineral give RX shift of -90° : all fine, I remember this also.

But then Payne call it zero and Gifford -90° (referred to the osc signal).

I think that -90° is the right way... of saying that thing...

Then Payne wrote that normal ground could fall between 0° and -5° of shift... so more negative of ferrite imposed shift.

QUESTION IS: that means soil could give a shift from -90° to -95° or from -90° to -85° ???????

Kind regards,
Max

[Qiaozhi]

- sens at max
- disc at min
- notch pot at min
- notch off

Huh! When i adjust:
- sens at max
- disc at min
I'll get bedlam of bleeps!!! Usually no bleeps if Sens at "6" and Disc at "2", if we consider pot scale as from "0" to "10"...
So!? If these works for you, than something is much different between my and your detector? What?
I had Minelab Musketeer Advantage on service last month. After fixing minor problem i tested it. Behavior was simillar to my TGSL. When Sense on it adjusted over "7" Minelab start screaming, Disc level hadnt influence...
So i thought it was normal...
What should be the problem here?!
Huh!

The difference is probably in the coils, as you have made your own. Do you both have the same phase shift between the RX and TX signals?

[Max]

The difference is probably in the coils, as you have made your own. Do you both have the same phase shift between the RX and TX signals?

Hi,
yes could be... but I've made my large coil using his data... getting just 90Hz difference at TX freq. All really closed I think to his coils.

That's why I think could be a components problem.

Kind regards,
Max

[Qiaozhi]

Hi Qiaozhi and all,
I'm reading the George Payne's article... JC1 posted the link yesterday.

Found all very interesting... maybe I've read before... don't remember now.

Anyway, my problem now is on conventions

I mean in the Payne's article I read that ferrite rod gives "zero" point... ok... then I've looked again at an old patent of Jack Gifford and he said that pure mineral give RX shift of -90° : all fine, I remember this also.

But then Payne call it zero and Gifford -90° (referred to the osc signal).

I think that -90° is the right way... of saying that thing...

Then Payne wrote that normal ground could fall between 0° and -5° of shift... so more negative of ferrite imposed shift.

QUESTION IS: that means soil could give a shift from -90° to -95° or from -90° to -85° ???????

Kind regards,
Max

Yes - there's a lot of confusion here, and I think it's done on purpose.
It appears to me that it really depends on where you place your reference point. Also, there is an assumption that these values represent the actual phase-shift produced by the various targets. In reality they seem to be the value of the phase-shift required to reject the particular target, and will once again depend where you set your reference point.

For example, first set up your detector to reject iron. i.e. with the sample pulse for the DISC channel located at the peak of the RX signal. Note this position. Then rotate the DISC control until you can just reject a pulltab. Measure the phase shift between the two positions. I expect you will find it is somewhere between 80 and 110 degrees, depending on the type of pulltab. This matches Gifford's patent.

Also, in the patent, minerals are shown at -90. This refers to the mineral sample point (phase "X") and does not literally mean "minerals". To discriminate against mineralized soil (i.e. contains some iron) we would need to add up to 5 degrees, and -90 +5 = -85 degrees. But again, this is somewhat confusing, because we really need to adjust the GEB channel to ignore mineralized soil, not the DISC channel. In this case, we need to subtract 5 degrees.

You just need to make yourself a coffee, and draw a few diagrams to get your head around this. And (of course) do some scope measurements on the circuit.

[Qiaozhi]

Hi,
yes could be... but I've made my large coil using his data... getting just 90Hz difference at TX freq. All really closed I think to his coils.

That's why I think could be a components problem.

Kind regards,
Max

That's not what I meant.
Monitor the TX signal on channel 1 of the scope, and the RX signal on channel 2. Then measure the phase-shift between the two.

[Max]

That's not what I meant.
Monitor the TX signal on channel 1 of the scope, and the RX signal on channel 2. Then measure the phase-shift between the two.

Hi,
oh sorry... yes right could be important to compare.

I've done already some time ago and read RX signal some few degrees ahead +3 or +4° (probably due to shield) respect to TX... or well... now I remember that's so... I don't used much care measuring it cause coils worked really good.

Best regards,
Max

[Max]

Yes - there's a lot of confusion here, and I think it's done on purpose.
It appears to me that it really depends on where you place your reference point. Also, there is an assumption that these values represent the actual phase-shift produced by the various targets. In reality they seem to be the value of the phase-shift required to reject the particular target, and will once again depend where you set your reference point.

For example, first set up your detector to reject iron. i.e. with the sample pulse for the DISC channel located at the peak of the RX signal. Note this position. Then rotate the DISC control until you can just reject a pulltab. Measure the phase shift between the two positions. I expect you will find it is somewhere between 80 and 110 degrees, depending on the type of pulltab. This matches Gifford's patent.

Also, in the patent, minerals are shown at -90. This refers to the mineral sample point (phase "X") and does not literally mean "minerals". To discriminate against mineralized soil (i.e. contains some iron) we would need to add up to 5 degrees, and -90 +5 = -85 degrees. But again, this is somewhat confusing, because we really need to adjust the GEB channel to ignore mineralized soil, not the DISC channel. In this case, we need to subtract 5 degrees.

You just need to make yourself a coffee, and draw a few diagrams to get your head around this. And (of course) do some scope measurements on the circuit.

Hi,
I'm drinking the coffee... and I remembered all the story about confusion and references

In the Gifford's (well is my reading of it) system the reference is on the Y axe and positive are clockwise measured:
at -90 (-X axe) he has ferrite response... and clockwise turning a +5° he has the "limit" for soil if we talk about Payne's stuff so: -90+5 = -85°

Actually he has mixed up stuff too on figure nr. 2 of patent giving an "alternative" way (compare fig.1 and fig.2 ... in fig.2 the +R axe that lay at +90 is actually the origin for fig.1 , with phase equals zero)!

Payne's coordinate system uses also an axe as reference for angles BUT counterclockwise for positive angles ...so Payne's -5° describe a movement like +5° for Gifford (here the confusion):

when he said that ferrite is zero he means that he's in the origin, on the reference axe, with the ferrite response... and when he said that a soil could give till -5° he means that conductive (R component) make RX signal shift phase clockwise respect to ferrite response (pure mineral)... like happens when a conductive metal effect is detected.

The confusion is in that Payne's method uses negative angles for effects due to increasing conductance ... where Gifford's uses the positive for that.

That's why I think Gifford's method is better... cause when can talk of negative phase for e.g. iron... and positive for silver... and not the opposite.

Of course, just conventions... but all this stuff is really confusing changing the reference all the times.

Kind regards,
Max