TESORO GOLDEN SABRE

[ivconic]

I think that you have right.But for me only available pf caps are ceramic.Could it be this 10pf?
For tests now I don't use speaker but headphones directly tied on speaker place.
Also waned to ask you about 4024 pin 1.What shape should have the signal?Because I see same shape like on gates.Is this ok or should be sinus?

Funny thing; i never scoped that point!?
But certainly it is not sinus, must be squared a bit...at least. That's buffer transistor 2N2222 is there for.

[Ultimate_Haze]

I think that you have right.But for me only available pf caps are ceramic.Could it be this 10pf?
For tests now I don't use speaker but headphones directly tied on speaker place.
Also waned to ask you about 4024 pin 1.What shape should have the signal?Because I see same shape like on gates.Is this ok or should be sinus?

[ivconic]

Ok,
I will follow your lead.And search between gates and 358.
But if coil moved over night,why now I cant co lower then .200/2V?Must be noise interface.That make my live hard.
The signal from LF353 pin 1 is not sinus.Its strange.Will make some pictures.Have you check on good TGSL how it looks?

Coil somehow changed it's features!? If coil was not fixed exactly after nulling, than it is expectable to "move" after some time. Usually temperature changes affects coil and provoke relative movements. Especially if wires are not constrained good.
...
Signal from 353 must be good sinus. If not, than some component is distorting it.
Which one? Caps in most of the cases. Not only by changing values but also by bad quality.

[Ultimate_Haze]

Ok,
I will follow your lead.And search between gates and 358.
But if coil moved over night,why now I cant co lower then .200/2V?Must be noise interface.That make my live hard.
The signal from LF353 pin 1 is not sinus.Its strange.Will make some pictures.Have you check on good TGSL how it looks?

[ivconic]

Hello,
So there is possibility that everything on pcb is ok and still device can't reach good depths?And this is with good coil?
So I will just make another one and see if there are differences.I test every new coil also with two other TGSLs/BD140/and one TGS.
Yesterday I try to null last coil better and I get down to 0.004/200mV.And today switch on the setup as I leave it and read .940/2V.Its not the multimeter.Must be noise from TVs,security radios,cells,etc.
When I tune it were late.And maybe less of those.
I wont quit on this also.

The best that I reached is with BD140 version.With 22cm coil/22cm in air for 1e coin.
Now I remember that you use 4K7 for R13 and R14.I have mount 5K1.I will try now to see is there any change.

SB glad that you are back on this too.
now, cannot participate.
Why?

4K7 or 5K1...doesn't make any significant difference.
Your coil "moved" over night, i am sure.
"..now, cannot participate.."
Of course i can!? I can't exactly do everything i usually can, due low temperatures in my workshop (no heating there). But i can participate with present experiences i have.
..
If you want to experiment than i can suggest you to pay attention on parts between gates and audio stage.
First fix that coil and preserve it from further movements.
Than remove speaker away from pcb for at least 20cm (use longer wires).
Be sure that your coil is on some plastic (non conductive) substratum, away from metals and noise sources.
Nulling must be done away from metals and noises so as further experimenting.
Signal have losts somewhere between gates (fets) and last LM358, so as i noticed. I am not sure exactly where?
Keep us informed here.
Regards!

[Ultimate_Haze]

Hello,
So there is possibility that everything on pcb is ok and still device can't reach good depths?And this is with good coil?
So I will just make another one and see if there are differences.I test every new coil also with two other TGSLs/BD140/and one TGS.
Yesterday I try to null last coil better and I get down to 0.004/200mV.And today switch on the setup as I leave it and read .940/2V.Its not the multimeter.Must be noise from TVs,security radios,cells,etc.
When I tune it were late.And maybe less of those.
I wont quit on this also.

The best that I reached is with BD140 version.With 22cm coil/22cm in air for 1e coin.
Now I remember that you use 4K7 for R13 and R14.I have mount 5K1.I will try now to see is there any change.

SB glad that you are back on this too.
now, cannot participate.
Why?

[ivconic]

I also intend to remove speaker from detector enclosure and place it somewhere on shaft...most probably under the elbow part (simillar to Garrett GTI 2500).
Why? Because i noticed that speaker is source of many problems, if placed close to pcb.

[ivconic]

I will be interested in any results playing with "off resonance". I have tried quite a bit experimenting with that and never found a big jump in air distance. But experimenting carefully is difficult - everything must be very controlled and stable for each test. So maybe I missed a sweet spot.

Currently I'm of the opinion that we don't know why some TGSLs detect at 32 cm and others at 20 cm. Seems to be mostly the coil from what I hear, but no clear understanding why one coil bad another good. Even nulled the same but totally different I hear.

But don't give up is correct advice. We know some great TGSLs can be made. Someday maybe we can know exactly what is wrong and how to fix each one to be good. That to me is the holy grail of this thread.

It is a great game. Unfortunately I am on sidelines right now, cannot participate. I hope someday to resume experiments.

Have fun!

-SB

Correct; some TGSL's are working great and some don't, true. I made both kinds so far.
I am also wandering "in the dark" - not sure exactly what makes the difference. If i knew - i would tell you here for sure.
On every 4 good TGSL's i make one bad, that's the "rate".
I remember "CZ5" pcb version! Oooh! First of those worked (and still working) like no one else! Best ever! I made huge mistake and sold it at once. I should keep it for further investigations. Friend who bought it is working with it until today and he is very satisfied and happy.
Than i made second one. Bad!? I couldn't manage to find out what was the problem!? I changed coils, replaced many components...nothing. So i scraped it.
Than i draw "BD140" pcb version and success rate improved. I made ...maybe 10 handmades using that version and only one turned bad.
Always had enough coils to switch and compare. 90% cases was about the coil.
If coil is right and front end is correct..than signal losts are somewhere between gates and threshold stage, but where? I checked and measured almost everything there and found out no problems!?
TGSL is one tricky beast! (wouldn't be if i had more descent workshop with better measuring tools)
Because i had enough making coils for it i switched recently to SMW because now i can adapt it easilly for use with some original coils.
But i didn't gave up from Tesoro!
I intend to try to mod TGSL and adapt it for some original coils. Also i intend to make my first Lobo, because Lobo looks like more easy to be adapted for some original coils..

[simonbaker]

2 cents

I will be interested in any results playing with "off resonance". I have tried quite a bit experimenting with that and never found a big jump in air distance. But experimenting carefully is difficult - everything must be very controlled and stable for each test. So maybe I missed a sweet spot.

Currently I'm of the opinion that we don't know why some TGSLs detect at 32 cm and others at 20 cm. Seems to be mostly the coil from what I hear, but no clear understanding why one coil bad another good. Even nulled the same but totally different I hear.

But don't give up is correct advice. We know some great TGSLs can be made. Someday maybe we can know exactly what is wrong and how to fix each one to be good. That to me is the holy grail of this thread.

It is a great game. Unfortunately I am on sidelines right now, cannot participate. I hope someday to resume experiments.

Have fun!

-SB

[ivconic]

You're welcome ,

I hope anyone can use them for future use whenever there is something to make clear.
Those clips will stay there .
Whenever I get this 'thing' to work I will post the correct video's ( of a working TGS ) or I will make an online manual or something like that.

regards ,

Dennis the Mennis

That's the right spirit!
Ehh, if there were more people thinking like you!
Hopefully others will follow your example!
Regards!

[Dennis the Mennis]

Yes, this is what I meant.
It's Dennis' scope picture the one I posted...
Am I correct that the right nulling is achieved at position 0:11 of the first video that he published? (11 s after the start is the only way I can find to refer to that position... ), but that phase is anyway reversed in polarity...

Later on my photo- and video session I've changed the polarity off the rx coil so you are right , I've wanted to gain the pictures as posted on page 57.
I've made this photo for the voltage compare this was the lowest value I could reach , I was not really shure about the phase shift ...

regards

Dennis the Mennis

[Dennis the Mennis]

" ...Is there a possibility that when even the nulling seems fine , the sensitivity is poor ?..."

"Nulling seems fine" but you must understand that coils nulled well on one frequency are not nulled well on another (different) frequency. Residual voltage rised if frequency changed.

I think Qiaozhi already gave here good hint. Keep RX coil resonance within +1.8 - +2kHz than TX coil.
And use pp caps.

BTW thank You very much on your effort making those clips!
Best Regards!

You're welcome ,

I hope anyone can use them for future use whenever there is something to make clear.
Those clips will stay there .
Whenever I get this 'thing' to work I will post the correct video's ( of a working TGS ) or I will make an online manual or something like that.

regards ,

Dennis the Mennis

[Dennis the Mennis]

" ..Nulling on pin6 input LF353 (coil connected to pcb to compare with firdt video):
http://www.youtube.com/watch?v=AyK02Zk1PLY .."

I guess those "notches" (kind a distortion in sinus) are caused by bad quality of RX cap ?
Because i usually have there perfect sinus without any distortions...

I am using PP caps at TX and RX whenever i can find proper ones.

I will check this also , right now I've got so many caps I'm going to open my online second hand capacitor shop

regards

Dennis the Mennis

[Dennis the Mennis]

Darn, Qiaozhi. You beat me to it.

LTspice shows almost 3x increase in received signal voltage by changing to 15n, with a 6.53mH receiver coil.

Sorry about the wild goose chase, Dennis.

Never mind Porkluvr ,

I would never know what happened if I didn't change the caps ...
Perhaps it's a part of the solution , I'm going to try to tune the rx part.
If the sens increases as LTspice shows ...

regards Dennis the Mennis

[Dennis the Mennis]

I'm not going to say, "told you so".

Looking at the values for your coils and the tuning caps used, I have calculated your TX frequency to be 14.5KHz, which you have confirmed is correct. However, your RX circuit is tuned to 19.7KHz, which in my opinion is too high, as Tesoro circuits are usually off resonance by around 9%. In this case you should be using a calculated capacitor value of 15.5nF to tune the RX to 15.8KHz. I would suggest trying a 15nF cap instead of the 10nF and see if there is any improvement.

I totaly missed the part of 'off resonance , thanks for reminding me that .
I will experiment with the Rx part , I can remember that when I placed a 22 nF cap (somewhere around that value) in the Rx part a huge signal appeared compared to the 10nF but i chose for the 10 nF' because I've had the lowest residual voltage ...
I've learned this lesson

regards Dennis the Mennis