TESORO GOLDEN SABRE

[Qiaozhi]

Max - how about some photos of your TGS clone, both inside and out?

[Max]

Yes - I know all this.
What I'm asking about is what configuration has anyone used for either a DD or OO configuration with the Tesoro circuits. i.e. Did you connect one side of the RX coil to the screen within the search head, or perhaps used a centre-tapped RX coil, etc. ??
Also, did anyone notice any difference in operation if the RX coil is not connected to the screen within the search head?

No center tapped RX. I connected one lead of it just to the gnd wire used for tx coil.

[Qiaozhi]

Hi,
already explained by unregistered.

The connection I have is inside the coil. There the two shields wires leads are connected with an RX coil lead to provide a common gnd point there then that joint is connected to the gnd wire coming from the TX pads.

Right schematic is like in BandidoII that shows just RX coil without gnd connection at schematic. But connection exist in original coil made inside the coil itself, so one of RX wires coming from the search coil is actually connected to GND.

Think that as explained all this is to avoid twisted pair effects, having the common gnd connection just at the coils level.

I use that wiring in all my coils.

Kind regards,
Max

Hi Max,

Yes - I already know all this, no problem.
This is not what I'm asking.

My simple question is "When you made your DD and/or OO coils, did you also make a similar connection to 0V within the search head?".

[Qiaozhi]

No center tapped RX. I connected one lead of it just to the gnd wire used for tx coil.

Thanks - we both seem to be posting at the same time.

Have you tried leaving out the connection? If so, what was the result?

[Max]

Thanks - we both seem to be posting at the same time.

Have you tried leaving out the connection? If so, what was the result?

Hi,
sorry for latency... yes I have done too.

I leaved rx lead connected to the circuit without gnd connection in BandidoII test... (till now never tryed on Gsabre) seems it works too but not as well as when I connect to gnd. I think that most depends on nulling and offset of preamp.

Bad null and hi-offset preamp. could give problems. I haven't in Bandido any problem like saturations of first stages and the like but used gnd connection cause that way I gained more depth than without it.

Ivconic reported that his coils work better without gnd connection at rx: maybe depends on nulling cause he used a different method than the "standard" reading by scope, as you suggested me some time ago.

Of course rx leads must be connected in the right way... I mean with right phase of rx signal going to preamp. , otherwise disc works bad and also performances aren't good.

Best regards,
Max

[Qiaozhi]

Hi,
sorry for latency... yes I have done too.

I leaved rx lead connected to the circuit without gnd connection in BandidoII test... (till now never tryed on Gsabre) seems it works too but not as well as when I connect to gnd. I think that most depends on nulling and offset of preamp.

Bad null and hi-offset preamp. could give problems. I haven't in Bandido any problem like saturations of first stages and the like but used gnd connection cause that way I gained more depth than without it.

Ivconic reported that his coils work better without gnd connection at rx: maybe depends on nulling cause he used a different method than the "standard" reading by scope, as you suggested me some time ago.

Of course rx leads must be connected in the right way... I mean with right phase of rx signal going to preamp. , otherwise disc works bad and also performances aren't good.

Best regards,
Max

I've just carried out a few tests myself, and cannot so far find any difference if the 0V connection is made within the search head or not.
I intend to do some more scientific tests. More later...

[Max]

I've just carried out a few tests myself, and cannot so far find any difference if the 0V connection is made within the search head or not.
I intend to do some more scientific tests. More later...

Hi,
I've noticed the side effect of not having gnd connection at rx just on BandidoII, just there I've made such a test.
Maybe with such a small -V rail could be a problem having "propagation" due e.g. to offset along the amplifiers path ?

Anyway, my nulling on coil is everytime around 1mVpp... but there are also gain-to-offset effects to keep in mind... multiplication of problems!

Kind regards,
Max

[Qiaozhi]

Max - how about some photos of your TGS clone, both inside and out?

Hi Max,

Did you not see my previous post?

[Max]

Hi Max,

Did you not see my previous post?

Hi,
I saw it. My TGS-clone is still a prototype have just tryed a few in test garden.
I have too shame of my last creation that's why I don't post pictures of it...

I've used unconventional case for BandidoII... something you'll never imagine cause the board (1st Gary's design) is really large.

But I think using standard parts to pack TGS-clone... at now is in a rough state, I have few time to pack it well.

I mean... I can post pictures... but, cause of the shame, with same resolution of Esteban's schematics !

Anyway... it works... and BandidoII too... that's what important at the end.

Kind regards,
Max

[Esteban]

I mean... I can post pictures... but, cause of the shame, with same resolution of Esteban's schematics !

Oh!!! What important!!! The truth, the truth, you only teorize, no TB, no TGS, and others ask and ask the teacher, and in reality you have not finish nothing!

I want to see by your hands minimal resolution of schematics of your creation, OK for me!

Also, you put my name here in a thread I'm nothing to see, so I'll persecute you, chemist specialist in solvents and poisons! Frustrate chemist? Your leonine solution for a simple problem!!!

[Esteban]

Qiaozhi wrote:

Hi Max,

Did you not see my previous post?


Esteban respond:

No, Max don't!!!

Did you see the red tantalium capacitor? WHAT A DISCOVERY!!!

[Qiaozhi]

Hi,
I saw it. My TGS-clone is still a prototype have just tryed a few in test garden.
I have too shame of my last creation that's why I don't post pictures of it...

I've used unconventional case for BandidoII... something you'll never imagine cause the board (1st Gary's design) is really large.

But I think using standard parts to pack TGS-clone... at now is in a rough state, I have few time to pack it well.

I mean... I can post pictures... but, cause of the shame, with same resolution of Esteban's schematics !

Anyway... it works... and BandidoII too... that's what important at the end.

Kind regards,
Max

I'm not interested in the schematics, but I was interested to actually see a photo of your TGS. Anyway, you said earlier that your friends were so impressed that they all wanted one. So it thought it must be worth a look.
Also, how about some pics of the coils you have made, particularly the 12cm OO?

[Qiaozhi]

Qiaozhi wrote:

Hi Max,

Did you not see my previous post?


Esteban respond:

No, Max don't!!!

Did you see the red tantalium capacitor? WHAT A DISCOVERY!!!

Like a red rag to a bull!
Nice to see you here in the Tech Forum.

[J_Player]

I'm not interested in the schematics, but I was interested to actually see a photo of your TGS. Anyway, you said earlier that your friends were so impressed that they all wanted one. So it thought it must be worth a look.

Does it really exist?

[ivconic]

More pain for me....


I experimented a lot last few days with TGSL...Bad news is
that i was wrong about replacing LM308 with TL081!
TL081 is working but not that good as LM308?
First time i tried that, was in hurry so i havent noticed
differences. Now, when serious tests performed i am sure
that LM308 is hard to replace.....or...maybe there is good
way to replace it but TL081 is not best choice.
Earlier it was piece of cake to null coill and gain very good
results when LM308 was on pcb and device was used to null coil.
Now it is almost impossible to gain good results and null coil
when TL081 is put on pcb instead LM308??? I gain less distances on
nickel coin and sound is "broken" when reach detection limit..
I tried to achieve good results for over the 2 hours without
success...!? Everything else remained same except those 2 TL081...
I omitted those picofarads on 8. pin of LM308, of course,TL081
not need those...
So...feel like on begining again!?
Havent try to change values of surrounding caps and resistors...
Must be other way to achieve good results without LM308?
With a lot of help from my friends i prepared 4 types of pcbs for
TGSL....even one smd!
Other people draw those pcb's so i am not allowed to post those.
If original designers want to post their draws than let them do that.
I am not post neither one cose simply dont have right to do that...
There is 12x6cm TGSL onesided from my dear Dutch friend, 6x6 from one
Russian brother and small smd from another good friend of mine...
Also very nice coil housings in prepare...Soon to come and post photos
here...
On posted photo there are wounding bodies for two coil sizes;
one is for DD 190mm x 107mm and other 255mmx155mm...
I done some experiments using 0.20mm wire (0.22mm with varnish)..
Body 190mmx107mm;
130 turns=6.4mH =22ohms
125 turns=6.0mH =21ohms
123 turns=5.8mH =20.6ohms constrained=6.21mH
121 turns=5.72mH =20ohms
120 turns=5.57mH =20.1ohms gives frequency 14.9kHz
117 turns=5.38mH =19.6ohms constrained=5.73mH

Body 255mmx155mm;
95 turns=5.07mH=20.1ohms gives frequency 16.18kHz
Wire gauge affect inductance and frequency of course, so it is
obvious that i should use thicker wire to gain proper number of turns,
inductance and needed frequency. Wire should be 0.25mm to 0.28mm...
Since 16.18kHz is a way to high (we need 14kHz) i should wound more
turns, but it would raise resistance of coil to some 28-30 ohms...
Not good, so if i use thicker wire, all will come on right place.
Resistance will stay between 19-23ohms, inductance will be closer to
6-6.5mH and frequency will lower a bit, just arround 14kHz....
Problem is i left out of wire!? #$^@%^&^!!! I have to wait few days
to find proper one...
Only one problem left to be solved; LM308...It is not impossible to find it,
i can...But i am curious to find proper replacement...That's me!
Regards!