TESORO GOLDEN SABRE

[Max]

Hi,
Max.
I have experianced big nightmare!
Because I have similar problems with my first TGS,I used the same steps!
Cleaned well!And try to locate the source of the probleme!I have desolder again the LF358 then the sound stop!Afther this there is very week almost herable sound!With this IC off!Is this mean that my probleme is in batt checK?
Please help here.
I have played with 2N2222!Twist them in any posible way!Have changed all BC517,MPSA14;both 2N2222 no metter that they were brand new!
No point!But now I noticed that my BC517 is heating.But its fitted like on my first TGS.What the hell is goin on here?Cheking all day.Its look like there are no mistakes.Once I have managet to get some kind of reaction to hugh metal but now scream constant again and heating?How is this posible?
Thanks.
p.s.any new finds?

Hi,

have you checked for voltages ? what about negative rail ?

try to pull out the fet at battery checker to see if change something... maybe the problem is there.

But this will be a problem just if op amp there is going to zero at output... so if battery stay at around 8volts... and I think it isn't, right ?

Check fet terminals, if different from your previous too.

Let me know...

Kind regards,
Max

[tiktak]

Hi

Hi,
Ineresting.
We asumed here 14kHz for optimal!
So strange if TGS work fine in such wide area?
But what is best here?

[Molzar]

Tesoro 10.5" Coil

Lately obtained used Tesoro 10.5" inch concentric coil. Suppose to be land base coil, I see old Tesoro manuals offer this coil as accessoroy. Don't see it on their website anymore, only 10.5" for Tiger Shark. Could be same as Tiger Shark? operates at 12.5KHz. anybody know?

Hooked this baby up my TGS lastnight, with OK result ~28cm in air on 2cm silver coin.

Some instability in All Metal. Discrimination mode rock solid in max sense.

Did tests on coil specs today.

Tx = 23.51 ohms, 5.49 mH, Q = 1.47
Rx = 22.63 ohms, 6.19 mH, Q= 1.72

Will do more tests later....


Molzar

[tiktak]

Hi,

Hi,
Max.
I have experianced big nightmare!
Because I have similar problems with my first TGS,I used the same steps!
Cleaned well!And try to locate the source of the probleme!I have desolder again the LF358 then the sound stop!Afther this there is very week almost herable sound!With this IC off!Is this mean that my probleme is in batt checK?
Please help here.
I have played with 2N2222!Twist them in any posible way!Have changed all BC517,MPSA14;both 2N2222 no metter that they were brand new!
No point!But now I noticed that my BC517 is heating.But its fitted like on my first TGS.What the hell is goin on here?Cheking all day.Its look like there are no mistakes.Once I have managet to get some kind of reaction to hugh metal but now scream constant again and heating?How is this posible?
Thanks.
p.s.any new finds?

[tiktak]

Hi

Hi,
Ivconic.Max how are you?
I have just finish my next TGS.Better looking one.I have tryed some replacements.But have the same probleme as in begining.Constand loud scream.Maybe because I use MPSA14 now.Its louder.I have tryed to turn MPSA 14,nothing only some decriese in volume level.So it must be this 2n2222 again.I solder the pins like on my working device,but its look like this 2n2222 are different or I have other new probleme with same indications.
My PCB is not cleaned yet maybe this is the probleme but I dont think so.
Hope solve this soon.
And I will be able to post some good photos here.
Thanks

[tiktak]

HI,

Hi,
Dont wory.If the device is working fine than you have to make another coil!
Or try to match the capacitator at RX.
Be pasient and you will be there soon.
I have the same probleme.And solved it with my 3 coil.
Which coil did you make?22 or 27?
I adicve you to try first 22.Because the things are easyer.
See you soon.

[scevlik]

Hi,
Almost.
If you ask more people here they will tell you so but decide for your self what is the best way for you.
I null according Ivcoics advice.Disconect RX from TGS and conect to multimeter in ACV mode.
I achived this only with badmultimeter!You have scope................
So have no more to say here.
Null to 0.001 not to 0.000000000 there is no such!Only your instrument dont read it!But try this.
Good Luck

Hi

I nulled my coil but the results are same 18cm to 30mm coin,and very sensitive to motion.

[amtech2005]

TESORO GOLDEN SABRE

CAN YOU PUT A DUMMY LOAD IN PLACE OF THE SEARCH-COIL TO DETERMINE IF THE NOISE IS CREATED BY THE SEARCH COIL OR IF OSCILLATIONS ARE ORIGINATING ON GOLDEN SABRES CIRCUIT BOARD. CAN YOU USE A RESISTIVE LOAD FIRST , SET UP YOUR STAGES , THEN HOOK-UP A INDUCTIVE LOAD ????? TAKE CARE....................EUGENE

[tiktak]

Hi

Hi,
Ivconic and Max.
Very interesting talks here indeed!!!
I noticed that too!But haven't scope to check.And dont now for what to look.
Only think that I can say is that the coils with weeker audio are deeper!And loud are unstabile.I look for midle so far.

[ivconic]

Must be something about signal amplification in front end stage!? Not sure.
Waiting to get some scope and start measuring!

[Max]

By coincidence, yesterday, i realized something not clear to me yet!

Audio volume is directly dependable on coil specs.!?!?!?!?

Can anybody explain this to me? I am not fully awared yet what is going in TGS circuitry!

Yesterday i connected another experimental coil at my TGSL (i have one in workshop for testing) and audio was pretty loud! Almost unpleasant loud!
At once i switched that coil with some old and audio returns to pretty mum and weak!?!?!? Again new coil and audio - very loud!?!?
Heellll!??? What is going on here!?!?
After 20 and some device and 20 and some coils...just now i discovered that!?!?!?
I also noticed in the past some changes in audio volume with various coils, but changes were not so big...Just yesterday,with this new coil changes become very significant. Very,very loud audio!
Coil is nothing special. Ordinary coil. Smaller diammeter, arround 22cm...Wire used is 0.26-0.28mm...
Later yesterday turned that coil is not so good so i scraped it.
But question remained. What is going on here?
Main drawback on my TGSL-s so far was only weak audio. If somebody could elaborate this, i could solve even this last drawback.
What i think is that somehow audio strenght is directly dependable on some received signal amplitude...or something?
Or possibly on TX signal amplitude?
I did some measurements...yet havent spotted significant differences..???
Must be some value i havent measured yet? Some component from/to coil is related directly to audio? Not clear to me at all.
Pretty rough conclusion would be that 0.25mm wire and possibly thinner is most suitable for TGS. Wires over 0.25mm....for example 0.3mm i used mostly recently is provoking pretty good depth/disc/stabillity performances but weak audio!
Max...what do you think?

Hi,
I noticed just small changes not big on my coils. Then I noticed too something but I think we can explain thinking at how audio stage is driven by comparators: comparators action depends on voltage level on previous stages output in the chain.

If , for some reason, the average value of voltage due to a good target is higher than before we could spot the difference when on far target detection (cause on near detection audio stage will saturate easy in both cases... with old and new coil).

The reason or reasons... : I think we must investigate waveform at TX (e.g. any distortion could change averaged value by integrators on RX signal), sure this is just a theory cause I haven't tested that or noticed important differences in signal using my coils, watching stuff on the scope.

It's easy thinking that maybe if you use thick wire you could distort so much TX (so RX too) signal to change enough the integrated resulting value of "evenlopes"... giving maximum of this kind of behaviour when wave pass from sinus to near-square wave type (better say near-trapezoidal wave).

So my idea (or wild guess) is that your TX signal was distorted enough to change significantly the integrated value at each "evenlope" thus resulting in faster saturation of audio stage even on far targets.

This could be also related to magnetic effects of the new coil... like improved magnetic field strenght that depends on current flowing in the coil: if signal is trapezoidal instead of sinusoidal (with more area covered at each half wave)you'll get higher mean value of current, then higher field and chained flux too in same conditions e.g. same depth and target.

Kind regards,
Max

[ivconic]

By coincidence, yesterday, i realized something not clear to me yet!

Audio volume is directly dependable on coil specs.!?!?!?!?

Can anybody explain this to me? I am not fully awared yet what is going in TGS circuitry!

Yesterday i connected another experimental coil at my TGSL (i have one in workshop for testing) and audio was pretty loud! Almost unpleasant loud!
At once i switched that coil with some old and audio returns to pretty mum and weak!?!?!? Again new coil and audio - very loud!?!?
Heellll!??? What is going on here!?!?
After 20 and some device and 20 and some coils...just now i discovered that!?!?!?
I also noticed in the past some changes in audio volume with various coils, but changes were not so big...Just yesterday,with this new coil changes become very significant. Very,very loud audio!
Coil is nothing special. Ordinary coil. Smaller diammeter, arround 22cm...Wire used is 0.26-0.28mm...
Later yesterday turned that coil is not so good so i scraped it.
But question remained. What is going on here?
Main drawback on my TGSL-s so far was only weak audio. If somebody could elaborate this, i could solve even this last drawback.
What i think is that somehow audio strenght is directly dependable on some received signal amplitude...or something?
Or possibly on TX signal amplitude?
I did some measurements...yet havent spotted significant differences..???
Must be some value i havent measured yet? Some component from/to coil is related directly to audio? Not clear to me at all.
Pretty rough conclusion would be that 0.25mm wire and possibly thinner is most suitable for TGS. Wires over 0.25mm....for example 0.3mm i used mostly recently is provoking pretty good depth/disc/stabillity performances but weak audio!
Max...what do you think?

[Fred]

Hi
Once again,
I have achieved good nulling by connecting multimeter or scope at output
of 1st opamp.
Probably same results, but much easier to find lowest (relative) reading.
And no influence from instruments.
Fred.

[tiktak]

Hi

Hi,
Almost.
If you ask more people here they will tell you so but decide for your self what is the best way for you.
I null according Ivcoics advice.Disconect RX from TGS and conect to multimeter in ACV mode.
I achived this only with badmultimeter!You have scope................
So have no more to say here.
Null to 0.001 not to 0.000000000 there is no such!Only your instrument dont read it!But try this.
Good Luck

[scevlik]

Hi
I`m from Slovakia.
I have conected 1k resistor and 15nF cap to rx coil.Whit sliding RX coil on Tx i set minimal voltage on Rx coil.I have conected only scop. My multimeter show only 0.000v.
If I good understand it is the coil nulling.