TESORO GOLDEN SABRE

[Fred]

Hi Max,
Thanks for your comments,
Yes i will build a good DD coil, i already had made some experiments with it but as i lack a good housing i prefered to make a smaller one that i could actually finish - even if performances are not so good.
I have noticed also that with a badly nulled coil sens pot make almost no difference.
I was able to achieve a nulling of less than 50mv at output of opamp before shielding, but after i put the shields it was not so good.And in the next one i will folow your advice about overlaping.But with that form it was no easy.
Best regards!,
good luck to all builders
Fred.

[Max]

Hi Max,
Can be used a 45cm coil for IB md ???

Regards!

Hi,
DD ? of course... but you'll get much more ground effect signal from it.

A very large coil will give you better performances on detecting great things like in the cache test... so small boxes ...cups and the like. You could have problems detecting very small things e.g. 1cm diameter stuff with it. I can detect 1cm coins with the 255x137mm (that's 10'' DD coil) but I'll wonder if TGS could detect the same small thing with such big coil of 45cm, more than 17'' diameter. But then that depends also on flux line shape so maybe different arrangements could give different results on smaller things.

Then you have also consider that nulling could be a bit difficault too... then you need for sure an external GEB pot to balance on real soil.

Best regards,
Max

PS: an example of vlf-like machine with big coil is the relic-hawk from minelab... ok ok... it's not just a plain VLF like we think about cause of ML addiction to harmonics etc... but it's IB-T/R-VLF about tx frequency and coil.
COIL I MEAN IS 15'' round DD

[1843]

Hi Max,
Can be used a 45cm coil for IB md ???

Regards!

[Max]

Hi Max, Fred, Ivconic….
Once more I searched PCB for errors and found that 100k trimpot in GEB section has no resistance. Maybe this can explain strange behavior of audio section in past? I replaced him and now TGS works better but sensitivity remained 20cm. I changed already LM308 with new ones and instead TL062 I place LF442 one and after that sensitivity become a bit better. I noticed in the meantime that a sensitivity control has no influence at machine. No difference with sensitivity pot turned at 1 or 10. No changes. I know that right now I don’t have coil in which I can swear is nulled properly but in the past with this same coil gained much better performance. I start to suspect that my PCB isn’t good, etching in hurry etc. Now, maybe I pay tribute for my impatience. I think maybe is time for me to give up from TGS for now and try Goldy or Vladimir’s PCB and then with this experience back to TGS again.


Regards,
Darko

Hi,
if sens pot have no effect on your TGS there is some mistake... maybe in coil. When things are right it gives maximum sens at max position but when at minimum you can always detect stuff but at lower range. I think that is a regulation say from 70% to 100% of total...so just on 30% of sens regulation starting about from 70.

But that may change from one homemade to another cause of tollerances of components... and coils.

If coil is no good or you have problems at preamp and the like I think you couldn't notice that behaviour cause maybe your detector sound when signal is already strong (near target)... then you are already under 70% of theoric range... thus giving no variations.

If it isn't coil:
you have to check the signal path... if preamp is ok you'll focus on fets and then 308s (or other ics there)... and then on comparators after the sens pot.

All parts can give that problem if there is a mistake or wrong stuff/values: an example are fets ... you can use different kind even various versions of the same device like BF245A,B or C but there are differences about cutoff voltages... then your devices could work bad if not compatible with TGS sampling voltages commands at gates.

The original fet TIS75 has e.g. min VGSoff -0.8V and max -4V ; but the BF245 has min -0.5 to max -8V that's a huge difference.

If you consider the worse case you need really -8V to switch off them then you'll get into troubles cause maximum negative voltage for TGS is -6.2V and command line of fets don't reach that value but something less around -6V.

So... your fets, in the worse case, could remain partially closed... that's why is so important having a scope in that measures: you can see if e.g. sampler part works ok or not. For other parts is the same... looking at signals is much more efficient way of finding mistakes in circuits.

Best regards,
Max

[Darko]

Hi Max, Fred, Ivconic….
Once more I searched PCB for errors and found that 100k trimpot in GEB section has no resistance. Maybe this can explain strange behavior of audio section in past? I replaced him and now TGS works better but sensitivity remained 20cm. I changed already LM308 with new ones and instead TL062 I place LF442 one and after that sensitivity become a bit better. I noticed in the meantime that a sensitivity control has no influence at machine. No difference with sensitivity pot turned at 1 or 10. No changes. I know that right now I don’t have coil in which I can swear is nulled properly but in the past with this same coil gained much better performance. I start to suspect that my PCB isn’t good, etching in hurry etc. Now, maybe I pay tribute for my impatience. I think maybe is time for me to give up from TGS for now and try Goldy or Vladimir’s PCB and then with this experience back to TGS again.


Regards,
Darko

[Max]

Hi,
Here i post some pics of my TGS : i hope they can be usefull .The coil form is from a CRT monitor support, excellent as very strong, but a bit too small: diameter of the coil is only 22cm.With this coil i could get 25cm for 1 euro coin,same foir similar size of gold, and around 30cm for a big copper coin.
I will try to improve it a little and build a bigger coils, will post eventals (good) results
Happy building,
Fred.

Hi Fred,
you have to try Ivconic's design of DD coil to gain better sens. If you results are good with an smaller coil you'll be surprised with the large one.
Look at other posts, follow numbers and you'll end up with a very good thing at the price of some wire and a bit of patience.

About overlaps I noticed your coil is heavy overlapped and round shaped in central area: I noticed that the best way is keeping wounds about parallel at middle, like you can see opening a coiltek's one (the ones used in minelabs).

I suggest you make a big one and null very carefully... then you'll be surprised.

Kind regards,
Max

[Fred]

Hi,
Here i post some pics of my TGS : i hope they can be usefull .The coil form is from a CRT monitor support, excellent as very strong, but a bit too small: diameter of the coil is only 22cm.With this coil i could get 25cm for 1 euro coin,same foir similar size of gold, and around 30cm for a big copper coin.
I will try to improve it a little and build a bigger coils, will post eventals (good) results
Happy building,
Fred.

[detectoman]

max:
thanks very much, for your help whit links on oscilloscope for my
this machine oscope, tektronics, dual canal, two chanels, is of great brand, traces are very clear and is very resistan to excess
soon i send photo of this
best regards in your finds, one soda drink for you
best detectoristman detectoman jejejejejee

[detectoman]

hello quiozhi

Hi Detectoman,

I'm not sure what you said - but it's a good avatar, don't you think?
Yes - looks like SuperMan's cousin. You can use it like this
hello quiozhi:

thanks for your help, but, i am looking for, one avatar may be one photo of my finds, eg,eg coins early years, 56,a,j , may be, or one project my on detector build for my
soon i can repair my digital camera for shot picture desire
thanks friend for you interes, in these subject
and apologies for my bad english heheheee

best regards in your hunt treasure
fiuuuuuuuuuuuuuuuuuuuuuu
detectoman

Elie

ahhhhhhhh ok very good, this day ohhhhh,
but.....
........ how i drive this stuff..buaaaaaaaaaaaaaaaaaaaaaaa
ok relax relax little move whitout riskkkkkkkkkkk... burn
mammmmmmmmmmm
thanks

I think Elie was on top of detectoman today on bed, oh what an expressions

[Max]

ahhhhhhhh ok very good, this day i have one oscilloscope, ohhhhh,
but.....
........ how i drive this stuff...??????? panel is some control instuments of cabine of transborder spacial columbus
buaaaaaaaaaaaaaaaaaaaaaaa
ok relax relax little tecnic
say me what i can t move whitout riskkkkkkkkkkk of short burn circuit???????
mammmmmmmmmmm
thanks detectoman

Hi detectoman,
thanks for greetings I wanna reply with mine too.

About scope you can find informations in spanish on oscilloscope (general) at:

http://es.wikipedia.org/wiki/Osciloscopio

and a small but good tutorial (in spanish too) on the hameg's website at:

http://www.hameg.es/osc/osc.htm

that's more than enoygh to start understanding how it works and how you can use it.

It's a really powerful instrument if you can use it right... and so I think you'll be fine after a while using it with success.

Enjoy !

Kind regards,
Max

[ivconic]

Max, i reduced weight of my TGSL to 2.2kg...

I dont know...? I do not bother myself with device complexity, never. Usually main reason to build or not to build some device is if i have good pcb for it or not.... If i had pcb draws i would make any good detector by now....My main problem are pcb's and (eventually) som rare component, hard to find in shops....
Lobo...? If pcb draw exist for it...i will make it for sure...Long winter here in mountains....nothing to do
Usually i am hyperactive, i dont sit at home 4-5 hours daily...but now...damn rain!
Max... i'll send you pm now...
Regards!

[Qiaozhi]

qiaozhi

gulp
who is these?
where you sacastes ese, mira pues, is brother of superman? edition european
ohh nouuuuuu
i am very beauty what this
un abrazo para usted qui----- fiuuuuuuuuuuuuuuuuuu
detectoman, the detectorist non plus

Hi Detectoman,

I'm not sure what you said - but it's a good avatar, don't you think?
Yes - looks like SuperMan's cousin. You can use it like this ->

[detectoman]

ahhhhhhhh ok very good, this day i have one oscilloscope, ohhhhh,
but.....
........ how i drive this stuff...??????? panel is some control instuments of cabine of transborder spacial columbus
buaaaaaaaaaaaaaaaaaaaaaaa
ok relax relax little tecnic
say me what i can t move whitout riskkkkkkkkkkk of short burn circuit???????
mammmmmmmmmmm
thanks detectoman

[detectoman]

qiaozhi

gulp
who is these?
where you sacastes ese, mira pues, is brother of superman? edition european
ohh nouuuuuu
i am very beauty what this
un abrazo para usted qui----- fiuuuuuuuuuuuuuuuuuu
detectoman, the detectorist non plus