TESORO GOLDEN SABRE

[Max]

Max, thank you for hints. I’l will check all as you sugested.
Speaking about coil, I quite sure that i tight wire good with cotton cord. Maybe my former is’nt good. I suspect on circumference of D shape is not good? It is around 66cm?

For audio you have, basically, two choices
use a 2K2 resistor instead of 33K at last LM358 will rise up audio easy, but more instability could be the price

2k2 is already there and no instability at all because of veak sensitivity,

-use the 1Mohm resistor at D12 like Ivconic showed in schematic of TGSL, with the switch I mean: same thing, strongest audio from far targets too but you'll have some instability more

There is no differene’s if I put 1M resistor or not. Without 1M, TGS have behavior like a there is 1M resistor. Will see when I check once more all of capacitors and semi’s in osc section.

Best regards,
Darko

Hi,
my circumference of nails pattern is exactly 64.5cm.

If using 1M resistor is all about the same you probably have some bad thing before comparators... could be some IC like TL081 or the like... cause I noticed a huge difference when 1M is in the circuit:

comparators saturate at minimum signal , even from far and very weak from small targets... where with just diode it isn't... and I get a very small audio response like tic-tic from speaker... not a good and loud tone.

With just diode the response is progressive... nearest the target, louder the response; with 1M instead is a totally flat response, always loud... independently by target size or distance...so kind of real comparator action (with very sharp rise/fall edges).... also you can understand if target is far or near just hearing the sound lasting less or more, but not about intensity that's always the same.

Check the LM308s part before comparators... also try different ICs there.

Best regards,
Max

[Max]

This is tru.
When you setup GEB on the field, TGS works great.
I had the same problem, but on the beach with black sand, after i tried a few GEB settings, i got good ground balance.
Now my question is if is possible to use a smaller variable resistance on GEB. This because setting it on the rigth point was a little difficult, while the pot has a very narrow way to reach the correct setting.
Also, what about setting GEB has an external control on TGS?
Regards
Nelson

Hi Nelson,
yes we can try with an external pot... but problem is that resolution of normal 3/4 turn pots is that you cannot move easy between narrow small resistance values... very difficault.

Solution could be a multiturn pot there from 3 1/2 turns to 10 will be ok I think. Then one must perform that setting each time using all-metal mode. In bandidoII geb is that way: 3 1/2 turns pot wirewound.

The fact GEB is so critical sometimes is related to different soils... that's why in bandido and others there is an external geb pot.

I haven't tested yet but I'd like to do... cause could be positive for a better stabilization from one soil to another.

Kind regards,
Max

[Fred]

Hi,
The Zener diode is also very important for frequency,you should check its value and polarity.
Fred.

[Darko]

Max, thank you for hints. I’l will check all as you sugested.
Speaking about coil, I quite sure that i tight wire good with cotton cord. Maybe my former is’nt good. I suspect on circumference of D shape is not good? It is around 66cm?

For audio you have, basically, two choices
use a 2K2 resistor instead of 33K at last LM358 will rise up audio easy, but more instability could be the price

2k2 is already there and no instability at all because of veak sensitivity,

-use the 1Mohm resistor at D12 like Ivconic showed in schematic of TGSL, with the switch I mean: same thing, strongest audio from far targets too but you'll have some instability more

There is no differene’s if I put 1M resistor or not. Without 1M, TGS have behavior like a there is 1M resistor. Will see when I check once more all of capacitors and semi’s in osc section.

Best regards,
Darko

[nelson]

This is tru.
When you setup GEB on the field, TGS works great.
I had the same problem, but on the beach with black sand, after i tried a few GEB settings, i got good ground balance.
Now my question is if is possible to use a smaller variable resistance on GEB. This because setting it on the rigth point was a little difficult, while the pot has a very narrow way to reach the correct setting.
Also, what about setting GEB has an external control on TGS?
Regards
Nelson

You dont need to move Disc. pot to reject ceramics at TGS. You can adjust it with GEB trimmer to void ceramics,hot rocks and simillar. But you have to take it there and adjust it at that moment under those conditions...It will work just fine....of course you must make good coil...DD coil!
Regards!

[Max]

When I turn my TGS on, while batt check audio tone is loud enough, but when batt test ends, audio going to be very weak in normal operation. Some short time everything was been ok but then difference between tone loudness in batt test and working mode now has very big. Coil is 255x137 ivconic data, on former Max posted here, but TX freq is 15,30????I’m sure that wire diameter is 0.25 without varnish. What should be I check first? Voltages seems to be ok. +8V and -6,12V. Please help. My English is too bad to explain better. [/font]

Hi Darko,
the battery checker is always loud cause the op. amp. that battery checker use gives a strong commutation when batt is ok... so it's normal it is very loud.

When it stops the fet at battery checker "open" circuit from it to output so your output depends then just of output of signal path amplifier (comparators) that drive the last LM358 half connected to audio stage.

Voltages are ok: +8 , -6.2 are fine. If you used Ivconic's data also coil must be ok.

Your frequency is no good... good operations are under 15KHz... with data provided you must gain min. 14.6 to 14.8 Khz maximum.

About coil you need tightning wire with rubber or plastic adesive tape or a cotton cord... and the like... cause if not tight you get bigger frequency from it.

That's could be a problem cause of some capacitance reactance at that higher frequency in the circuit , so stay under 15KHz, possibly under 14.75Khz.

So I suggest you check coil again and oscillator section, cap values, zener diode etc... you must reach something around 14.7KHz first of all.... then you'll focus on optimization. Of course, that will be with shield too, that you always need for real use on soil.

Audio is always weak at good GEB setting: this is an original drawback of TGS... so you have to make some mod to gain better.

For audio you have, basically, two choices :
- use a 2K2 resistor instead of 33K at last LM358 will rise up audio easy, but more instability could be the price
- use the 1Mohm resistor at D12 like Ivconic showed in schematic of TGSL, with the switch I mean: same thing, strongest audio from far targets too but you'll have some instability more

Or both things... if your instability level is low enough to leave you in conditions of using detector on real soil.

Then using headphones is always better: you don't lose even smaller sounds with them... where instead using speaker you can lose much of them.

Kind regards,
Max

[Darko]

When I turn my TGS on, while batt check audio tone is loud enough, but when batt test ends, audio going to be very weak in normal operation. Some short time everything was been ok but then difference between tone loudness in batt test and working mode now has very big. Coil is 255x137 ivconic data, on former Max posted here, but TX freq is 15,30????I’m sure that wire diameter is 0.25 without varnish. What should be I check first? Voltages seems to be ok. +8V and -6,12V. Please help. My English is too bad to explain better.

[Geo]

Hi Ivica. Thanks for info
I will arrive at 2 Nov morning.
My regards

[ivconic]

Hi Ivica.

How is the weather at Beograd?????
Regards

Dont really know for sure? Here at my place rains,rains,rains....Today a bit better. But you have luck Geo, it is getting bettter. On November the 2. will be sunny an shinny! Wish you nice trip!
Regards!

[Max]

Hi guys. I just wanna say that you just got another freshman on coledge. I hope that I aint gonna bug you around real hard with very stupid things like someones in the past- maybe just a bit less. :-) Well I was here on this forum for a couple days, read several pages and as reading your posts something snap in my head: I must join these guys in building Tesoro, and stop looking it from side.
Yesterday i built a pcb in a few hours, but cant get all of the components at once. So, its gonna be a loooong week.

ONCE AGAIN HI TO EVERYBODY IN HERE!!!

I have 1 question, anybody: is there a diference betwen using BF245c and J107, and what is it?
Pozdrav za sve nase!

Hi,
don't know about J107 but BF245 a,b and also c are good for TGS... then you can use also other fets too. As Geo stated they could have different cutoff voltage and there is about all the difference from one to another cause other stuff like Rds resistance is always low in signal type fets so 100 or 50ohm don't make great differences on these designs. On TGS this is also more true cause circuit is not critical at all... it will always work also with not original parts but similar.

My only advices about components are on ICs:
try to find LF353 for preamp (or use TL072/TL082 instead if you can't)
try to find LM308s (or use TL071/TL081)
try to find a good dual op. amp low noise instead of TL062 (use LF442 or better some TLC2262)
try to find one LM393AN for last comparator

Other stuff like transistor, diodes, caps etc you can vary as you want about type (not value of course) and circuit will be fine. For best tuning use scope to track signals from start... look for ringing and other noise... try to reduce them.

For coil use Ivconic's data (255x137mm TX=100 RX=105 wire 30AWG)

Best regards,
Max

[Geo]

Hi Ivica.
How is the weather at Beograd?????
Regards

[Geo]

Hi guys. I just wanna say that you just got another freshman on coledge. I hope that I aint gonna bug you around real hard with very stupid things like someones in the past- maybe just a bit less. :-) Well I was here on this forum for a couple days, read several pages and as reading your posts something snap in my head: I must join these guys in building Tesoro, and stop looking it from side.
Yesterday i built a pcb in a few hours, but cant get all of the components at once. So, its gonna be a loooong week.

ONCE AGAIN HI TO EVERYBODY IN HERE!!!

I have 1 question, anybody: is there a diference betwen using BF245c and J107, and what is it?
Pozdrav za sve nase!

Yes. At cut-off voltage. Use for better BF245A or B. I used at TGS all the fets without any difference(generally), but i think that in fine tuning the BF245B will work better.

[gagi_pirot]

HA HA :-) DONT FALL ON THAT I WAS JUST JOKING. C U ALL VERRY SOON

[gagi_pirot]

beginer

Hi guys. I just wanna say that you just got another freshman on coledge. I hope that I aint gonna bug you around real hard with very stupid things like someones in the past- maybe just a bit less. :-) Well I was here on this forum for a couple days, read several pages and as reading your posts something snap in my head: I must join these guys in building Tesoro, and stop looking it from side.
Yesterday i built a pcb in a few hours, but cant get all of the components at once. So, its gonna be a loooong week.

ONCE AGAIN HI TO EVERYBODY IN HERE!!!

I have 1 question, anybody: is there a diference betwen using BF245c and J107, and what is it?
Pozdrav za sve nase!

[ivconic]

No. I havent finished Vladimir's pcb yet. I put few components on it ad left it somewhere in a pile of pcb's.Nice pcb, small...Now i have 8 Goldy's already finished waiting to be packed in housings. So i am doing one by one these days. Goldy pcb (1. version) is working very good.I have no complaints. Try it. These days all things going very slow here,at my place. I have a lot of other things to do....that's why am a bit lazy and tired to spend less time in workshop. Last 10 days was raining like from the bucket! Damn rain! Tomorrow and day after tomorrow should be better, so i was hoping to go outdoor, on the field...We'll see.