TESORO GOLDEN SABRE

[Max]

Has or not contact to the negative battery pole clamp in RX coil?
According the schematics, in TGS Light - Not?, but in TGS - Yes?
What is true?
I readed contradictory opinions

Hi,
yes one lead of RX is connected to gnd: in standard tesoro's coils that happens inside the coil housing, then the wire from tx side at gnd potential is connected to shield and lead of rx inside housing. No matter of e.g. pcb tracks at rx about that: coils are this way.

So, you have to made it as in original coil.

Then some users reported also that detector works cool (or even better) without connecting RX lead to gnd: it's your choice doing thatway, but remember you need shield connected to gnd in any case to avoid capacitive problems, otherwise coil will be totally useless on soil.

Best regards,
Max

[Max]

".....between 12.4V and 7.47V...."

What are you saying here????

No matter if charged or fully discharged, 12v battery must show always 12 Volts!
If 12v battery showing less than nominal voltage that it is damaged and unuseable totally! Even if it is showing 11 volts - it is damaged...toss it through some window and put brand new one...
For example; my 12v/1.2Ah when fully charged is showing 13.8v...when fully discharged is showing 12.8 volts...obviously it is in good shape and useable.

Check your battery again. Check it disconnected from device and later check it connected to device. First device switched OFF than switch it ON during measuring...Than you can see eventual voltage drop. If it is droping bellow nominal voltage.....it is damaged....conclusion; toss it!
Regards!

Hi,
I think he mean something like NiCd battery pack: when batteries are really low on charge they can reduce voltage at leads to a fraction of volt. But if that happens I think he need charge better them or change for new batteries (sometimes damaged batteries last a few after charge).

If my idea is right he gets lot of voltage after charge withoud any load, so he thinks batteries are fully charged, then connecting to circuit the voltage accross drops too fast from top voltage and then that variation is detected as erratic bleeping at detector.

Often also battery holders are cause of problems: movements make contacts expose different resistance and thus giving erratic supply voltage with movements.

Kind regards,
Max

[ivconic]

Rdec4 yes make conntact to gnd but in coil, not at pcb. This is already explained earlier.

"..Often also battery holders are cause of problems: movements make contacts expose different resistance and thus giving erratic supply voltage with movements.."

Yes it is true! After a lot of troubles with various holders in the past ...finally i decided to solder batts. Eversince than i have no simillar problems.
But sometimes is pretty tricky when soldering batt. pins...

[Max]

Rdec4 yes make conntact to gnd but in coil, not at pcb. This is already explained earlier.

"..Often also battery holders are cause of problems: movements make contacts expose different resistance and thus giving erratic supply voltage with movements.."

Yes it is true! After a lot of troubles with various holders in the past ...finally i decided to solder batts. Eversince than i have no simillar problems.
But sometimes is pretty tricky when soldering batt. pins...

Hi,
I've done too a couple of times: used zinc chloride.
First I scratch surface with little piece of fine emery paper , then put over contact some small quantity (maybe 10mg) of zinc chloride paste that's kind of old flux stuff for big solderings works like soldering metallic parts... then use a 60-100W soldering iron to heat up that thing and add some small quantity of solder-alloy (lead-tin one).

You can do similar even without zinc chloride... but just scraping surface: the rosin cored wire will polish metal enough to make good solder joint.

Only care will be put on timing the soldering operation: I do everything in max 3-4 seconds to avoid damaging cells by heat.

Best regards,
Max

[erolunall]

Hello Friends

There are one diference with schema and Pcb of TGS. There are 1 more 1n4148 diyot on schema near lm308 paralel with 1M and 22n but not shown PCB parts replacement.it is important or not ?
Regards
Erol Ünal

[Max]

Hello Friends

There are one diference with schema and Pcb of TGS. There are 1 more 1n4148 diyot on schema near lm308 paralel with 1M and 22n but not shown PCB parts replacement.it is important or not ?
Regards
Erol Ünal

Hi Erol,
thanks for that information: I've missed that diode at all !

Now it's about clear that first PCB hasn't it as I've indicated in picture: the upper LM308 hasn't any diode there, instead the lower has it as in schematics (where is the arrow).

I think this fact could explain why there are sometimes noticeable differences between TGS and TGSL.

The function of diode there is limiting dinamic range of op amp. This fact could be strongly related to instability in TGSL... but I think topic need some more investigations.

Anyway, it's absence seems is not a problem on TGS: I haven't it on board just like PCB picture and everything works cool.

Best regards,
Max

[rdec4]

Max, ivconic,

Thank you to the help and the information.
Now, I have other question:
What is the right value for C7 capacitor? and what is its role?
Please, excuse me, if you are already discussed it.

[Max]

Max, ivconic,

Thank you to the help and the information.
Now, I have other question:
What is the right value for C7 capacitor? and what is its role?
Please, excuse me, if you are already discussed it.

Hi,
well... we need a picture of an original TGS to say that. In some other schematics it's 5pF there. So maybe that's right value. I've mantained it at 10pf cause noticed that detectors works cool with that value.

I think that original was 5pF... but change a few if you have 10pF there.

So it's your choice using one value or another.

Kind regards,
Max

[Unregistered]

TGS

For MAX
Ref: TGS (28DD coil)




I report you which the coil wound whith 26ohm TX and 27.5 ohm RX.
I bought a new NICAD battery and change the capacitor 100pf by 220pf (near LM 353)….now it is functional, but very, very very
sensible. When it is stopped on the table no audio signals, but a finger soft touch on table, cable, box, pole or coil produce a short
sequence of BIPS. Is it normal ?

What the best solution for it?
Regards


DIRCEU

[tiktak]

Hi,

Same thing. Use negative of battery as reference or GND tracks/pads on PCB... they are (about) at same potential.

Hi,
Max.
I have finished one coil with not so good performance,but now I havent much time............
So only the most inportant:When I null with multimeter from LF353 pin7 should I conect 1k resistor and 15 N capacitator?
Because I null without anything.The coil is not so good and I get many falses sometime horible.....But I think that soon will have good machine...
I still cant reach 35 cm ...
I make a coil according your pictures and cant fit it in the original housing that Ivconic is talking about?I will check my datas again,but..
Can this coil be with 255X137 former size?
Thanks

[tiktak]

Hi

Hi,
Ivconic wanna ask you on what kind of terain did you find those 250 roman coins.Did you prospect near mounin fortres?Or?
How were this coins been located?I mean one here one there?Ore you digg a how and begin detecting cm buy cm?
Most of the terains that I go on are rocky hills and detecting there is realy hard!Because on surfice there are stones and detector cant be keept close to ground.
I think that TGS can detect coin at 30cm in a prepared for seeding field because of the lightness of the soil,but on terains like in my case I think that it cant penetrate more than 18cm?
Also when I test it I detect some iron pieces that should be discriminated!But all ithems were on the surfice below the old leaves.Maybe my coil is not so good?
And I were buisy with babysiting my friend............
but next time I will detect like I should.

About this OO coil,you have made several why you give up?
They should be better!

Or like I say before,I saw one detector that have 40 cm I think that its DD coil and it were able to detect single coin around 60 cm in AIR!

Have you tryed to make 40 cm coil?How many turns must be done?
So, 220X400 DD coil...........
TX=
RX=
Thanks

When I add 10 ohm resistor in series with 8 ohm speaker the fals signals were reduced.And behaviour is much better.
Now I will cange this 2k2 with 8k7 to see the diferance.

[Max]

For MAX
Ref: TGS (28DD coil)




I report you which the coil wound whith 26ohm TX and 27.5 ohm RX.
I bought a new NICAD battery and change the capacitor 100pf by 220pf (near LM 353)….now it is functional, but very, very very
sensible. When it is stopped on the table no audio signals, but a finger soft touch on table, cable, box, pole or coil produce a short
sequence of BIPS. Is it normal ?

What the best solution for it?
Regards


DIRCEU

Hi Dirceu,
about cap of 220pf: could be good there even if right value (from Tesoro) is maybe 5pF...so much lower. Happens often that changing values there you can tune much better.

About noise when you touch table or wire etc... what about your coil assembly ? I mean do you use epoxy to seal/fix coils inside housing ?

Small relative coil movements can give the behaviour you wrote about.

It's not normal you hear that beeps when move coil or table where coil is ...not good. If you fixed coils well with epoxy or other rigid stuff then problem could be related to metals in the table or movements of e.g. pole (metallic) that is detected by coil... it's mechanical problem you have to reduce/solve... otherwise cannot use detector on the field.

Kind regards,
Max

[Max]

Hi,
Max.
I have finished one coil with not so good performance,but now I havent much time............
So only the most inportant:When I null with multimeter from LF353 pin7 should I conect 1k resistor and 15 N capacitator?
Because I null without anything.The coil is not so good and I get many falses sometime horible.....But I think that soon will have good machine...
I still cant reach 35 cm ...
I make a coil according your pictures and cant fit it in the original housing that Ivconic is talking about?I will check my datas again,but..
Can this coil be with 255X137 former size?
Thanks

Hi,
you don't need cap and resistance when use preamp: cause you connect coil to rx preamp there are already the cap (15nF) and resistances (two braches of op amp) there on LF353. So you have just to find minimum voltage at pin 7.

About my picture... you have to consider that I haven't the bulgarian housing like you and Ivconic... so my former is related to pictures Ivconic posted here... and there is some approximation, but only few geometry I mean (maybe some millimeters). Other stuff is perfect: inductances and resistances (even frequency of oscillation at tx) match exactly with Ivconic's data.

Best regards,
Max

[Max]

Hi,
Ivconic wanna ask you on what kind of terain did you find those 250 roman coins.Did you prospect near mounin fortres?Or?
How were this coins been located?I mean one here one there?Ore you digg a how and begin detecting cm buy cm?
Most of the terains that I go on are rocky hills and detecting there is realy hard!Because on surfice there are stones and detector cant be keept close to ground.
I think that TGS can detect coin at 30cm in a prepared for seeding field because of the lightness of the soil,but on terains like in my case I think that it cant penetrate more than 18cm?
Also when I test it I detect some iron pieces that should be discriminated!But all ithems were on the surfice below the old leaves.Maybe my coil is not so good?
And I were buisy with babysiting my friend............
but next time I will detect like I should.

About this OO coil,you have made several why you give up?
They should be better!

Or like I say before,I saw one detector that have 40 cm I think that its DD coil and it were able to detect single coin around 60 cm in AIR!

Have you tryed to make 40 cm coil?How many turns must be done?
So, 220X400 DD coil...........
TX=
RX=
Thanks

When I add 10 ohm resistor in series with 8 ohm speaker the fals signals were reduced.And behaviour is much better.
Now I will cange this 2k2 with 8k7 to see the diferance.

Hi,
i think our dear friend Ivconic will not post on this forum again for a while... too many problems with some stupid people.

I can partially answer your questions:

About mountain and rocks: you are right ... detectors like flat soil, is not great news.... some people prefer using 2-boxes or PI in those places... cause VLFs are not easy to use and lose depth in such terrains. All true, but if use PI you lose discrimination; if use 2-boxes you cannot find single e.g. coin but just jars full of them (well you need enormous luck to do really) cause they are not sensitive to smaller items. Then VLFs are still good for mountains: my opinion is that they are ALWAYS better (beach-hunting and e.g. australian-goldfields apart).
Better losing 10cm depth but saving discrimination and finding even smaller stuff.

About iron detection under leaves...well it's normal: huge iron parts will distorce field and then detector will sound at such small distance of few cms from iron target. But from longer distance you cannot detect them, right ? That's why disc is so important... if it's iron and sound you can find without digging but just moving leaves, isn't that way ?
Then disc will cancel out all small iron trash (nails, rusty wires etc etc).

OO coils are not good for your soil conditions, that's why Ivconic maybe don't waste more time doing them...and make instead large DDs.

A 40cm diameter coil will be a monster of sens on TGS... but you have to consider that will pick-up much soil effect so you need perfect balance to deal with one of these.

Last: detecting a coin at 60cm on air is not like on soil... you can do with e.g. a 3cm diameter coin, a 10-11'' fast monocoil and a very sensitive PI... but then... try to use it on real soil ! Impossible in most cases...

On the beach will be a real monster but on inland sites...wow man... better using eyes... too many falses. Try to belive.

Kind regards,
Max

[kt315]

folk, I did not find up this question but I still remember, it was about -V source and there was a problem with low value of -V.
I offer to change a part of the schematic according to this picture.