TESORO GOLDEN SABRE

[Max]

Yes ivconic, you are right in that way, but my problem with TGS was't nulling but sleepy LM308AN, both of them, just as Max sugested to check them and replace. I don't have problem with nulling at all! I nuling using AudioTester Osci even i knew you disagree with this way of nulling. I think, software like is Audio Tester is good enough for nulling coils and trick is only in proper calibration of these. I order pair of LM308H in metalic case like as you sugested here and I'm sure TGS will work great, just like before i burn it! Anyway, thank you for sugestions and help. About my unimeter,I'll just readjust him and will be good until i buy new one. Then i will try hammer on it.
Regards,
Darko

Hi,
the important is , at the end, that you are satisfied of your work with TGS ! So have few meaning if use one tool or another... everything is good if you can reach objective... that seems a Machiavelli's phrase but is plain truth about electronics DIY projects.

And seems you are near solving of other small problems: very good.

Let me know about how things go on with your detector... if there are some other problems or if you need some advices... that's why this forum exist.

I'm sure Ivconic and other people will give their help too and common brainstorming could make our experience with TGS more and more enjoyable.

Best regards,
Max

[Max]

Hi all,
here is a website with a project like I mean for people having problems reading small voltage values using bad meters:

http://sound.westhost.com/project16.htm

Of course, maximum resolution seems limited to 3mV but it's not bad considering that a few of real multimeters can gain such a precision on the e.g. 200mV scale for signals of 10-15KHz frequency.

So take a look... I've also others (somewhere) printed stuff but cannot find at the moment so posted that reference to the website of above.

The meter circuit is like in the picture ... one op. amp... some diodes ... all easy stuff.
If you wanna do even better use some more discrete components, fet etc...picture below.

The complete project require another part (attenuator) but for nulling coils it can be omitted just limiting readings in the lower range only.

If you haven't a scope or a very good multimeter I suggest you think at it as an alternative for nulling coils.

Best regards,
Max

[Darko]

Hi,
the important is , at the end, that you are satisfied of your work with TGS ! So have few meaning if use one tool or another... everything is good if you can reach objective... that seems a Machiavelli's phrase but is plain truth about electronics DIY projects.

And seems you are near solving of other small problems: very good.

Let me know about how things go on with your detector... if there are some other problems or if you need some advices... that's why this forum exist.

I'm sure Ivconic and other people will give their help too and common brainstorming could make our experience with TGS more and more enjoyable.

Best regards,
Max

Thank you Max for helping me. Also others here willing to help. Ivconic was help me so many times about Cl3 and now with TGS and always when is too hard for me to explain problem in english i call him at home and borring him, and strangle him and hi always with patience listen to me and trying to help. I'm just hobbyst and try to learn more about electronics. And building such project like TGS for me is really challenge, especially if machine will work ok for me. I'm not trying to become expert, just learn some more, so, expensive gadgets, osciloscopes etc is not for me. I will tray to make one milivoltmeter from schematic ivconic posted here earlier or from this one you post here. When I replace 308s will see how TGS works with and post here my impression. Maybe this will help someone like me who just likes to play with electronic staf and on the way learn something more.Thanks all.
Best regards,
Darko.

[Fred]

I dont want to insist but there is no point in making a mv-meter if there is already one on the board, and (supposely)tuned to the right frequency:just measure your voltage at the output of 1st opamp. You will have excellent sensitivity.The best nulling i was able to achieve so far was around 50mv (on a scope).
Of course there may be exceptions,as the ones who want to make "universal coils"

Regards,
Fred.

[ivconic]

Ivica who is the voltage tension at Serbia (230V or 110v). I want to know what to do with chargers for (video camera and mobile phone).
Regards

230V of course!

[Darko]

One strage thing happend with my TGS before 308s go to the rest. I don’t know, maybe by mistake i shorted some connections, I don’t know, but after I put all IC’s (except LM308s) in sockets and turn TGS On ,audio tone become very loud wille detecting. I mean very loud! Loud like in batt test! And without changes in sensitivity! With good sensitivity even with nonchalant nulled coil. Also, like Max explain: "with 1M instead is a totally flat response, always loud... independently by target size or distance...“. But there on my PCB that 1M resistor was omited! After that 308s go bye, bye. I think. Now all is the same but sensitivity go down and audio become barely audible. So seems here I have some ghosts. Or just I have to learn much more about electronics.

Regards,
Darko

[detectoman]

question for anyone:

i purched one oscilloscope used this day, of name tektronics tipe 422 in 100 dollars
have anyone opinion on these?
is good?
or is discontinued?
what say me
thanks
apologies bad english
detectoman

[Darko]

Hi Max, Ivconic and others,

I think that Royal sabre is better than Golden sabre. Here is its shematic:

[ATTACH]3358[/ATTACH]

It has additional controls like pinpoint etc.

What do you think? Both are similar... so you can simply try Royal Sabre on your Golden sabre pcb.

Regards,
1843

Hi 1843!

Do you have some file or jpg of Royal Sabre PCB?

Regards,
Darko

[tiktak]

Hi,

Hi,
Max.
Can you give more details about this circuit.Because I have found that the problem is in the multimeter that I use for nulling coils!When conect like you say to try to null I have noticed that when I reach 0.00 mV the zero moment is now short,but wide!I can moove noticable distance RX over TX and multimeter reads 0.So I am pretty shore now that this is waht is messing me!
What multimeter did you use for sucsesfull nulling?
Thanks

[Fred]

Hello Tiktak,

I am sure any voltmeter will do the job, you just have to put it in AC at the output of lf353 (pin 7) and you will find that the best nulling is very dificult to find,no dead spot at all!
and you will never get 0v if everything is normal...
Good luck,
Fred

[Max]

One strage thing happend with my TGS before 308s go to the rest. I don’t know, maybe by mistake i shorted some connections, I don’t know, but after I put all IC’s (except LM308s) in sockets and turn TGS On ,audio tone become very loud wille detecting. I mean very loud! Loud like in batt test! And without changes in sensitivity! With good sensitivity even with nonchalant nulled coil. Also, like Max explain: "with 1M instead is a totally flat response, always loud... independently by target size or distance...“. But there on my PCB that 1M resistor was omited! After that 308s go bye, bye. I think. Now all is the same but sensitivity go down and audio become barely audible. So seems here I have some ghosts. Or just I have to learn much more about electronics.

Regards,
Darko

Hi,
if things change when e.g. you move from sockets ICs is probably something related to soldering of some pin at sockets... so I suggest you check that too. Your soldering work must shine, if not shine there is possibility of wrong solder joint.

If you use TL081 instead of 308s TGS will work too (but not as good... a bit less sensitive at least on mine)... then you can compare results.

Also, I've posted pictures of fake 308s sold me by a shop... they proved fake devices that gives lot of erratic noise and unpredictable results: sometimes they seem really good... but after a while , also some minutes only, they can generate enormous amount of noise. I suggest you test with various IC for teh reason that if you will see a stable operation with e.g. TL081 you can guess that your 308s are probably fake.

If you have burnt devices shorting some pads or tracks at the output stage could be things like you reported : stronger and easier saturations before device totally damaged , that's why buffer stage damage could follow a thermal runaway inside the case of IC... then you can check for that (before they rest forever) touching case of them... if warm thermal runaway happened due to initial "stress" at output.

This could be explaination: now try TL081 there or metallic 308s.

Kind regards,
Max

[Max]

question for anyone:

i purched one oscilloscope used this day, of name tektronics tipe 422 in 100 dollars
have anyone opinion on these?
is good?
or is discontinued?
what say me
thanks
apologies bad english
detectoman

Hi,
is discontinued dual channel BW 15MHz scope... (of great brand)...if in good conditions and working it's just right what you need here to see all stuff on the screen.

Don't know if 100usd is good price for it anyway... but if is in good shape think that could be fine.

Kind regards,
Max

[Max]

Hi,
Max.
Can you give more details about this circuit.Because I have found that the problem is in the multimeter that I use for nulling coils!When conect like you say to try to null I have noticed that when I reach 0.00 mV the zero moment is now short,but wide!I can moove noticable distance RX over TX and multimeter reads 0.So I am pretty shore now that this is waht is messing me!
What multimeter did you use for sucsesfull nulling?
Thanks

Hi,
I use scope ... but any good AC millivoltemeter will do the job. Also Fred is right... you can measure at pin7 of LF353 for minimum voltage saving you the work of making yourself amplifier/millivoltmeter circuit.

It's your choice.

Best regards,
Max

[1843]

Hi Darko,

Sorry, I have only the schematic.

Regards!

Hi 1843!

Do you have some file or jpg of Royal Sabre PCB?

Regards,
Darko

[Darko]

Hi,
if things change when e.g. you move from sockets ICs is probably something related to soldering of some pin at sockets... so I suggest you check that too. Your soldering work must shine, if not shine there is possibility of wrong solder joint.

If you use TL081 instead of 308s TGS will work too (but not as good... a bit less sensitive at least on mine)... then you can compare results.

Also, I've posted pictures of fake 308s sold me by a shop... they proved fake devices that gives lot of erratic noise and unpredictable results: sometimes they seem really good... but after a while , also some minutes only, they can generate enormous amount of noise. I suggest you test with various IC for teh reason that if you will see a stable operation with e.g. TL081 you can guess that your 308s are probably fake.

If you have burnt devices shorting some pads or tracks at the output stage could be things like you reported : stronger and easier saturations before device totally damaged , that's why buffer stage damage could follow a thermal runaway inside the case of IC... then you can check for that (before they rest forever) touching case of them... if warm thermal runaway happened due to initial "stress" at output.

This could be explaination: now try TL081 there or metallic 308s.

Kind regards,
Max

Hi Max,

things changed when I short accidently + and - voltage on the board. At that time the resistor 22R got burned. After replacing it, sensitivity come into being 15-20cm in air for 2cm coin and audio become barely audible. Before TGS burned, sensitivity was 32-35cms with normal audio. Then I decided to replace all of IC's and transistors. Heh, heh, easyest way for me to fix electonic stuff. At first I soldered IC sockets on board and then replace all of transistors with new ones, and put new IC's in sockets (except LM308s because I wasn't have new ones, neither TL's. Anyway I think LM308AN I have already on board are original) and change also speaker with new one. And voila! Loud and clear audio.Like in batt test.Very loud. More, strong then first time I tryed my TGS at Ivconic home with his exelent coil. Audio was loud but sensitivity remain 20 cm. Then I start search for errors on board. Clean flux, and resoldered some pins and... at the end audio deceased. Well, for such audio is better to die honorably than to live in shame. Now I'm waiting for a pair of metalic LM308H and couple of TL081. Just in case I'll first try with TL081. Will see tomorrow.

Best regards,
Darko