TESORO GOLDEN SABRE

[Max]

the big problem with obsolete parts...

Are you certain that the comparators are not going into oscillation? This would cause the exact symptoms you are experiencing.

Hi,
yes of course... output comparators are always on the point of saturate when bad things are in the circuit (like the TL062 of notch... very bad idea having one there).

But that could not be the problem.

I noticed that 2 spare LM308N I bought last week have strange markings... so seem fake-op-amps.

They have a N like the National logo ...but different from it...on the left but I start thinking they are fake devices from asia... probably some LM741 with erased markings and then relabeled as LM308N!

I say that cause I had the metal-can ones and other parts and all seems ok with them but when I put those suspicious parts I get the device singing the macarena.

I have to post pictures of them... but can't take at the moment.

I trust people at shop who sold me that stuff and so think that the distributor they buy from was fraud by some singapore or something "dealer".

I was lucky cause bought just two... and don't need to complain with shop... for 1.80 eur expense... nevermind.

I've just signaled to the guys there and they are surprised of that. They bought something 40 of them cause there is request for DIY audio and RATs etc but now... with my little help... and few words of advertising I think they would throw all the stuff in the WC... and complain with distributor!

The story seems too strange ? Uhm... look at those pictures here:

http://sound.westhost.com/fake/counterfeit-p2.htm

So guys keep the eyes well open before buy many of these LM308N pearls.

Kind regards,
Max

[erolunall]

free Oscilloscope pc software

Hello All
http://xoomer.alice.it/sillanumsoft/index.htm
I find this link for PC . can we use for PC lap top Tesero deep model?
or Delta pulse PC model , İvconic, Max and other friends

Best Wishes
Erol

[erolunall]

free Oscilloscope pc software

Hello All

http://xoomer.alice.it/sillanumsoft/index.htm

Pc software for Osciloscope

İvconic I thing You can design İvconic deep scan heavy

how can use with PC for detection?

Regards
Erol Ünal

[Max]

Hello All

http://xoomer.alice.it/sillanumsoft/index.htm

Pc software for Osciloscope

İvconic I thing You can design İvconic deep scan heavy

how can use with PC for detection?

Regards
Erol Ünal

Hi Erol,
using a PC e.g. laptop for MD is possible but often not good in results as one can think. You can use e.g. an Sample-and-hold ic and AD converter (or just AD with integrated S/H) to convert an analog value and read it by a PC port then elaborate by some program etc
Robert Hoolko's project was similar to that... using an MCU to do calculations and having a PC interface for a VLF digital machine.
Much more easy is do same thing for the Pulse Induction type of detectors.
In both cases you need a very fast hardware for ADC and for calculations between sampling.
At the end the process is good and you can avoid almost all op. amps needed in conventional analog designs... and gain same performance of top of the range analog detectors but you'll not gain more depth that way cause you cannot increase SNR that way over and better than analog designs in practice... at least I saw that till now. Much is related to preamp. cabability and coils to give you readings in reliable way (ultra low noise) and for very small signals (under 1uV range).

Best regards,
Max

[Max]

suspicious fake LM308s

Hi all,
here are some pictures of them:

1 is upside of one of them look at the "N" (National)

2 is downside of it look at the number or "g"

3 is downside of both... then first difference the second have no number/g but seems have an epoxy melt in bad way ... but on the top they are labeled the same... even the timemark/fab is the same : it's M12AH and maybe mean they are from 1912 !

4 is original national lm308 look again at the National symbol (this time original) and compare with first picture: they are different.

5 is original one meta-can type

What do you think now ?

For me are fake LM308... also materials are bad quality... you can break leads just with a little pressure... but in original ones you can move pins without damaging at all.

Epoxy melt is not in standard of quality for National devices... I have many and not a single one is in these conditions.

Better to keep eyes well open before buy... these are S..T devices... maybe some LM748 relabeled.

Best regards,
Max

[Darko]

>>>>>>If notch section is present other bleeping is related to the bad choice of TL062 that's a very old and noisy IC: I have changed with TLC2262 from TI... and fixed that.


Hi Max!
What's about LF442N instead of TL062?

Regards
Darko

[Max]

>>>>>>If notch section is present other bleeping is related to the bad choice of TL062 that's a very old and noisy IC: I have changed with TLC2262 from TI... and fixed that.


Hi Max!
What's about LF442N instead of TL062?

Regards
Darko

Hi,
yes it's in the original schematic. I've not tested it ... but for sure is better than TL062 there.

Best regards,
Max

[Max]

noise considerations from notch section ic

Hi,
these are the numbers for input noise (@1KHz):

TL062 ----> 42nV/sqrt(Hz)
LF442 ----> 35nV/sqrt(Hz)
TLC2262 -> 12nV/sqrt(Hz)

So LF442 is better than tl062 but can't beat TLC2262 on that... I suggest you use tlc2262 if you find it... not so easy sometimes... somewhere... or a better dual op. amp.

Kind regards,
Max

[Max]

damn slow epoxy

my new epoxy seems a bit slow... it takes 2 days to harden well... and maybe 6-7 to get reactions end !

I've found a dealer that sell 1Kg at 9eur of that thing... it's clear and transparent ...used for making snow and surfboards and things like that... but man... it's slow slow slow !

Price is ok... but have to wait and it's boring...

I'm start feeling like Bear in the Big Wednesday !

What's your epoxy choice or preferences ???

Do you use different stuff... !?

Please expose here your epoxy/fixing stuff!

Kind regards,
Max

[Fred]

Thanks Qiaozhi!

[ivconic]

ADSL!!!

Guess what!? From now on i am using ADSL connection. Finally! Now i will be more often here and can spend more time...Just wait few more days me to setup everything right....

About TGSL;

Quiaozhi, yes you are right but i dont have original coil,

I performed few wild tests last few days trying to locate problem.

Problem is not in coil! I am sure. Problem is at first kop's at disc and gnd stage....But what? Oscilations....most probably!
I'll take a day or two to experiment and than post my notes...


Hysterezis! Yes, but i tried few mods without success..

Keep on trying!
Regards!

[Max]

Guess what!? From now on i am using ADSL connection. Finally! Now i will be more often here and can spend more time...Just wait few more days me to setup everything right....

About TGSL;

Quiaozhi, yes you are right but i dont have original coil,

I performed few wild tests last few days trying to locate problem.

Problem is not in coil! I am sure. Problem is at first kop's at disc and gnd stage....But what? Oscilations....most probably!
I'll take a day or two to experiment and than post my notes...


Hysterezis! Yes, but i tried few mods without success..

Keep on trying!
Regards!

Hi Ivconic,
about bleeping again... are your LM308 original parts ??? look at them very well, I showed here why... there are a lot of fake devices from Asia that are sold by e.g. shops cause also european dealerd sometimes are victims of frauds from that not serious asian dealers.

If they are original national or motorola etc parts ok fine... they will be good and produce less bleeping.

I think problem is related more to op. amps noise than fets... in my TGS happens just sometimes at max sens with original LM308s in place.

Best regards,
Max

[ivconic]

Good question! But i think they are original.
Problem is at kop's...only not sure what should be the problem, yet..

[Max]

Good question! But i think they are original.
Problem is at kop's...only not sure what should be the problem, yet..

Hi,
this is a simple test.

Have you 2x TL071CN from STmicro from not more than 5years old production ?

If so you can use them in place of LM308s and ear for differences.

Do that if you can and you'll restrict the field focusing on 308s or comparators.

I've used for test also TL071CN of above from ST and got no bleeping at all, at max sens, with all the coils I have. Only drawback is that you need recent parts from ST (others seem not so good don't know why... maybe input noise optimization on that) and a reduction of about 5% depth.

I'm using at now 2 original LM308s from national but have sometimes bleeping at max sens... so I turn pot at say 95% max.

Performances are really good.

Best regards,
Max

[Qiaozhi]

Guess what!? From now on i am using ADSL connection. Finally! Now i will be more often here and can spend more time...Just wait few more days me to setup everything right....

About TGSL;

Quiaozhi, yes you are right but i dont have original coil,

I performed few wild tests last few days trying to locate problem.

Problem is not in coil! I am sure. Problem is at first kop's at disc and gnd stage....But what? Oscilations....most probably!
I'll take a day or two to experiment and than post my notes...


Hysterezis! Yes, but i tried few mods without success..

Keep on trying!
Regards!

I have 4 original Tesoro coils. If you send me one of your PCBs populated with components, I'll investigate the problem for you. As they say, two minds are better than one. I will even pay the postage both ways! How's that for an offer?