TESORO GOLDEN SABRE

[Max]

other pics...

[Max]

other pics....

[Max]

For Ivica and Max.
Do you tried to connect the Rx capacitor (15nf) at the wind of coil before the cable (from coil to detector)
Regards

Hi,
not on TGS, I've made on bandidoII... well works... but I respected original Tesoro's design and haven't put cap inside coils... so now I can use bandidoII coils on TGS too.

It's your choice... I cannot see any real advantage on these designs doing so.

Best regards,
Max

[Max]

Hi Max. I have not a 1Euro-cent to try, so i found at my Lab a old bronze coin (unknown) 7mm diameter (yes it is very small). I detect it at 20...22cm. I don't say you for sure 22 or 20 cm because at full sens as i wrote before i have some parasitic signals.
Regards

Hi,
yes I detect at some more cms but maybe cause coil is 10'' so field density is different.

I think that's ok for a DD32cm diameter round getting very little stuff at a bit less depth.

Best regards,
Max

[Max]

Hello Ivica.

Made a testboard, giving me also some problems. If I pas my hand over the print it wil give an echo..... can be becorse of the long connections.?!
Can also be a problem in the desing from the print.......?!
If I pul out the zener 4v3 I got the same signal at 353-1 that you have, look at the screenshot.The transmitsignal has so also some effect.

The first board is working fine, it is the test board that gives problems, wel wil check and test tings, if answers are there I let you know.

Ap

Hi,
my signal at pin1 is exactly the same as this your last one.

I don't understand exactly why... but I think it depends on LF353 type.

Did you use the same part for the previous test (perfect sinus) or is a different LF353 there ? What's brand of first part you tested and what's second if different ?

Also Geo has a perfect signal on pin1 and that's again strange having such different behaviour from one board to another... using always LF353 there !

My guess is that there is some difference from some lf353 to others that make damped osc appears...

BTW I've a National LF353N on circuit... and it give me damped oscillations like I see in your last post...

Kind regards,
Max

[Geo]

Hi Max. Great work.
I will check the photos with mine and i will write the results.
For start.........
The out of LF353 is 800mv p-p. The 353 has a gain of 220/5.5=43.1 , so the input voltage or the coil out is 800/43.1=18.5mV. This is the out voltage of your coil after null. At my detector the voltage is 150mv p-p (maybe better null).
When i play with disc pot i have a phase change of about 80degrees, but you have about 40 degrees. Why???????
Ok you will tell me that your detector works ok and mine don't discriminate good, but this is an other story. I connect the channel1 at the Tx coil so maybe to be this the reason. I will try it later with same connection with you.
But you have a problem near the LF353. Ivconic said that it is exactly the same if you put TL082. So if you have one check it.
Regards

[Max]

Hi Ap and Geo,
from what I know there are only 5 manifacturers of LF353:

- National
- Motorola
- STM
- Fairchild (but really obsolete now... and almost impossible to find)
- Texas Instruments

I've National's ...what's yours ?

Kind regards,
Max

[Geo]

Hi,
not on TGS, I've made on bandidoII... well works... but I respected original Tesoro's design and haven't put cap inside coils... so now I can use bandidoII coils on TGS too.

It's your choice... I cannot see any real advantage on these designs doing so.

Best regards,
Max

Hi
Generally is better the transfer cable to be connected to a tuned circuit than to tune after the cable. Always theoretically

[Max]

Hi Max. Great work.
I will check the photos with mine and i will write the results.
For start.........
The out of LF353 is 800mv p-p. The 353 has a gain of 220/5.5=43.1 , so the input voltage or the coil out is 800/43.1=18.5mV. This is the out voltage of your coil after null. At my detector the voltage is 150mv p-p (maybe better null).
When i play with disc pot i have a phase change of about 80degrees, but you have about 40 degrees. Why???????
Ok you will tell me that your detector works ok and mine don't discriminate good, but this is an other story. I connect the channel1 at the Tx coil so maybe to be this the reason. I will try it later with same connection with you.
But you have a problem near the LF353. Ivconic said that it is exactly the same if you put TL082. So if you have one check it.
Regards

Hi Geo,
you are about right on coil, I've used one DD nulled at 15mVpp on scope to make test cause I cannot dismantle the DD255/137 I actually use from pole at now.

It's glued down on a piece of wood.
Actually there isn't any great attenuation of sens... but I use better nulled coil on real soil due to GEB.

With TL072/TL082 instead of LF353 the things are all the same same ringing at pin 1... all the same.

Kind regards,
Max

PS: coil use Ivconic's specs

[Geo]

Hi Ap and Geo,
from what I know there are only 5 manifacturers of LF353:

- National
- Motorola
- STM
- Fairchild (but really obsolete now... and almost impossible to find)
- Texas Instruments

I've National's ...what's yours ?

Kind regards,
Max

I will tell you later when i will go to the Lab (in the underground )

[ApBerg]

LF353-1

Hello Frends.

Thanks for all the work you al have done ! Great is Internet !
I agrey with Ivica, the goldy light (golden sabre) with the right coil is a very good detector, it is working as top line detector !

But there are some strange things the signal at 353-1: I have LM393N and a LF353P think the N version is better.
The 'wrong' signal that Max has is the same as I had ,after reducing the TR signal !? (removed the stab.zener diode out the circuit)
So the TR signal, the C from 100pF and the Lf353 are parts in this together with Porklvrs 10K we have to find the answer. However with wrong signal it is also working !?

The problem Geo and I have:
Sometimes when i touch the pcb or the coil housing or any wire i have erratic signals (beep...beep...etc). Other times it works ok. I think that it must be shielding problem. If i will find it i"ll write you. I must go out to test it (when rain stops) because i am afraid that at my Lab there are a lot of parasitic signals.

The first board I made has no problems, the components are close on the board( no ic sockets) and connections are as short as possible, the second, testboard has lots off problems, I have long connections and use ic sockets !
I will tray to find out what is the main problem.

Best regards.

Ap

[Max]

Hello Frends.

Thanks for all the work you al have done ! Great is Internet !
I agrey with Ivica, the goldy light (golden sabre) with the right coil is a very good detector, it is working as top line detector !

But there are some strange things the signal at 353-1: I have LM393N and a LF353P think the N version is better.
The 'wrong' signal that Max has is the same as I had ,after reducing the TR signal !? (removed the stab.zener diode out the circuit)
So the TR signal, the C from 100pF and the Lf353 are parts in this together with Porklvrs 10K we have to find the answer. However with wrong signal it is also working !?

The problem Geo and I have:
Sometimes when i touch the pcb or the coil housing or any wire i have erratic signals (beep...beep...etc). Other times it works ok. I think that it must be shielding problem. If i will find it i"ll write you. I must go out to test it (when rain stops) because i am afraid that at my Lab there are a lot of parasitic signals.

The first board I made has no problems, the components are close on the board( no ic sockets) and connections are as short as possible, the second, testboard has lots off problems, I have long connections and use ic sockets !
I will tray to find out what is the main problem.

Best regards.

Ap

Hi Ap,
thanks for your reply... yes Internet make things really easy about echanging ideas... maybe also too much easy... anyway

I think that your thoughts about sockets and long wires are absolutely good... cause we always don't keep in mind there are side effects due to capacity involved using e.g. sockets and the like... BUT problem at LF353 pin1 is probably not caused by socket... I'm about sure of that cause I noticed that putting a TLC2262 there I get a totally different shape... and maybe that strange thing has much more to do with input bias current of op. amp. that's why I suppose the LTspice model of LF353 could be too good to be real.

But maybe I'm wrong ... who knows ?

What I know is that LF353 have 50pA bias and TLC2262 just 1pA... 50times less current! The TL082 has a typical value of 30pA bias at 25°C... but I suppose they are about the same thing compared to LF353 in same room temperature.

Maybe the simulator uses a different value ? I'm pretty sure that parameter is much involved in the ringing we see there...

The funny thing is that it works in any case

Best regards,
Max

[Geo]

For Max. My LF353N is from National. I traced again the signal but this time as you.. channel1 on out of LF353(Rx) and channel2 on the pin1 of LF353. The signal is very good
To Ap. I use sockets and pin connectors, so maybe one bad connection. I connected the Rx capacitor (15nf) on the coil and i think that i am very good. But i am not sure. Now i have problem with disc. When i change the disc pot i see a phase shift but i have not responce on the metalls. It beeps in any position. Ohh my god, all to me are happened,
So the solution ia one.
I go to drink 2...3 whisky and after all will be OK.
Bye

[Max]

For Max. My LF353N is from National. I traced again the signal but this time as you.. channel1 on out of LF353(Rx) and channel2 on the pin1 of LF353. The signal is very good
To Ap. I use sockets and pin connectors, so maybe one bad connection. I connected the Rx capacitor (15nf) on the coil and i think that i am very good. But i am not sure. Now i have problem with disc. When i change the disc pot i see a phase shift but i have not responce on the metalls. It beeps in any position. Ohh my god, all to me are happened,
So the solution ia one.
I go to drink 2...3 whisky and after all will be OK.
Bye

nice! we have same parts and read different things... now I need a whisky too

[Darko]

lele bre,bas bas.

No ivconic, tiktak is not my friend.Yet.I think.And he could not be me. I am sure of that.


Hah,hah,hah!!!
What kind of question is that? How i dug those coins..!?!?!? Simply, i detected those and dug them, one by one...Simply as that.
TikTak you are, almost always, asking me simillar questions..? Why?
Like you "investigating something in my posts"? Are you Serbian? Bet you are!
Are you, by some strange coincidence Darko? Bet you are! Or one of his friends!? If you want something to say here, dont hesitate...c'mon spell it!
But please do not ask me questions like that anymore....
"Half of rusty horse shoe..."!? Is it possible that there are some terrains without horse shoes "installed" in??
How i couldnt detect horse shoe? Simply, there wasnt anyone there, where i went to propsect... Even if were, my Dscrimination circuitry works very well, also my coils are nulled perfectly, so there is NOTICEABLE DIFFERENCE BETWEEN sound produced by horse shoe and coin!

Anyway, i am glad to see that you finally made coil with detection over 30cm...Bravo! Good job![/quote]