TESORO GOLDEN SABRE

[nelson]

TL082

Hi Max and Ivconic, and thanks both of you for replacement information.
Unfortunely can´t get that LM308 here. So i ll replace it with TL082 and see what´s going on.
Ivconic, th ehole pcb is build considering ICs base on it. I agree, that is a good way to test diferents alternatives on components.
Regards
Nelson

Hi guys,
unregistered and nelson...
well I think you could use TLC2262 if you can find ! I found them very good and stable, little noise, little consumption , very good dual op amps for metal detectors. They are in bandido circuit as you can see. Use them instead of lf353. You could use also:
ts272
ts27m2
ts27L2
tlc2252
tlv2262
If can't find one of the above use (but take care on consumption) :
ne5532 (good noise figure but 6ma consumption)
lm358 (but is noisy)


NELSON tl071 is a single op amp, you maybe mean tl072. Also tl082 could be
used but you could have trouble with a bit of noise there.

For LM308 I suggest (but hard to find):
NTE398

or easy to find the LF356/LF357 but consider that you don't need the capacitor at pin 8 anymore. You could leave them in ciurcuit cause LF356's pin 8 is not connected internally.

Best regards,
Max

[Max]

Hush, sorry i skipped your questions... Well, about nulling;
Best way is to use oscilloscope while nulling coils.
But not necessairly. As you said; good will and milivoltemer
would do the job just fine. Connect TX coil to oscillator.
Connect RX coil to m.v.metre...Try to achieve as less as possible
voltage at RX coil as you can get. Do not worry if you cant achieve
zero voltage. In most cases it will be impossible. It showed to me
that even up to 0.1 v coil can be useable,depends of device you are
using with it. Especially Tesoro G.Sabre is very tolerant. Very good
soluted at geb and disc stages, lets you to compensate eventual loses
from coil....Thats why i prefer G.Sabre, easy to make coil for it!
But most important thing comes after...to glue or whatever, coils in
housing, so good and stiff to eleminate any eventual movements later.
Also should stuff housing with some lightly mass....I do not want to
open this subject here, already all explained in Coils forums....
Nelson, best way to check is to use IC sockets anywhere you want to
experiment with different ic's. You are in good position to see
"in vivo" and experience "live" any differences among ic's.
Just pay attention on pin assignments...Yes, you may try LM1458 instead
LF353 for example....or TL082... buyt just for comparsions...
I am not satisfied with LM1458....but TL082 works almost good as LF353?
Now back to schematic; Yes! Again i made mistake! I omited those 2 resistors!
Damn! How it is possible? I guess it was in rush...not so good with software
for schematics...Thanks Porkluvr a lot again!
OK, now, for the last time, there is absolute correct and accurate schematic!
Yes, KT315, you are right. Adding parallel 1M resistor improved audio.
Now it is loud, and no decays while detected item estranged slowly from coil!
But i got another idea! I added switch, so we can have extra mode!
Without 1M resistor included in circuitry audio level is directly dependable
of signal strenght! There is very noticeable decay dependable of relative
movements of detected item. For example; as you removing slowly coin away
from coil surface, inch by inch, audio become more weak, decays respecting
reach/range. With 1m included, audio remains unchanged.
This can be very usefull on coinshooting! First we detect coin in Decay OFF
mode (loud and clear). Than switch Decay On and try to locate coin again.
Audio level can help us to distinguish about size and depth of detected item!
Very usefull...isnt it!
Regards!

Hi ivconic,
really nice work. I've tested mc1458 many times also on bandido I've made...with lot of troubles.
Now I've realized that these ICs are not so good for metal detectors like these from tesoro. I found that even lm358 is much better than 1458. I've much troubles with low voltage working of these devices: they suffer of erratic working at lower voltages.

Audio solution seems a really good idea! And also simple to be done.

I've found some good coins with bandido so far...but I'm considering building your GS mod.

Best regards,
Max

[Max]

I think that you will be ready before me!I haven't time lately!
For 308 I understend,but londering can I use TL071 insted of 353?
I have read that thy are equal and even cheeper replacement!
But not shore!
See you...
Have you made the board allready?

Hi guys,
unregistered and nelson...
well I think you could use TLC2262 if you can find ! I found them very good and stable, little noise, little consumption , very good dual op amps for metal detectors. They are in bandido circuit as you can see. Use them instead of lf353. You could use also:
ts272
ts27m2
ts27L2
tlc2252
tlv2262
If can't find one of the above use (but take care on consumption) :
ne5532 (good noise figure but 6ma consumption)
lm358 (but is noisy)


NELSON tl071 is a single op amp, you maybe mean tl072. Also tl082 could be
used but you could have trouble with a bit of noise there.

For LM308 I suggest (but hard to find):
NTE398

or easy to find the LF356/LF357 but consider that you don't need the capacitor at pin 8 anymore. You could leave them in ciurcuit cause LF356's pin 8 is not connected internally.

Best regards,
Max

[ivconic]

Finally FINAL !!!


Hush, sorry i skipped your questions... Well, about nulling;
Best way is to use oscilloscope while nulling coils.
But not necessairly. As you said; good will and milivoltemer
would do the job just fine. Connect TX coil to oscillator.
Connect RX coil to m.v.metre...Try to achieve as less as possible
voltage at RX coil as you can get. Do not worry if you cant achieve
zero voltage. In most cases it will be impossible. It showed to me
that even up to 0.1 v coil can be useable,depends of device you are
using with it. Especially Tesoro G.Sabre is very tolerant. Very good
soluted at geb and disc stages, lets you to compensate eventual loses
from coil....Thats why i prefer G.Sabre, easy to make coil for it!
But most important thing comes after...to glue or whatever, coils in
housing, so good and stiff to eleminate any eventual movements later.
Also should stuff housing with some lightly mass....I do not want to
open this subject here, already all explained in Coils forums....
Nelson, best way to check is to use IC sockets anywhere you want to
experiment with different ic's. You are in good position to see
"in vivo" and experience "live" any differences among ic's.
Just pay attention on pin assignments...Yes, you may try LM1458 instead
LF353 for example....or TL082... buyt just for comparsions...
I am not satisfied with LM1458....but TL082 works almost good as LF353?
Now back to schematic; Yes! Again i made mistake! I omited those 2 resistors!
Damn! How it is possible? I guess it was in rush...not so good with software
for schematics...Thanks Porkluvr a lot again!
OK, now, for the last time, there is absolute correct and accurate schematic!
Yes, KT315, you are right. Adding parallel 1M resistor improved audio.
Now it is loud, and no decays while detected item estranged slowly from coil!
But i got another idea! I added switch, so we can have extra mode!
Without 1M resistor included in circuitry audio level is directly dependable
of signal strenght! There is very noticeable decay dependable of relative
movements of detected item. For example; as you removing slowly coin away
from coil surface, inch by inch, audio become more weak, decays respecting
reach/range. With 1m included, audio remains unchanged.
This can be very usefull on coinshooting! First we detect coin in Decay OFF
mode (loud and clear). Than switch Decay On and try to locate coin again.
Audio level can help us to distinguish about size and depth of detected item!
Very usefull...isnt it!
Regards!

[nelson]

PCB

Hi, yes i already have the pcb and some components mounted (resistors, caps and some IC bases)
Don´t know how performance will be afected when i replace some ICs. So this will be confirmed when the project get finish.
Regards
Nelson

I think that you will be ready before me!I haven't time lately!
For 308 I understend,but londering can I use TL071 insted of 353?
I have read that thy are equal and even cheeper replacement!
But not shore!
See you...
Have you made the board allready?

[porkluvr]

4k7 resistors Disc and GEBl

Whoops, I'm sorry I meant the 4k7, (not 5k1) resistors (2x) in the signal channels.
This ommission will reduce signal gain by about one hundred (depending of frequency of interest). Those two resistors are easy to miss because the original diagram is kind of "busy".

I forgot about the other LM358. I wouldn't bother you about battery test!

Wait a minute, didn't you get some sleep last week?

[ivconic]

"...12v/1.3Ah...enough supply to let detector stay switched off for ..."

STAY SWITCHED ON...

Am i tired or what? Havent sleep for over than 50 hours....Good night!

[ivconic]

Porkluvr, i do not pay to much attention on batt. test....Whenever it is switched ON it makes a lot of "noise"...Some battery test!?
Maybe i made mistake there? Right now not able to check sch.
I am usin almost at all my detectors accu. 12v/1.3Ah...enough supply to let detector stay switched off for hours...days...
Do not need any batt.test at all. Also do not need noise in some situations.

Anyway, thats why i disconnected line for test and offered option to "PUSH" button if any test is needed....Also tied ordinary capacitor instead tantalum....same thing....

Unregistered i am sorry but i do not need to answer on qustions like that....You should have some data charts (free to download) - comparsions charts for op-amps.....No i do not think that you can substitute LF353 with TL071...not at all...
Yes, you should register.....

[porkluvr]

missing resistors?

Hello again -
***********
Oh hey, did you intentionally leave out the 5k1 resistors next to the bipolar caps on LM358 (-) inputs?
***********
Thank you for the scoop on coil construction and hook-up. I see what you mean about the OO coil being unwieldy. That would drive me nuts. Again.

To people wondering about replacing LF353 with TL072: They are almost exactly identical and work the same.
TL081 may work, and may be cheaper than LM308, but it consumes about 3X times more power - and it won't work any better. Pay now, or pay later.

Ivconic, you're right about the LM308 being hard to replace. I'll venture that LM308 pioneered and still sports an -almost- unique combination of features. (PMI) Analog Devices copied it with their *obsolete* OP08. Linear Technology now makes the LT1008. Whuuut else is there?

I have several of (dual) AD706 in SO08 package that -should- work like two LM308 with "custom compensation" built-in. I'll have to wait and see. I've never used a Golden Sabre, and so I won't know the difference anyway. It should be OK.

[kt315]

OK KT315, I'll try that way. Later repost results...Thanks!

Unregistered.....Just read whole thread...no need for "rain of questions"....
You have already explained everything here....read from 1st page...
Regards!
BTW...wish u luck!

pls, change U101a on NE5534 or another one opamp-in-dip. not use two opamp-in-dip for preliminary RX amplifier . or then second opamp do unused.

[Qiaozhi]

Hi,
IVCONIC:
Can you just tell me can I use TL071 insted of 353?
Will this change be equal?
Can you also PLEASE explain how to conect the switces?
Thanks

p.s.I have read all more than 20 times
Just beginer

Why don't you register?
It's very simple, and you no longer have to type in the special code in order to post anything.

HEllo!!

Hi,
IVCONIC:
Can you just tell me can I use TL071 insted of 353?
Will this change be equal?
Can you also PLEASE explain how to conect the switces?
Thanks

p.s.I have read all more than 20 times
Just beginer

[ivconic]

OK KT315, I'll try that way. Later repost results...Thanks!

Unregistered.....Just read whole thread...no need for "rain of questions"....
You have already explained everything here....read from 1st page...
Regards!
BTW...wish u luck!

NELSON

I think that you will be ready before me!I haven't time lately!
For 308 I understend,but londering can I use TL071 insted of 353?
I have read that thy are equal and even cheeper replacement!
But not shore!
See you...
Have you made the board allready?

????PLEASE HELP???????

Hi,
Can I replace LF353 whit TL072?Will this afect the preformance?
Thanks