TESORO GOLDEN SABRE

[Hush]

Hi Geo! Nice to see you again. It is new multimeter.Check it, how?

[Geo]

Check your multimeter ......

[Hush]

What the hell...

Ohhh..
I am in big trouble!
I spend all bloody day to wind coil, wind by wind, without any crossing of wires.I've used Chemelec inductance calculator and got results:
For 10 inch inside diameter coil (256mm) - O concetric coil
coil lenght: 0.2 inch (5mm)
wire diameter: 30 AWG or 0.27 mm with varnish
turns:117
inductance:7.1mH
I think that calculator is very, very good .
Everything looks fantastic, but no, no my friends! My freaky multimetar "told"
me the coil inductance isn't 7.1 mH (that should be RX coil), but 9.8 mH!

Let's say y is specific resistance (I haven't that bloody letter).

R=y x l/S then l=R x S/y

y for copper is 0.0172 ohm x mm2/m
resistance of my coil is 33 ohm

S=r2 x 3.14 ( I haven't bloody pi too) S=0.125 2 x3.14=0.0491 mm2
l=33 x 0.0491/0.0172 l=94 m

So, wire lenght of my coil is 94 m.

let's calculate on other way:
O=2 x r x 3.14 O=0.256 x 3.14=0.8 m

0.8 x 117 turns= 94 m - the same results.
So what, you can say, but now I am sure the number of turns is correct-117
And what now? Should I trust to my multimetar , it looks good, think it isn't from China, but who knows? Or should trust Chelmec?
Immediatly need help... help... help...
Yours Hush

[Leto]

VCO

Originally Posted by Max
About tones... I think the way one could wire such a mod. is related to the 2 channel informations:
watching at voltages of the 2 lm308 outputs is the key to get multiple tones.
One could also use outputs of comparators near the sens pot.

When iron is present channel output voltages are in oppositions, thus giving zero effect on output. When coloured metal is present, instead, channels have similar behaviour.
That way is possible making a multitone information.

Problem is that if you vary disc pot setting you'll vary also audio response, and that's no good, confusing the user. So a real mod. must be place disc pot as trimpot with minimum setting, then leave the user just ear the sound difference to disc stuff, not moving the pot (as in original GSabre design).

Max very good idea to take audio input at 308 outputs. To avoid disc. pot problem it could be possible to add one channel only for multitone sound or use simply notch channell.

For further buffer I found following shematic interesting (posted by rumenisat on md4u.ru-forum) It's purpose is: colour metal identification with RGB LED - kind of a VDI. It could be used also for trigger of two audio oscillators with mixer to produce audio multitone ID.

[Leto]

amplifiers..

Hello Max and others..

do not know about TBA820's but I'm very much satisfied with old lm388 - it works perfect. I connected it after C517 with 2k resistor it does just what's wanted: amplifies for 8ohm impendance speakers. Input resistor is really needed (or the amp. input is overloaded) maybe also lower gain transistor in place of C517 would be OK.
Higher consumption could be a problem for someone (10-15ma) but personally I do not use 9v batteries for long time now.

[Max]

Hi,
Max.
Ok,ok!
Just wanned to know for shore!You say that 38 cm for a dime is not posible.
But 1 cm is dime size.

Nice simple mode I will try this 1n !
Just to tell that now I have found LF353P!!!!At last.
Now my components are 100% same as original.
And the last thing to do is good coil!
And NE566N what do you think is this make differance in audio.Ivconic tell that he search for another solution!This mean that its not so good modification.

Hi,
I never said that e.g. detection of 1cm diameter coin is impossible at 38cm.
I just said that you need a larger diameter coil (e.g. 28cm or more) and a very well done tuning... but as Ivconic right stated you'll have a difficault pinpointing respect to e.g. 22cm diameter and also much more geb problems.

For sure is impossible with a DD22 coil, at least with a small power VLF like GSabre is... no dubt about that.

I think that 566 is good for vco, but problem is that if you have no more informations of e.g. metal type by audio is almost unuseful having the vco, if not for e.g. evaluating the strenght of signal, thing that you already have in original GSabre.

VCO option could be very interesting if the disc informations could determine different frequencies for different metals (multi-tone id).

Kind regards,
Max

[tiktak]

Hi,

Hi,
Max.
Ok,ok!
Just wanned to know for shore!You say that 38 cm for a dime is not posible.
But 1 cm is dime size.

Nice simple mode I will try this 1n !
Just to tell that now I have found LF353P!!!!At last.
Now my components are 100% same as original.
And the last thing to do is good coil!
And NE566N what do you think is this make differance in audio.Ivconic tell that he search for another solution!This mean that its not so good modification.

[erolunall]

detection range TGS

Hello all

I wonder TGS detection range for big metal object for example car or 1 m iron object and I want to ask to ivconic secret of his succes on TGS)
thanks
Erol Ünal

[Max]

Hi,

FOR Tiktak:

Have we to split hairs here ?
If he said that's 1cm diameter that's so. Maybe is an older coin.


For Ivconic:

got an idea... to get a better sound:

- do you see the 22nF cap that is on pin5 of last LM358, just after the 1n4148 diode ?
my thought was that if I'll change its value to e.g. 1nF I'll get a better audio response and faster response of detector.
I've made and seems it works: got a better audio detection at maximum depth (about 27cm for 1eur coin); some instability only in all-metal mode.

It's not a big mod but I'm satisfied of sound response at maximum depth now, seems more consistent sound.
I think that with headphones I don't miss deeper targets this way.

If you have time try the little mod.

Best regards,
Max

[tiktak]

Hi

Ehm, it's ONE SERBIAN DINAR , approx.1cm diammeter nickel coin.

Ivconic what is this coin 1cm?The smalest I think is 1,5cm D!
please check again!If this is true than I am not even close to the results that I have to achive!!!!
Can you preforme air test with 1 euro coin and post results please~!

[Max]

Max,
Are you using metalbox for device and ground all to box?

Hi tiktak,
at now ?
No no, have just the PCB, wires, etc on table, no case for now. Have no time for that... just some rough testing.

On bandidoII I had to make gnd planes, then find a suitable metal box... but with GSabre PCB no need of anything. You can test as you want, it's really stable.

No problems.

Kind regards,
Max

[tiktak]

Hi

Max,
Are you using metalbox for device and ground all to box?

[tiktak]

Hi

Ivconic what do you think can I use CD3240 insted of LF353?
Will this afect performance?

[Max]

"..Ivconic can you tell us is the depth 38 cm in air with 28DD coil for dime?/what
you understand buy 1cm coin?/!"
Ehm, it's ONE SERBIAN DINAR , approx.1cm diammeter nickel coin. Since i already
used it so many times to check depth on almost all detectors,i ever saw in my life,
i just "established" it as standard coin with standard size, also standard alloy.
Why standard? I just had to have some reference according to which i can easilly
compare detectors. I could use any other coin,size,alloy...couldnt i? It is not
important at all. It is just my internal reference according to which i do a lot of
tests and checks, according to which i made several comparsions, which, on the other
hand, helps me a lot when dealing with some new,unknown design,project or original
detector...call it anyway you want. These comparsions gives me full right and
support to come here and freely claim some claims,like;
-TGS goes much deeper than Fisher 1266,
-TGS is superior over White's CL3,
-TGS goes deeper than Musketeer,
etc.etc.etc.
You can not judge about one detector,if you havent seen and tested other! Can you?
More detectors you tested,more experiences you have.More experiences you have -
easier for you to know what is good and what is not.
If photo of detectors collection Carl posted here is his own collection,than he must
be very happy and experienced man on this subject!?
Of course, meaning that he previously tested all of those and made comparsions charts?
Back to coin; why coin? Simply, one standard coin is the very best reference we can
use here. By the same coin i can test my detector here in Serbia, same as you can in
Guatemalla or New Zeland...
Other test reports doesnt mean rule. For example if i say here:
" I detected 20 roman coins at 20cm depth on old roman location..."
This should mean nothing to you! What coins? What size? Alloy? What soil?Compounds?
Mineralization? Day,night? Moisture? Propagations?
Too many decisive factors can
cause HUGE DEPTH DIFFERENCES between my handmade detector here, and your very same
handmade detector, there in Guatemalla!!!
Further,those differences can confuse you even more! You can suddenly start thinking;
"..either ivconic lie here...either something i did wrong while making my handmade..???"
How can i gain ivconics results??? What is secret? Is he liar?
Or in case my results are worse than yours;
"..is ivconic ignorant,cant achieve results i gained...???"
So to make things much simplified, we should accept as common, only reports and results
made using same method of testing. It is not possible to simulate same ground conditions
(not to mention other factors), so, although rough and unperfect, we can only relly on
detecting one single coin in the air. Same size and alloy. I was thinking; nickel coins
are so usuall....1cm size also. It is not big deal for all of us to easilly find one
nickel with 1cm diamm. and use it for comparing.
Nickel alloys are also very interesting to testing discrimination circuitry.

"Flux chaining is "proportional" to coil diameter, if you use e.g. 28cm diameter you get
some more depth."
This is very important to understand! Benefit is more depth - drawback is loss of p.pointing
and eventual instabillity (more sensitive to ground conditions).
***********************************************
I put TL071 instead LM308...same! Very stabile and good depth. TL082 instead LF353, also
very good, but lost 2-3cm...
I also put 741 instead LM308!!?? When Sensitivity is max, lot of false signals, but
when lower to 1/3 very good behavior and descent depth!
LF353 should stay unreplaced. LM308 can be replaced with TL071,TL081 or some other.
*************************************************

About audio mods:
"I am not sure it will work? Audio buffer at TGS - LM358 across that 27K is "pulling"
some voltage in range -4.xx to +3.xx volts..if i measured correctly?
On my previous mod with LM566 i had to put extra fet J107 to trigg it to -12v...it
showed as only way to make LM566 stage to work good. Direct connection gave a lot of
saturation and various "squeeking" with noise...
Either some level converter should be applied before ordinary audio amp...?
I have rough idea on my mind,only dont have it as schematic yet. It seems it only few
fets more can solve the problem. I am thinking to experiment with small capacitances
arround gate and source to make some "delay".....we will see..
CZ5...? Ehm,at the time i was very impressed with it...Now my TGS runs deeper...Yet, i
idore CZ sound!"
Actually, here at TGS, MPSA13 is working partially as "chopper" - not just as
simple amplifier. It is not so easy to apply any audio on it.
This we should reconsider more detailed.
I do not have scope here at my workshop yet, so it is so hard for me to follow signal
level and distinguish the voltage range in which MPSA stay "closed", and at what point
it is "open". Real succes would be if we make a sort of "limiter", to limit lower
point for opening MPSA13. Why? Simply, than we could adjust it better to avoid eventual
and in some cases ocassional chaters and false signals. Or apply versatile front panel
preset and adjust it from case to case...Other words, small,mum,suspectable signals we
could "reject" from audio, and allow only good,strong and clear sinals to be amplified
by MPSA13.....
That's why i started thinking other way; simply to turn to fets..only dont have clear
idea yet...
Come to think; have you ever saw Bounty Hunter Tracker 505..xx something. Cheap one..
I had chance to work with. Low depth, not serious...toy. But! Disc. was great!
In disc mode there is great audio separation. If detected item is iron - audio freq. is
noticeable lower and polyharmonic, other hand; if item is "coloured" audio freq. is
noticeable higher and sound is clear - no harmonics!?
It is also motion detector, also no pinpoint mode...
I dont have its schematics to trace and copy those disc and audio stages....
It would be very interesting to see it and try to use it to mod TGS audio...?!
Anybody have schematic? Esteban posted something about it once......
***********************************************
TikTak try this;
Connect TX coil to TGS, do not connect RX coil at all. Connect RX coil leads to
ordinary multimeter and pick 2v range AC to measure;
Turn ON TGS. Look on multimeter. You will see AC current induced in RX coil...
If hardly unbalanced, AC voltage can be higher than 4-5 volts...
Now, start balancing coils. Try to gain least voltage possible. Do that very slow!
At my 28cm coil i gained 0.015 V.... But it took me 20 minutes to adjust coils.
"Nanometer per nanometer"....Next is to use "Super Glue" and glue both coils
togather, fast and carefully not to spoil gained balance. Why super glue?
It is drying very fast.It has no relative movements while drying! Later when dry,
you can use some extra mass or glue to apply over.
And that is all! You have good nulled coil!
BTW, it is not so hard to achieve absolute 'Null'. To balance coils so good to
read 0.000 volts. There is one "region" on overlaping part where no induction
occurs at all. But i would not suggest you to finish nulling like that!
I noticed many times, on many coils, very noticeable LESS SENSITIVITY if coils
are balanced that "good".
Best sensitivity is when coils have "critical" balance...but hey! Not to much
"critical".....we dont want BFO syndrome here!
Further, my best coils so far, are balanced in manner to produce inductions
between 0.08 - 0.015 volts. Already proven on real fields under real ground
conditions...Those coils are real "coin killers" at high deths..
************************************************** *************

Hi Ivconic,
I agree that direct connection for TBA820M's input was a bad idea... have connected then after C517 and audio was loud etc but I was not satisfied.
About "delay" you mean a monostable ? I was thinking too same thing... cause the weak audio response is due, at higher depth, to fast commutation of op. amps... (too fast) to get a good sound.
I think that e.g. a 300mS monostable could be fine there... adding some inertia when saturation occours.
Of course, pinpoint would be damaged by greater inertia.

About tones... I think the way one could wire such a mod. is related to the 2 channel informations:
watching at voltages of the 2 lm308 outputs is the key to get multiple tones.
One could also use outputs of comparators near the sens pot.

When iron is present channel output voltages are in oppositions, thus giving zero effect on output. When coloured metal is present, instead, channels have similar behaviour.
That way is possible making a multitone information.

Problem is that if you vary disc pot setting you'll vary also audio response, and that's no good, confusing the user. So a real mod. must be place disc pot as trimpot with minimum setting, then leave the user just ear the sound difference to disc stuff, not moving the pot (as in original GSabre design).

Do you think is possible that way ?

Kind regards,
Max

[tiktak]

Hi,

Thanks
Ivconic for the INFO
Will try make another coil soon.
Like yours.