TESORO GOLDEN SABRE

[Geo]

Hi,

I think that a very good one new candidate would be AnkerSS60 (or some its brothers) but with a mod related to GEB... cause without GEB it will be totally unuseful on real soil.

Of course... we can also play with mods on osc of TGS more and more... putting out 30Vpp or more... and see what happens!

Maybe it will beat also SS60 that way in air !

What do you think ?

Best regards,
Max

Hi Max. Anker SS60 oscillator gives a signal of 140V p-p !!!!!
About GEB ........ it is about like TGS. It has a trimmer for GEB. But as on Tessoro when you willturn more the trimmer you maybe distroy the disc a little.
But the TGS if works ok (not to me until make a New coil) will be a very good detector. I have a xlt and a GTI2500. At disc mode on air are about the same with TGS. XLT gives 45cm for a coin 2Euro, the same the GTI with 12.5in coil. TGS with 12.5in coil will give 40cm for a coin 2 Euro, so in the ground will be the same.
Regards

[Max]

Hi Max. Anker SS60 oscillator gives a signal of 140V p-p !!!!!
About GEB ........ it is about like TGS. It has a trimmer for GEB. But as on Tessoro when you willturn more the trimmer you maybe distroy the disc a little.
But the TGS if works ok (not to me until make a New coil) will be a very good detector. I have a xlt and a GTI2500. At disc mode on air are about the same with TGS. XLT gives 45cm for a coin 2Euro, the same the GTI with 12.5in coil. TGS with 12.5in coil will give 40cm for a coin 2 Euro, so in the ground will be the same.
Regards

Hi Geo,
what's the story with Anker TX ? I mean I read an Anker's post that say

TX - 50-60 turns wire diameter 0,3мм

Then when I've simulated circuit I got that to have 140Vpp at out you need use at least a 18.5mH inductance coil at TX... otherwise you get less voltage cause of resonance.

What about frequency too ? I get 140Vpp at 3KHz not 6.2KHz for TX.

Am I wrong ?

Look diagrams:
first is with coil = 5mH
second is with 18.5mH

Best regards,
Max

[Geo]

Hi Max.
My coil was 5mH and the frequency 6..Khz (i don't remember exactly, but not 3Khz). Voltage was 140V p-p.

[ivconic]

"..Anker SS60 oscillator gives a signal of 140V p-p !!!!!"

Not only detector but weapon too! Burn grass easilly! Also kill any eventual snake in that grass! Heh,heh,heh...!

Best regards!

[Max]

"..Anker SS60 oscillator gives a signal of 140V p-p !!!!!"

Not only detector but weapon too! Burn grass easilly! Also kill any eventual snake in that grass! Heh,heh,heh...!

Best regards!

Hi,
yes... maybe! 140Vpp ...uhm... I think it will ring and someone could hear it during burning... but my thought is about if we can mount one of this weapons on TGS... to see what happens... if plastic melt or something... or just if it will detect (in air) coins at 70cm...

Who knows ?

Best regards,
Max

[Geo]

140Vp-p, Yes. So when you try to Null the coil if you will take 200mv on Rx coil then you are OK
Another story
Bye

[ivconic]

About TGS power...
I was thinking to mod oscillator and gain more power. No. Now i have another approach to this subject; to put square oscillator there and try to filter harmonics...It will be easy to filter RX with bandpass...but how to filter TX.??? Even when quartz oscillator used, during dividing, each of divider involve some own hum and proceed it further. At the end we have harmonics too. It is not easy to filter output at all!? Damn! Especially nearest upper and lower harmonics. If quartz is overtoned (usually they are) than is possible to have stronger harmonics than leading frequency. I saw that in practice many times.
Least quartz i have is one from the clock. 32kHz. Must be divided with 2.
I measured 6000 DI Pro oscilator with Spectra spectrum analyzer. The heck!
Sideward harmonics were 70% amplitude of main!!!
6000 DI/Pro is fine detector, but i noticed some drawbacks in real prospecting with it....and those are (i can swear) due unperfectness of TX-ed signal..
So now, these days, i am exploring this....

[ivconic]

Now....idea for thinking further;

Sidewards of 32kHz are 16kHz and 64kHz. Right? How about "tribander"?

*16kHz for prospecting, (actually this is to high for prospecting)
*32kHz for coin shooting,(not bad for coinshooting)
*64kHz for nuget hunting.(perfect for nuget hunting)

3 separate (exchangeable) coils...etc.

Ha? How about this? To use drawbacks and turn to benefits? Ha?

[ivconic]

In this case, actually, no need to choke harmonics...at least sidewards, which are stronger in spectrum...Some "soft" filter can be applied to choke only far harmonics....piece of cake!

[ivconic]

"Dead sea" here...?
I think, I'll better dance now!
Vaya con Dios!

[Geo]

Hi Ivconic.
If you have audio generator connect it to the base of oscillator and play with the square signal (change frequency and duty cycle).
Try to modify the circuit so to put the coil in series with collector (resistance 2k2 don't need)
If you have not generator i can do it when i will finish the coil
Regards

[Max]

About TGS power...
I was thinking to mod oscillator and gain more power. No. Now i have another approach to this subject; to put square oscillator there and try to filter harmonics...It will be easy to filter RX with bandpass...but how to filter TX.??? Even when quartz oscillator used, during dividing, each of divider involve some own hum and proceed it further. At the end we have harmonics too. It is not easy to filter output at all!? Damn! Especially nearest upper and lower harmonics. If quartz is overtoned (usually they are) than is possible to have stronger harmonics than leading frequency. I saw that in practice many times.
Least quartz i have is one from the clock. 32kHz. Must be divided with 2.
I measured 6000 DI Pro oscilator with Spectra spectrum analyzer. The heck!
Sideward harmonics were 70% amplitude of main!!!
6000 DI/Pro is fine detector, but i noticed some drawbacks in real prospecting with it....and those are (i can swear) due unperfectness of TX-ed signal..
So now, these days, i am exploring this....

Hi,
of course there are harmonics using square wave... that's the multifrequency minelab say... you know. They use the peaks of harmonics to do further analysis on target composition apart just using fundamental freq. of oscillator... then you also know that some MDs like e.g. white's models use that in RX instead again of fundamental... that could improve SNR in some kind of circuits... but I'll be aware of them cause TGS is much easier machine and can't do any good with that other (and higher) frequencies.

The quartz approach is not any good... apart stability of frequency , but you gain more and more stability when you divide fundamental many times ... e.g. use a 1MHz fund. xtal to get 7812.5Hz square wave... that's cause xtal has about fixed ppm variations due to e.g. temperature (or vibrations etc) and if you divide many times you also divide error many times... and got really stable source: an example are 32.768KHz watch xtal that are used to get the 1Hz signal in quartz watches.

If you use just 1 division making e.g. 32768/2 = 16384Hz you get 16KHz but with an absolute error that is just 1/2 of error on fundamental (maybe 20-30Hz... so you get 10-15Hz error... good for VLFs but very bad for e.g. BFO or OFF-resonance).

Problem with square wave is related to discontinuity of signal: greater is discontinuity greater is amplitude of harmonics in real world.

So you'll do better with e.g. trapezoidal wave... having not too sharp rise of waveform. In triangle and trapezoidal wave the rms value of harmonics is inversely proportional to the square of harmonic number... that make power of them decrease faster than in pure square wave case.

Of course... all "real" square waves out there are trapezoidal ones... cause of real components employed you'll haven't any vertical rise from you circuits... but considering rise angle things could change a lot.

Also you have to consider that is not easy making a perfect square or trapezoid appears accross coil leads cause of L, R and other params that make your out circuit distort the output signal. This also will have effect on harmonics generated.

So I suggest you try to optimize power factor of TX using that advices of above... trying some trapezoidal approach instead of "pure" square one... it's not easy filtering harmonics on an existent design... better reducing them at TX directly.

Best regards,
Max

[ivconic]

Good points! Thanks. Huh, my problems remained; dont have good oscilloscope to be sure what i am doing. This one KEW (you saw it on photos) is very old, doesnt have synchronisation!! Very old. Audio generator is not a big deal. I already made simillar based on XR2206...pretty useable.
Yes Max, new idea opened new questions and new problems. Correct. If this turns as good idea, than i have to agree with you on this; TGS is not right platform to apply those. It must be considered to design quite new device, from front end to audio. Not piece of cake at all. I will go step by step and see what happens?
Regards!

[Max]

Good points! Thanks. Huh, my problems remained; dont have good oscilloscope to be sure what i am doing. This one KEW (you saw it on photos) is very old, doesnt have synchronisation!! Very old. Audio generator is not a big deal. I already made simillar based on XR2206...pretty useable.
Yes Max, new idea opened new questions and new problems. Correct. If this turns as good idea, than i have to agree with you on this; TGS is not right platform to apply those. It must be considered to design quite new device, from front end to audio. Not piece of cake at all. I will go step by step and see what happens?
Regards!

Hi Ivconic,
I agree with you. If the target is optimizing more TGS... just few mods on osc are needed I think... without touching all the rest of RX, disc etc parts of circuit... then we can add a new kind of audio generator for it cause of bad sound response of the simple transistors approach by original schematic.

If the target is experimenting with multifrequency or with near to square TX wave it's better the option of design a new detector with e.g. active filters and all needed to perform well ignoring unwanted harmonics.

In the second case I think you'll need to pay attention and care on the RX front-end and filters then you could analize the received signal the usual way. I think that the increased power due to square signal at coil have some drawbacks on existent design approach... cause it will fit better with traditional sinusoidal TX approach... but if design will keep out worse effects due to harmonics maybe will result in a really powerful MD.

Of course, you need some new scope for testing... can't you find one there e.g. some russian made product ? I saw some of them some years ago... (in the first 90's) there were not bad above 15-20MHz, 2 channels and internal trigger like western made stuff of 70's.

A guy offered me to buy one for the equivalent of 60$ at that time... in a kind of electronic flea market of surplus stuff (radio and the like) but then I refused cause I had already much more powerful stuff... made in Japan.

Best regards,
Max

[tiktak]

Hi,

Hi Max,
I noticed that you make 255X137 coil and I were using 255X137 for former size!
Which is corect because I think I saw in some post that former should be!?!?!?
Did you wind the TX and RX in same direction?
Thanks