TESORO GOLDEN SABRE

[Max]

Ok,
So, I have to put -of multimeter and according ivconics schematic to check all elements starting from this 15n cap afther RX points on pcb?

I have just tryed with ac/dc adapter only louder sound!
So I will keep testing with two paralel 9V batteries for now.
Which element is the last in this testing?So I can imagine all!

Hi,
start at capacitor... and end at speaker!
No... just joke!

You need reach the last LM358... the one you removed. Between rx pads and it would be the mistake or mistakes. I think that could be a wrong component value or soldering.

If you can, test if voltage levels change at output of op. amps. when you near some metal to coil... just to know if they are blocked (saturated) or not.
A good test if you could see where thing starts becoming frozen...

Best regards,
Max

[Max]

Have you nulled the coil right ???

[tiktak]

Hi

How should I null the coil?I were thionking to use ivconics method.Conect to G Sabre and move untill get best point/deepest reading/!!
What will you advice me?
Thanks.
How to acive this?

test if voltage levels change at output of op. amps. when you near some
metal to coil?

And can the problem be in coil?
Only?

[Max]

How should I null the coil?I were thionking to use ivconics method.Conect to G Sabre and move untill get best point/deepest reading/!!
What will you advice me?
Thanks.
How to acive this?

test if voltage levels change at output of op. amps. when you near some
metal to coil?

And can the problem be in coil?
Only?

Hi,
oh man! Yes could be...
Ok. If your coil isn't nulled you get too much signal into first op. amp. and then it saturate easy.

So, first of all, you need to carefully null the coil. Look at previous posts:
you can do with multimeter too... be sure you get the minimum signal on rx coil at nulling. Then reconnect rx leads to PCB and go ahead with testing.

Ivconic uses that method cause he knows what he do... I mean he get the coil near to nulled and then adjust for maximum sens... he have experience with homemade coils...but if you try yourself... without making any preliminary adj on coils positions... with scope or multimeter... well you'll never get this stuff working!

So got the null first!

Best regards,
Max

[tiktak]

Thanks
Man I will try and then ask stupid and boring questions.
Just have made 3 projekts and cant get non working as I wish,so when first time saw thi GS project I have told myself this will work!!!!
Thanks

[Max]

Thanks
Man I will try and then ask stupid and boring questions.
Just have made 3 projekts and cant get non working as I wish,so when first time saw thi GS project I have told myself this will work!!!!
Thanks

I'm sure at end will work!

[tiktak]

In this case I should conect TX start point to pcb point V and TX end to U point.No shields/or with shields?/?And I will use 1k resistor,but which capacitator will be good?Electrolitic,ceramic?Whit what value?I have 4,7 mf electrolitic and 15n ceramic?I should put the multimeter in 1-10v range in AC
Thanks

[tiktak]

Max,
When I try to null with multimeter and conect only TX without shields THIS NASTY SOUND IS STILL THERE!!!
Its look like I reach right value!
Can I try now just to conect two RX windings start and end point to RX place on PCB just to test?
Or this is not good idea?
Thanks

[nelson]

Max, have you tried any GS coils? HOw where your experiencies?
Can you post your coils details to compare my expirencies with you.
Now i m working on the TX coils, same has Ivconic, but i ll have to take turns away to get correct values. Don´t know the reazon of why if i use same dimensions, same coil form, same wire, i don´t get the results of 21 ohms and 6.7 ohms has Ivconic. No dubs on this, everything was cheked and is ok. But my mesures are still diferent. So for that i ll made the coils to match correct values, and this means for example for my tx coil only 85 turns instead of 120.
120 turns give me 11.43 mH and 30.2 ohms, not correct, double cheked with diferent instruments and results are the same. Also if i calculate the values with software, gave me also very close to 85 turns ( see my previus report).

Perhaps this troubles, it´s a very nice detector to experiment and learn.

Best regards
Nelson

Hi Max, yes i think this is the hardest part of the project.
Anyway i ll keep traing until i get good results.
Yes i agree in this case that inductance is not to important. I just discover that if you made the coil to match impedance btw 19 and 22 ohms, you are geting closer and then if you mesure inductance you get the correct values (21.6 ohms and 5.9 mH for TX coil). Now why this detector must mach 19 to 22 ohms of resistance?
Has a hamradio hobbist, i learn that most of radiotransivers use 50 ohms of impedance, so antenns must match this impedance. Is the principle of adjusting coils the same has used for antennas.
Thanks Max and friends.
Best regards
Nelson

[Max]

Max,
When I try to null with multimeter and conect only TX without shields THIS NASTY SOUND IS STILL THERE!!!
Its look like I reach right value!
Can I try now just to conect two RX windings start and end point to RX place on PCB just to test?
Or this is not good idea?
Thanks

Hi,
disconnect speaker to avoid noise during nulling...
then null as well as you can: use15nF cap and 1Kohm resistor.
Try to reach few mV of amplitude (ac).

Yes then connect rx back to pcb and test with speaker too.

Best regards,
Max

[Max]

Max, have you tried any GS coils? HOw where your experiencies?
Can you post your coils details to compare my expirencies with you.
Now i m working on the TX coils, same has Ivconic, but i ll have to take turns away to get correct values. Don´t know the reazon of why if i use same dimensions, same coil form, same wire, i don´t get the results of 21 ohms and 6.7 ohms has Ivconic. No dubs on this, everything was cheked and is ok. But my mesures are still diferent. So for that i ll made the coils to match correct values, and this means for example for my tx coil only 85 turns instead of 120.
120 turns give me 11.43 mH and 30.2 ohms, not correct, double cheked with diferent instruments and results are the same. Also if i calculate the values with software, gave me also very close to 85 turns ( see my previus report).

Perhaps this troubles, it´s a very nice detector to experiment and learn.

Best regards
Nelson

Hi Nelson,
I've made DD22 and concentric round 8''... then also buy a 9x8 original coil.

On DD I think you must have something different from him if you get so different number of turns.

Maybe wire ???

Best regards,
Max

[ivconic]

Calculations?

Wow! How many posts here, in one day??? I need some time to read all and than to reply here...
But only short note for Nelson!

Nelson, as old radioamateur, i remeber (although misty) that you can not use those calculations for large coils...It is not same thing.
Formulas are valid only up to some diammeter (dont remeber which).
Oh, yes, you can input any value in calculations but you will get impossible results, not accurate at all. Check with some radio amateur at your place...
Most of formulas and calculations available on .net are for coil,chokes,inductances mostly used in radio designs, in most cases small sized coils...
There must be some abbreviation factor included when calculating unusuall coils with unusuall sizes.
So far as i know THERE IS NOT NEITHER ONE PROPER FORMULA for MD coil calculations....Strange but true!
Thats why all think that there is some "secret" about coils for MD. There is not....
Best way to know coil inductance is to wound it and than measure with accurate inductance meter....later to do some corrections...
I am telling this cose i also tried so many times with various formulas and neither one gave valid results.
I even reassembled one original White's coil, counted windings and compare all collected data with results got from several formulas - neither one justified experience with original coil???
Know what i mean?

Another thing;

I am big donkey!!! Sorry,sorry,sorry !!! Sorry to all members here!

Outer diammeter is 28cm! Inner diammeter is 26.8cm !!!!!!
I just realized that!? In all hurry and hush to post here some concrete stuff i measured diammeter without thinking....I could swear on 28cm!!!!

Just few moments ago, reading your complains i decided to measure all again.....!!!


Sorry,sorry,sorry !!!! It was not intended! Sorry!

[ivconic]

.

Huh!
I have strong need to explain this muss more...
Remember when i talked about coil housings? I noted that excellent
coil housing can be record holder from old turntable....So!
I founded one with diammeter of 28cm....Sheesh!!!!
All the time i had those 28cm on my mind! Even when preparing
that wooden platform for coil wounding....Redraw recold holder on
platform with pen, substracted approx. 1cm and draw another-smaller
circle to drill holes for small wooden poles...again without
any measuring. I done this so many times, prepared so many "platforms"
for various coils....you cant imagine!
It became stupid,vapid routine for me.....Later i done all what
decribed here (posted photos) - again without measurments - who need
those any more?!
And finally tottally forgot starting measurements! All the time i was
secured that 28cm is "the diammeter"...!?
I wouldnt pay any attention more on it (already have prepared platform
for next coils) if you werent complained here and posted your doubts...
In some way I HAVE TO THANK YOU A LOT NELSON for reminding me...Heh!
Obvious evidence that nobody here is infallible! Especially me!
I made so many simillar mistakes here - no wonder some people always
checking my posts!
Myst be that funny hat i am wearing?
So, SORRY again. I caused you a lot of work!
Anyway, come to think, even if you correct all..still it is big
difference in resistance you got with your coil?
It is some 8-9 ohms difference between my and your coil? Is it
possible? 1cm diammeter difference cant cause such big difference
in resistances? Or it can? Only way is to check by making another coil
and measure it.
To do that fast, you have to wound coil only, without applying farady
cage and all the tapes over....Do it just for comparsion and let me know.
You have to gain between 20-22 ohms...

Do not have doubts in wire gauge - i am sure about it. Already
checked many times.

Nelson...wish you succes. I am glad to see that your detector is
working good.
Next thing you'll wish - is to make it "Light", just as i done.
You'll relized that after spending week or two on the field with it.
It is so good in plain Disc mode, who need "Notch" any more?

Regards! Keep us informed...

TikTak, you'll get it! Sooner or later it will work! Do as Max told you.
I think there is not any mistake in your detector. Just leave it in
DISC mode (All Metal with full sense can cause "singing" as Max told you)
First null the coil - later do the rest...

[Shahab]

Hi Shahab,
think that we treated before... anyway I use with success this DD.
Outer diameter of DD coil = 22cm
Wire diameter/gauge 0.25mm(30AWG) measured without varnish (0.28 with varnish)
Tx turns = 120
Rx turns = 120 (but you maybe would use a bit more 125-135)
Resistance of both around 22ohm (must be from 18 to 24ohm)

Null as well as you can... read previous posts for how to.

Then test before without shields and see how it goes... if you get e.g. 25cm for 1cm coin you are on the right way. Then add spiral of foil... as shield as described.
Fix everything in housing using epoxy.

I can detect 1eur coin at 30cm underground with that coil and bandidoII. Coil would be even better on GS.

When you use it on real field make first a good geb tuning using trimpot on pcb... you haven't to see any audio change when rising or lowering the coil to soil from e.g. 30cm to 10cm... but you have to rise and lowering it fast not slowly. In test bench is better avoid messing with ground balance too much... just use a ferrite round core... you must set up trimpot to ignore it at 5cm from center of coil. You need detector doesn't sound with it... then exercize with disc/notch. For an idea look at bandido user manual... GS isn't much different but as Notch that bandido haven't.

Then go to one good test field and play for 2-3 hours... and you'll master the beast!

Best regards,
Max

Only i can say you "THANKS A LOT..."

[Shahab]

Hi Ivconic.I wish you are fine & happy.

In real your posts from first until now were very very useful.I wish you

continue...

But i want to say a thing you...I wish...

You died me with your 28cm coils.Please...Please...Please...write right & true

features about it...