TESORO GOLDEN SABRE

[tiktak]

Hello,

Hello,
Did anyone have data for DD 45cm?
Any sugestions?
I see that Minelab Relic Halk is now selling with such?
This is hugh thing should reach very deep!

[Aziz]

Best CC-coil should not compensate its magnetic field. In this case, we have only one TX-coil (Radius R3) and two RX-Coils (N1, R1, N2, R2).
N1 = number of turns for RX1
R1 = radius of RX1
N2 = number of turns for RX2
R2 = radius of RX2
R3 = radius of TX-coil
Balance is made by R1 <= R3, R2 > R3 with appropriate radius and number of turns N1,N2 and the RX coils are connected in serial with opposing winding directions (differential mode). Remember,

the total Φ(N1,R1,N2,R2) gets =0 over the total flux area of the RX-coils (A).
Is anyone interested on experimenting with such a CC-coil? I can provide all the needed parameters.
Aziz

[Aziz]

What we need is a magnetic field density/strength profile for CC-coil like below:

[Aziz]

The fact of the CC-Coils (concentric coplanar) is, that they have to compensate the magnetic field flux (Φ) inside the flux area of the RX coil (A).



Otherwise, it wouldn't be balanced. This causes decrease of the magnetic field density and strength (B, H) on the center position of the coil compared to DD or OO coils. Magnetic fields of DD or OO coils need not to be compensated. So the fully possible magnetic field density can arrive the target and maximize the induction effects.


(Uind=induced voltage, n=number of windings)

What we have to do is, minimizing the compensation magnetic field over the center of the CC-coils. I am working on this and probably I found an ideal solution for this. I will know in few month, whether such a CC-coil is possible. I am still working on the coil software and it is pitty, that I have to wait until some important implementations are done.

Aziz

[ivconic]

To all other members here;
do not be confused with my various reports on coils i made. All of those are excellent if made properly. Differences are minor, less than 2-3%.
I do have much spare time to experiment so i made a lot of coils all types.
Doesnt mean that i left one type and start with other cose not satisfied with previous. It is only cose i do like to experiment.
BTW this forum is just about that; to experiment and experiment. By experimenting and making a lot of things...man can only learn more, stay in good shape and "updated" with facts.
Knowledge is a sort of discipline. If exercised on daily bases - good. If left as it was - very bad!
In the past i was pretty succesfull Cobol programmer. I havent done anything for 10 and more years. Now, these days, listing my old codes, i feel as totall ignorant! Nothing to understand there!?! Was it me? Was i written that code??? Sheeesh! So, knowledge is discipline for sure!

[Fred]

Hi Ivconic,
Thanks for info !.
I had good depth with DD, but i found a bit less precise and less stable than with my omega.But if you say it works OK then i will try to build a new one.I want to search where there is rocks etc, so i will try a smaller one, around 20-22 cm.I will use this 0.25mm teflon wire.
Good luck!
Regards,
Fred.

[ivconic]

Ok Ivconic, thanks ,
You died making them?
But what about detection distance? i don´t like very much the beahaviour of the DD, really omega and CC seem to be more reliable in several aspects, so i would like to try a good one of those.
As i said, for CC i was able to achieve a good null, but inductance was bad, so was the frequency,because of influence of bucking coil.This would not be so bad with omega i think.
regards,
Fred.

Yes, at the time i had much problems to achieve good null. But after much of efforts, somehow i managed to make it to detect single coin (2cm) at 27-28cm in air. Oh yes coil was 24cm diammeter.
Inductance-frequency??? Than you should try to adjust proper frequency changing capacitor in oscillator; try to replace 0.022 with 0.027,0.033 or 0.039 instead, and than measure frequency. Leave RX unchanged.
I dont think you made proper DD coils since you are not satisfied with it? DD coils work excellent with TGSL!
Pinpointing small object is easy; move fast coil east-west and north-south over the soil surface and you will easilly distinguish the very center of burried object.
DD coil is superior over cc considering depths. Also very small coins are easilly detected with TGS&DD coil. Only! Only...when prospecting very small silver coins, you must go bit slower with coil sweeps and try to hold coil just a few mm's over soil surface...almost touching it with coil.
From earlier experiences, good prospector must know character of visited terrain, meaning you must know what to expect on that terrain. Usually i do know in advance if i can expect to find small silver or gold coins on some terrain. So according to that presumption i do use proper searching technique. On leveled, unknown terrains i do walk very fast with wide sweeps. On hills with a lot of bushes arround i do walk slowly, short, narrow sweeps...etc.etc...
I tell you; dd coils doesnt have important disadvantages comparing cc or omega coils. Trust me on that. Besides...if you still have doubts in my words...just look Minelab best coils; all DD!
Regards!

P.S.
Minelab is still "great daddy" in metal detecting world, so i almost always use their products as sort of references. Although White's is also "great daddy" too, yet they mostly using cc coils with their products.
But, latest 45cm coil for DFX is DD !?!?!?
I think both of mentioned manufacturers are just used to make type of coils they adopted as best for their detectors, meaning again - no rule at all! Anything will do if made properly...Plain truth!

[Aziz]

Hi Aziz,
Here are 2 calculator.One unfortunately in French , .xls file,the other from elektor, looks quite precise.you have to extract files to the same folder.
regards,
Fred.

Hi Fred,

many thanks for the calculator. I will test them tomorrow.
Nevertheless, I have to measure physically the coils to check the coil software (I am surely be suspected of my calculated results). For this purpose, I want to buy a new multi-meter with more accuracy tomorrow. Then the same procedure as usual - coil winding.

Regards,
Aziz

[Fred]

If anyone has a better online/offline inductivitiy calculator, please let me know.Aziz

Hi Aziz,
Here are 2 calculator.One unfortunately in French , .xls file,the other from elektor, looks quite precise.you have to extract files to the same folder.
regards,
Fred.

[Fred]

Make approx. 90 turns for TX and continue with f.b. in oposite direction untill adjust to good null.
C.C. coils...hmmm!? I died making simillar for Classic III, at the time.
Good null...substract 2-3 windings from F.B. at the end and use those as nulling loop, randomly placing it inside coil housing and monitoring induced voltage at RX, to fine redjust balance. Would be good to monitor phase behavior also.
Regards!

Ok Ivconic, thanks ,
You died making them?
But what about detection distance? i don´t like very much the beahaviour of the DD, really omega and CC seem to be more reliable in several aspects, so i would like to try a good one of those.
As i said, for CC i was able to achieve a good null, but inductance was bad, so was the frequency,because of influence of bucking coil.This would not be so bad with omega i think.
regards,
Fred.

[ivconic]

Hi Ivconic,
I have been experimenting with a cc coil for the TGS: i used 20cm TX, 107 turns gives 6mH , 0.25mm teflon islolated silver plated wire.
For RX around 160 turns 12cm same wire to give 6.5mH.
Then bucking coil was 36 turns around Rx coil, wich gave an excellent nulling.
Behaviour of the coil was very good too,disc, ground, EXCEPT RANGE , wich was quite bad.
My conclusion is that the bucking coil modifies too much the total inductance of both coils, it is too dificult to correctly tune them.
The bucking coil make the total inductance of the TX one go to 5.1 mH, but to increase nº of turns we should also modify the bucking nº of turns, wich in turn changes again inductances.A hell.
Have you been more succesfull with the omega ?
I would like to build a better one, around 22cm diameter.
Regards,
Fred.

Make approx. 90 turns for TX and continue with f.b. in oposite direction untill adjust to good null.
C.C. coils...hmmm!? I died making simillar for Classic III, at the time.
Good null...substract 2-3 windings from F.B. at the end and use those as nulling loop, randomly placing it inside coil housing and monitoring induced voltage at RX, to fine redjust balance. Would be good to monitor phase behavior also.
Regards!

[Aziz]

Hi Aziz,
No calculator: I wound more turns, then take out untill i get right inductance.
Of course inductance increase when you tight up te wires with tape, but with some experience it´s OK.For example 5.8mh when thightened will give around 6 ...
Radius is 10cm for TX coil (20cm diameter),6cm for RX.
Regards,
Fred.

BTW, how do you know mu :
m(relative) = m(material) / m(air)
where: m(air) = 1.256 x 10-6 H/m
What is mu of material?

Hi Fred,

thanks for quick reply.

µr (relative permeability) is 1.0 for air. Just enter 1.0 in the web site mentioned above. µ = µ0 * µr, µ0 = 4*PI*10^-7 (=absolute permeability). µ is used for the Magnetic Flux Density (B-Field) calculation from Magnetic Field Strength (H-Field). B = µ*H = µ0*µr*H.

I am a little bit confused about the parameter a. Mean this the wire radius or the bunch of the stranded wires radius. I don't know yet.
If anyone has a better online/offline inductivitiy calculator, please let me know.

I have to check the algorithms for inductivity and induction calculations.
Regards,
Aziz

[Fred]

Hi Fred,

which inductive calculator do you use?
I found this site: http://emclab.mst.edu/inductance/circular.html
Which radius of the windings do you have? I mean not the wire diameter but the total 107 windings diameter (not 20 cm).

Hi Aziz,
No calculator: I wound more turns, then take out untill i get right inductance.
Of course inductance increase when you tight up te wires with tape, but with some experience it´s OK.For example 5.8mh when thightened will give around 6 ...
Radius is 10cm for TX coil (20cm diameter),6cm for RX.
Regards,
Fred.

BTW, how do you know mu :
m(relative) = m(material) / m(air)
where: m(air) = 1.256 x 10-6 H/m
What is mu of material?

[Aziz]

Hi Ivconic,
I have been experimenting with a cc coil for the TGS: i used 20cm TX, 107 turns gives 6mH , 0.25mm teflon islolated silver plated wire.
For RX around 160 turns 12cm same wire to give 6.5mH.
Then bucking coil was 36 turns around Rx coil, wich gave an excellent nulling.
Behaviour of the coil was very good too,disc, ground, EXCEPT RANGE , wich was quite bad.
My conclusion is that the bucking coil modifies too much the total inductance of both coils, it is too dificult to correctly tune them.
The bucking coil make the total inductance of the TX one go to 5.1 mH, but to increase nº of turns we should also modify the bucking nº of turns, wich in turn changes again inductances.A hell.
Have you been more succesfull with the omega ?
I would like to build a better one, around 22cm diameter.
Regards,
Fred.

Hi Fred,

which inductive calculator do you use?
I found this site: http://emclab.mst.edu/inductance/circular.html
Which radius of the windings do you have? I mean not the wire diameter but the total 107 windings diameter (not 20 cm).

[Fred]

Hi Ivconic,
I have been experimenting with a cc coil for the TGS: i used 20cm TX, 107 turns gives 6mH , 0.25mm teflon islolated silver plated wire.
For RX around 160 turns 12cm same wire to give 6.5mH.
Then bucking coil was 36 turns around Rx coil, wich gave an excellent nulling.
Behaviour of the coil was very good too,disc, ground, EXCEPT RANGE , wich was quite bad.
My conclusion is that the bucking coil modifies too much the total inductance of both coils, it is too dificult to correctly tune them.
The bucking coil make the total inductance of the TX one go to 5.1 mH, but to increase nº of turns we should also modify the bucking nº of turns, wich in turn changes again inductances.A hell.
Have you been more succesfull with the omega ?
I would like to build a better one, around 22cm diameter.
Regards,
Fred.