Tube coil

[ivconic]

To all PI experts here on forum,
there is pretty concrete problem i have to solve.
Have Barracuda or Surfmaster as PI detector, need special coil for special tasks.
Coil is supposed to be mounted in PVC pipe.
I need highest depths or distances possible to achieve with such coil.
Coil supposed to be involved in hole in soil and lowered as much as cable allows (2.5 meters cable is planned).
It doesn't really matter from which side coil will be more sensitive , but what is important and desirable is to achieve highest possible detection distance on small items such as coins and similar.
So i tried to make coil as on example "B", but couldn't achieved more distances than 5-6cm on single coin... not satisfied.
Now i am thinking to try example "A" coil setup.
Any suggestions? Hints? Experiences?

[DOOLEY]

HELLO IVCONIC ,

my opinion , for what it's worth as small fry ,

can i asume you want most sensitivity from the side ?
and you will be dropping it down a hole drilled in the ground ?

option B no good , sensitivity up and down ,

option A good , but no allround "omnidirectional" sensitivity ,
poss 2 oval coils at 90 deg ??
to get both directions ??

how about an oval flat plannar coil wrapped around pipe perfectly so outer perimeter only touches when fully wrapped round the pipe , pipe will be plastic , so it will "see through" so all sides will be as sensitive as the rest , but most sensitive in the center of coil for pin pointing but still sensitive in all directions ??

then cover for protection against getting rubbed through with repeated use.

[DOOLEY]

no , hang on a second , scrap that oval flat plannar coil wrapped round idea ,
it will cancel out as it's wrapped round.

poss best stick to oval coils , but at 90 deg to each other ,

or single oval , but instead of lowering on cable , lower using rigid rod , so you can turn it , and look all around the hole , then you can identify which side of the hole to dig ,but , as it will see through pipe signal could be half a turn away ,

could you have not asked an easyer question ??

[ivconic]

"..and you will be dropping it down a hole drilled in the ground ?.."

Yes!

"...or single oval.."

Yes, it must be single (mono), because i intend to use it with simple PI (Barracuda or SurfPi).
Can you describe your suggestion a bit more detailed?
Can you draw a sketch of it?

[bernte_one]

maybe your plan b but with two coils

take it from the scientists

http://www.geophysik.tu-freiberg.de/..._induktion.pdf

graphic on side 3 at surf pi you can use a tx and a rx coil but i dont know if they have to be balanced or how it schould work maybe over the distance from coils to each other ?

sorry im a noob on this area but use tx and rx seams to makes sens in a small hole

[ivconic]

maybe your plan b but with two coils

take it from the scientists

http://www.geophysik.tu-freiberg.de/..._induktion.pdf

graphic on side 3 at surf pi you can use a tx and a rx coil but i dont know if they have to be balanced or how it schould work maybe over the distance from coils to each other ?

sorry im a noob on this area but use tx and rx seams to makes sens in a small hole

Interesting indeed!

[ApBerg]

Hello Ivica,
A long ..long... time ago I have made that coils, not very sensitive as I remember.
In some old note's I found that using 2 ferrite rods from 10 cm long and placed them in series’ gave the 'best' results, some space between them.... but I was not very glad with the results...

Best regards.

Ap

[ivconic]

Thanks!
I also made something similar in the past.
Also not satisfied with results.
I would be happy to achieve 12-15cm detection distance for a single coin, seems tough task.
Must try first A setup - than maybe i will give up!

[ApBerg]

Hello Ivica,
A long ..long... time ago I have made that coils, not very sensitive as I remember.
In some old note's I found that using 2 ferrite rods from 10 cm long and placed them in series’ gave the 'best' results, some space between them.... but I was not very glad with the results...

Best regards.

Ap

If you wind the coils on a pvc tube that fits the ferrite rod so that you can shift the rod than you can adjust the uH s'...

[ivconic]

I need some 0.3-0.4mH, as i had nice performances with such coil and Barra.
Will make it today and see.

[ApBerg]

Thanks!
I also made something similar in the past.
Also not satisfied with results.
I would be happy to achieve 12-15cm detection distance for a single coin, seems tough task.
Must try first A setup - than maybe i will give up!

You need PI ? With VLF results can be round 20 cm from the probe( in air test) .... send you some time ago info ..top secr....!
Use it with your non motion vlf from tesoro.. make the output high volts ca 100v !

Best regards.

Ap

[ivconic]

You need PI ? With VLF results can be round 20 cm from the probe( in air test) .... send you some time ago info ..top secr....!
Use it with your non motion vlf from tesoro.. make the output high volts ca 100v !

Best regards.

Ap

I remember. Tough, because i have so specified demands...
Must be a PI, small and simple.
PVC tube to carry the coil is also MUST with given dimensions... tough task!
Also must be nonmotion, static..

[bernte_one]

nonmotin? ahh like surfpi or bara in pinpoint mode

high output and nonmotion?

have a tiny made from german pulsdetektor forum
has i high output and works with clicking sound
could try out it can post results later
but i will try this b type i hope 10cm are possible

[ApBerg]

Hello Friends,

Well..... have just made some coils again .. made tests with the bara, de results... not bad (for a pinpointer good !)

Made it like the litte drawing, look a few post earlier...made one with 80 turns clockwize result : not good and lots 50 Hz

made one ... 80 turns clockwize and 80 turns counterclockwize... no 50Hz !! and results... not bad !!

make a youtube later today ...

Best regards.

Ap

[Monolith]

"..and you will be dropping it down a hole drilled in the ground ?.."

Yes!

"...or single oval.."

Yes, it must be single (mono), because i intend to use it with simple PI (Barracuda or SurfPi).
Can you describe your suggestion a bit more detailed?
Can you draw a sketch of it?

Hi Iveconic,

I made a quick Spice simulation of Bernte's idea of parallel TX and RX coils. It seems to work.
If you give me the TX voltage, Mosfet ON resistance and Mosfet voltage, I will make the Spice simulation more precise.
Small coils wound on a ferrite core to fit inside the 25mm PVC tube.
With the TX coil few turns of thick wire for high power and the RX many turns of thin wire for high signal amplitude.

Monolith