Please tell us how your wonderful deep penetrating Surf PI 1.2 coil is made.

[kenny444]

Hello and thank you, I am presently working with a board (call it PCB1) and an 8 inch, .5 copper wire coil and sorted out the scope settings, watched the offset move on adjustment, and got a clear sight of the wave form I have, (but I have no reference only Tepco's jpgs) when I am happy with the things I can see, I will move to PCB2 and work from that point using the Teflon coil. The Surf PI 1.2 (which is based on the Whites Surf PI) is supplied with a 390R damping resistor, but the Whites uses a 360R, so I found a 358R in my resistors and dropped that into PCB1, I have seen no ringing with the present set up but will endevour with PCB2 and see what there is. An adjustable damping pot will be set up and tested with PCB2 then I will read the link you sent and when I get myself together I will move onward. I not very well at the moment and may have to delay my efforts for a day or two, if I go quiet I am still here. Really grateful for your assistance, regards. Kenny

[multieagle]

For your review!! And thank you Chet and all for convinceing me to finally try a basket coil out.

[ATTACH]31977[/ATTACH][ATTACH]31978[/ATTACH][ATTACH]31979[/ATTACH]


I just finished this basket coil for my Sm pro kit. I used 30 guage radio shack plastic coated wire.
I used the form provided on the Chance Pi coil thread . It is working the best of any of my coils so far. I am primarially looking for gold sensativity in my coils and use the earing in the pictures as my minimum acceptable target. (earing weighs .5 gram) Before this coil with regular fast coil design I could only get it at 3 inches with a 4 inch coil.

Super suprise when I got it all tuned to my Pi I can now hit the earing at about 4 inches with this 8 x10 basket coil.
I also changed out my 5534 for a max 410 and the differance was huge as far as waveform clarity. I will provide some scope pictures when I get it hooked back up. I removed it to put on my last wrap of teflon.

So here is my improvement to the basket design using small guage single strand wire and every 5 wraps I wrap two layers of teflon tape to increase spacing and dialectric and hopeing to reduce capacitance. Also the tape holds the windings in form on the coil form as the oval shape makes them want to pull out of form on the sharper corners.
I went 20 wraps but had to remove one I tried two but had to put one back 19 works well.

The rock in the pictures is a hematite chunk I use for a ground sample. the coil does pick it up slightly but with audio after you leave the target. And almost providing the boing sound that a vlf does on negitive cold rocks. I can place the sample in the center of the coil and it does not effect my depth. If I use it to shield the nugget I still get the nugget as positve response. This peice of hematite totally overloads my VLF detectors and the ground it came from was undetectable. I am no expert in coils and there may be inhearent problems with this coil I have not had it outside yet so that is still unknown. It does have slight sensativity to my hand so that may be a concearn and i may have to shield it.

Here are some of the depths and I have the sens and threshold almost completly silent, when I get outside Ill be able to crank it up and I cant wait to see
if the depth will be close in the ground.
1/2 gram earring 4 inches
1.2 gram nugget almost 7 inches
silver quarter 7 inches
silver dime 8 plus
nickel 10 plus
2 gram gold ring
10 plus
and these are good responses I can hear with my headphones not on my head but around my neck.
Also as Kt 315 has stated I think this design would lend itself for a dual wrap. notch the tabs in the center and wrap a tx or rx coil over the center coil Im not sure which would be on the inside.
you can bet Ill be playing with that...
Hope this can be of use!!

http://www.geotech1.com/forums/showt...-the-MPP/page1 KRinAZ has some improved Basket weave templates in the last pages.

Has anyone a complete set of instructions for making a Basket Weave Coil? I've made an oval template with 37 slots as per another thread. And looked at the Russian image with English translations. However, when I practice with string, after 15 or so turns, my results look nothing like the images I've seen. What I understand from the Russian image, starting from the top side,you progress 3 slots, on the underside 4 slots, for 5 turns. Is this maintained throughout the 32 +- turns, or is there a change in pattern after 5 turns?

TIA

[6666]

Its not complicated after 5 turns the wire drops into the same slot that you started with , move the wire forward 1 slot push wire through to other side and wind another 5 turns,

The 2nd winding starts on the other side of the former and each time you move 1 slot the next winding starts on opposite side of former.

You move forward 1 slot every 5 turns

just look at my pictures
post #180 onwards http://www.geotech1.com/forums/showt...-PI-coil/page8

[multieagle]

Thank you 6666. I did a search for basket weave coil oval. Should have dropped the "oval"

Regards.

[kt315]

Its not complicated after 5 turns the wire drops into the same slot that you started with , move the wire forward 1 slot push wire through to other side and wind another 5 turns,

The 2nd winding starts on the other side of the former and each time you move 1 slot the next winding starts on opposite side of former.

You move forward 1 slot every 5 turns

just look at my pictures
post #180 onwards http://www.geotech1.com/forums/showt...-PI-coil/page8

this is called 'a transfer on another/following layer'. after you notice a turn goes at a turn its way you have to make the STEP on one slot.

[kt315]

[Silver Dollar]

from the top side,you progress 3 slots, on the underside 4 slots, for 5 turns.

Some pictures might be wrong. You skip 2 slots on top and bottom.
When the wire try's to go back into a slot you already used go forward
one slot, this takes you to the opposite side for the next loop...

[edwalti]

This is my first coil and still is not complete and could use some guidance on final assembly before I encapsulate it in epoxy. I used 26 AWG and nailed 20 or so nails on 7inch circle on board then wound 26 turns, used electrical tape to hold together then bent in a few nails then removed from board. This is where I'm currently at any advice would be appreciated. Thanks, Ed.

[kenny444]

Hello edwalti is this for the Surf PI 1.2? If so then this is "some" of what you need to know, "all coils are different", "the damping resistor on the PCB is an ideal value for and ideal coil" if your coil has approximately 300uH (calculated or measured) impeadance and low resistance, "it will work but not perfectly" Have you read this? http://www.adrianandgenese.com/blogg...rom-a-diy-kit/ connect it up and adjust as instructed. We can move on from there. Kenny

[baum7154]

This is my first coil and still is not complete and could use some guidance on final assembly before I encapsulate it in epoxy. I used 26 AWG and nailed 20 or so nails on 7inch circle on board then wound 26 turns, used electrical tape to hold together then bent in a few nails then removed from board. This is where I'm currently at any advice would be appreciated. Thanks, Ed.

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If you encapsulate the coil in epoxy you will add more capacitance and slow the coil down. Don't flood the coil windings with anything.

Regards

Dan

[junkhunter]

im getting about 6" on 5mm silver coin on a 8 inch coil awg 24 35 turns not that good . going to try a 9inch by 12 inch today same wire

[junkhunter]

i ment to say 15mm australian three pence

[kenny444]

Hi Junkhunter, do you know your measured or calculated uH? the number of windings seems too many, Try one made with 15 or 16 turns. or calculate up to 300uH (There is a link to coil inductance calculator, very kindly added below in the next post, Thanks to George), the number of turns also really needs to be balanced with a matching damping resistor. E.G. I have a 14 inch coil, wound with Teflon coated multi strand wire about 24awg and it is 17.5 turns and its associated damping resistor is R610. Hope all comes together for you.

[Qiaozhi]

(There is a link to coil inductance calculator somewhere)

Coil Calculator

[kenny444]

Thank you for the link, appreciated, I edited the previous post.