Surf pi coil ?????

[AndyGB]

I'm going to start making a coil for a Surf p.i tomorrow. I want to make a mono coil of around 225mm diameter. Can anyone tell me how many turns of .5mm enamel copper wire I should use and can I use RG8 or RG58 coax cable to join coil to circuit board.



I know there are lots of threads on this subject but keep finding different information


AndyG

[Qiaozhi]

I'm going to start making a coil for a Surf p.i tomorrow. I want to make a mono coil of around 225mm diameter. Can anyone tell me how many turns of .5mm enamel copper wire I should use and can I use RG8 or RG58 coax cable to join coil to circuit board.



I know there are lots of threads on this subject but keep finding different information


AndyG

RG58 is a good choice for the cable.
You can use this coil calculator to get the number of turns for the inductance you require.

[WM6]

I know there are lots of threads on this subject but keep finding different information

AndyG

Mean it is not so critical. For 225mm coil you need 25 turns.

Better to build spiral shape coil with outer diameter 225mm and follow to get inductance of 300uH.

[AndyGB]

Thanks for the information, I'll be going with a spiral coil then!

Cheers,

Andy

[chocochips]

RG58 is a good choice for the cable.
You can use this coil calculator to get the number of turns for the inductance you require.

Hello Qiaozhi,

Can I have the formula to get the inductance please?
There are so many formulas to calculate inductance and i do not know which one is the suitable one.

Thank you!

[Qiaozhi]

Hello Qiaozhi,

Can I have the formula to get the inductance please?
There are so many formulas to calculate inductance and i do not know which one is the suitable one.

Thank you!

Please use the calculator attached to this post ->
http://www.geotech1.com/forums/showp...78&postcount=2

You can see the formula in the javascript file.

[chocochips]

Please use the calculator attached to this post ->
http://www.geotech1.com/forums/showp...78&postcount=2

You can see the formula in the javascript file.

The formula given in the javascript is surprisingly complicated >.>

And, can I know where you get the formula from?

Thanks!

[DigginOlz]

Hi Everyone,

This is my first post, I am a total noob and have only basic electronics skills. I have a VLF detector at present however due to being so close to salt-water beaches would like to attempt the surf PI kit (which just arrived last week).

Before I kick off I like to have all the information in front of me and have a clear plan of attack so have been researching coils and shielding and have realised rather quickly that there is much science in this subject that is way over my head. While I'm keen to learn more, for now I just want to get the job done - so the "dual coil spun around the CD cannister 30 times" design a.k.a tesla coil design does it for me. What I am totally confused about is how to cover the coil and attach the hinge and what to join the wires with to assure a water-tight seal.... and shielding / paint etc.. what is best for the beach and what does this shielding achieve??

Are there detailed instructions on how to go about fashioning the coil for the surf PI including electrical connections, shielding and mounting hardware etc.. ?

[DigginOlz]

Surely someone has an outstanding experience with building a coil for the silverdog surf 1.2 kit. I would like to know more about mounting hardware (how to connect the coil in a waterproof manner) and what to cover the coil with. Am I missing some other fundamental stuff which is why no-one is replying?? About all I can find is how to wind a pair of wires around an empty CD cannister 30 times. How do you mount and connect the coil in a water-tight manner without the coil detecting the hardware you use to attach it with?? Do you use water-proof glands, BNC connectors etc.. ??

[TH'r]

Razorback Coils made me a very nice 5 1/2" custom coil for my modified Surf Pi Pro. Check with them, they might save you much trouble.

[DigginOlz]

Sir, you are a legend - and I now have a new site to haunt If Razorback comes through I will be back to post an update for anyone else who is building the same kit. Many thanks TH'r !

[baum7154]

If you want to optimize your coil for finding small gold I'd avoid the use of RG-8 or RG-58 as both have about 26pf of capacitance per foot and capacitance is the enemy of coil speed. RG-62U has 13.5 pf of capacitance per foot and there are other options such as a twisted pair with thick PTFE aka Teflon insulation that can be better still. I would be interested to see what feed line Razorback is using.

Good Luck!

Dan

[Geo]

Hello.
I want to make a coil for Surf_PI for underwater detecting.
It must work at 25..30 m depth (2.5 .. 3 atm pressure). I am not sure if RG-58 will work perfect at this depth or the pressure will destroy it.
Does anyone has the experience???

Regards

[bernte_one]

hello geo

i dont believe that a cable is destroyed by the water pressure

[Geo]

hello geo

i dont believe that a cable is destroyed by the water pressure

Hi.
Before long time i tried a "fat" microphone cable at 4..5 m depth in the water and it shorting.
RG58 is more resistant than the microphone cable, but i want to be sure before i"ll try it at 25+ m depth.