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

[junkhunter]

i do it by sound do have a coil calculator . ok dropped my coil wire on NE5534P today blew up got a spare also my new coil is 25 turns 9 inches by 12 inches 0.63 wire was picking up a tobacco can at about 70 cm blew me away . i have to do this before i can do a post a post they have told me .stuffed around with delay and other pot still dosent pick up a light gold chain. my garret 250 picks up needle in a hay stack also running a 9.6v recharge pack works better then 8x1.5 v battery dont know why . want to do a post to show you my under water metal detector all aluminium and under water head phones for you to see and how to build

[junkhunter]

thinking about changing the pot value any ideas not happy with the pi surf 1.2 worked first time .any mods availabe i learn at looking at pictures . if you guys have any post them

[junkhunter]

the mods dont want me to post a url but here it is http://coil32.net/online-calculators...esla-coil.html http://coil32.net/online-calculators...esla-coil.html

[kenny444]

Hello junkhunter, the coil calculator you link to is a flat wound coil, have you see this? https://www.youtube.com/watch?v=EWwWE3YpEqA.

[junkhunter]

yer this guy is fake wont help you . go for it hes a **** (********)

[junkhunter]

im not smart but i am good with my hands i like pictures allright . so give me some mods guys i have a under water viper clone cost me $118.au after they posted it from england 4 days fed x it didnt work so i got it half price every *****es about these metal detectors . ok i found they leak and have bad dry joints on the board . fixed that fu** me worked good again . then leaked agian ok do it again replace parts . i was picking up metal 8 inches down the other day . better than the surf pi 1.2 $60 surf pi silver dog what crap sorry

[Sean_Goddard]

If you are using say Raychem type 44 or 56 wire in 24 AWG then there are two ways to wind ultra fast coils.

1) wind basket weave flat coil and use 100lb FLOUROCARBON fishing line along side, that is wind TWO lines side by side one wire the other fishing line.

2) wind TWO interspersed coils side by side, as above but use one as the TX the other as the RX.

I did this and I got two awesome 5us coils for my homebrew PI, this thing is so sensitive to small gold it is scary.

[CAS]

1) wind basket weave flat coil and use 100lb FLOUROCARBON fishing line along side, that is wind TWO lines side by side one wire the other fishing line.

Why do you use the fishing line? Is it to put more space between the windings?

[edwalti]

What does the space between the winding coil do?

[CAS]

Putting space between the windings would decrease capacitance and therefore make a faster coil - but I am not sure if thats the reason he is using the line. Hence the reason I asked. I am just about to wind a new coil so i am really interested in the answer.

[golfnut]

What does the space between the winding coil do?

lots of dielectric material packed around the windings provides a mechanism to hold charge in the coil in the form of distributed capacitance between adjacent windings.


All of these coils are not just L they have some shunt C also - at some frequency they resonate.

If there is more C for a given L then the frequency is lower and and so the decay time is long


Reducing the C pushes the resonant frequency out - i.e. makes the coil faster to react, so recovery after the pulse to the first rebound is quicker. So you can sample earlier to see smaller things

having gaps between the windings helps


You can increase speed by reducing the the L also by using litz which has a lower L per unit length. _ This smaller L would give less energy storage though, to compensate you would need more current. (1/2 Li sqrd ... joules )

[golfnut]

Sorry CAS we went together. Why you up so early ??

[CAS]

Sorry CAS we went together. Why you up so early ??

Been out fishing this morning but am normally up early for work. Besides its the best part of the day.

[geoscash1]

Can you post some pics of your coil or a video of it in action?
I'd like to see the coil and what you mean by "2 interspersed coils side by side"

If you are using say Raychem type 44 or 56 wire in 24 AWG then there are two ways to wind ultra fast coils.

1) wind basket weave flat coil and use 100lb FLOUROCARBON fishing line along side, that is wind TWO lines side by side one wire the other fishing line.

2) wind TWO interspersed coils side by side, as above but use one as the TX the other as the RX.

I did this and I got two awesome 5us coils for my homebrew PI, this thing is so sensitive to small gold it is scary.

[junkhunter]

here is my underwater surf 1.2 finished