TEFLON MULTI STRAND WIRE QUESTION

[daverave]

im thinking of making a lighter faster coil and i saw some teflon multi strand wire...they were both 22 awg 7 & 18 strand....is 22swg the best for fast pi coil also how many strands are best ????

[baum7154]

I have used 24 and 26AWG Teflon wire and they work fine. My personal opinion is that 22 AWG is a bit too large.. Large r wire = greater capacitance. In addition try to get 600 volt insulation as thicker insulation =l ess capacitance. See my CHANCE COIL BUILD thread under COILS.
More strands are better but I have used 7 strand with success.


Dan

[daverave]

i only want to use the coil on the beach and not nugget hunting...is multi strand teflon wire over kill for the beach and will it produce ground effect from the wet sand ???? i noticed you mentioned the chance coil...i was going to make a chance pi detector but i understand it needs 2 coils to get any iron discrimination which put me off a little....as i like mono coils which are easy to make....also can you get deep targets with a chance pi ?????

[golfnut]

teflon has a fairly low dielectric constant, abiut 2, which helps make a coil with lower inter winding capacitance. So it can shift charge fast. Which is what you want,

S

[baum7154]

i only want to use the coil on the beach and not nugget hunting...is multi strand teflon wire over kill for the beach and will it produce ground effect from the wet sand ???? i noticed you mentioned the chance coil...i was going to make a chance pi detector but i understand it needs 2 coils to get any iron discrimination which put me off a little....as i like mono coils which are easy to make....also can you get deep targets with a chance pi ?????

Well if you are on the beach you might want to go as low as 10us in some cases so a fast coil might be a help. I don't think a multi strand teflon insulated coil is a mistake at all. I seek small gold with an 8" coil specially wound in the pattern shown in the CHANCE PI COIL thread. I don't know if my coil would work on the saltwater beach but it does decay in 6us and it is quiet over the mineralized soil I hunt. Because of its geometry it self shields and does not require a separate shield for the soils I work.

CHANCE does not NEED 2 coils to discriminate iron but it would possibly be improved with a two coil setup, don't know, have not tried it. With a mono coil it will see small iron and at low receive signal level (below 6 units)it will jump from left to right on the VDI scale. As signal strength increases the VDI begins to settle on the IRON end of the scale and the audio output will have increasingly greater high pitched notes indicating the lron end of the audio response. These two things in combination give an operator two good clues that a target is likely to be iron. Gold is always a solid low tone and always on the left end of the scale. Silver and copper are very high pitched tones and always on the right end of the scale. My fast 8" monocoil sees a 1/4" X 1/4" piece of aluminum can at about 2" and it appears on the left end of the VDI scale with a low tone, the same as gold . This would not be possible without the Teflon/PTFE stranded coil wire.

As far as depth it depends on what you consider deep. How big of a target are you typically seeking and what is it made of? I can tell you that the CHANCE with the 8" coil will see a 4.5 grain 14kt gold head (meant to hold a 4 mm stone) in soil at my test site at a depth of 4.5". I don't know if that qualifies as deep. I have not tried larger coils that you would typically expect to use for deeper hunting. I have just modified my CHANCE with a 2 stage amp to allow it to see small gold better and plan to take it out tomorrow to see what it will do. Will report the results in the CHANCE PI BUILD thread.

Hope this helps,

Dan

[daverave]

cheers for the reply....maybe i will try stranded wire...i saw some 28 swg 7 strand which i guess would work...i may try and build the chance but at present i want to build a light weight good depth machine...my first detector i made ive just modified and im getting around 20" on a 9ct wedding band ring...but some of the targets are just too deep and i cannot dig them...ive decided to use the pulse machine for both dry and wet sand and i find digging some small iron is no big deal anymore.

[6666]

my first detector i made ive just modified and im getting around 20" on a 9ct wedding band ring.

Would you mind sharing your mods please ?

[daverave]

my mods are simple in that i just increased the gain of the dc amp and i have shielded the pcb in aluminium foil and its given me several more inches of depth....the machine is better for depth but i cannot dig some of the deep holes

[baum7154]

cheers for the reply....maybe i will try stranded wire...i saw some 28 swg 7 strand which i guess would work...i may try and build the chance but at present i want to build a light weight good depth machine...my first detector i made ive just modified and im getting around 20" on a 9ct wedding band ring...but some of the targets are just too deep and i cannot dig them...ive decided to use the pulse machine for both dry and wet sand and i find digging some small iron is no big deal anymore.

Very good depth! What size of a coil are you using? What is the weight/dimension of the wedding band? What type is the detector?

The larger gauges of Teflon coil wire not only add more capacitance but also create more noticeable effects of eddy currents as they are almost all silver plated. Once again, smaller gauges are better for the normal PI fast coils. I think that 28 - 30 awg may be the smallest practical size. The main drawback of the small wire gauges is that the coil resistance may get a bit high for some high power applications.

Dan

[daverave]

my coil is 12" across.....and my ring is 4g 9ct gold....and my detector is a surf pi which ive modified to higher frequency....im now looking at some 28 awg 7 strand teflon wire and maybe i will go for this and experiment...but i can only get 300v rated wire !!! its ok making deep detectors but hard to dig the holes....a friend of mine who is like a professional detectorist tried digging some of the holes i could not dig and even he was having a hard time and had to leave them....but i like the challenge of making a really deep detector with low current consumption.

[geoscash1]

daverave, Can you post some pics and info on your mods and/or post a video..

[6666]

Thanks Dave for the mod info, its funny we all want a detector that goes deep but we hate digging deep holes in the surf ( I do), next time you are at the beach would you be interested in trying a relative test ?

My standard comparison test for the beach is get a soft drink can (coke) crush it vertically , and bury it at 20 inches in wet sand.
I would be interested in your results if you try it,
Cheers

[johnandles]

[QUOTE=6666;190357]

My standard comparison test for the beach is get a soft drink can (coke) crush it vertically , and bury it at 20 inches in wet sand.


So, its you who leaves all those crushed cans buried for me to get all exited about....lol
Cheers
John

[golfnut]

surf pi and a ring in wet sand... did you mean 20cm

[daverave]

20 inches in air test