How sensitive can a small coil be ?

[Goldfreak]

Don't know much about detectors as my main and most successful prospecting tools have been a humble spoon and screw driver but to those who know, how smaller gold can you detect with a small coil ? Will a 5 inch coil detect half the size gold a 10 inch will down to half the depth ? Will a theoretical 2.5 inch coil be able to detect fly poop size gold ? Sorry if these questions are stupid.

 

[Ridge Runner]

Don't know much about detectors as my main and most successful prospecting tools have been a humble spoon and screw driver but to those who know, how smaller gold can you detect with a small coil ? Will a 5 inch coil detect half the size gold a 10 inch will down to half the depth ? Will a theoretical 2.5 inch coil be able to detect fly poop size gold ? Sorry if these questions are stupid.

On LF "Low Frequency machines like the Whites GMT it runs at 48khz and comes with 5x9/6x10 DD and it can see bits around the size in a grain of brown sugar, I fitted mine up with one of the older Goldmaster II 6x10 Concentric coils and it made it about 3x hotter, which made it about as hot as the Goldbug II, the Goldbug II runs at 71khz and it uses a 6x10 concentric coil also, and they can see bits down to 0.001 grams or less

A good VLF that runs between 12 to 20khz will see your bare hand at about 4 to 6 inches +/- when fitted with the standard Coil, When fitted with a small concentric they will see bits down to 0.006g on average and if there is no EMI right down to 0.003 using a 6" concentric coil,

PI machine coils are starting to make a lot of progress as we have seen from companies like Nugget Finder where they are seeing bits down to 0.02/0.01 grams,

Hope that helps,

John.

This is the sort of thing the GMT can see at about 3" in the Air and around 2" in the Ground.

 

[moeee]

the Goldbug II runs at 71khz and it uses a 6x10 concentric coil also, and they can see bits down to 0.001 grams or less

I find that hard to believe , not saying you are incorrect , but heck , my weight scale has trouble detecting that

 

[Ridge Runner]

the Goldbug II runs at 71khz and it uses a 6x10 concentric coil also, and they can see bits down to 0.001 grams or less

I find that hard to believe , not saying you are incorrect , but heck , my weight scale has trouble detecting that

Well in order to be able to weigh them I had to go to a specialist Scale company and buy a set of scales with a 0.0001oz and 0.001gm read out, That is 4 and 5 digit read out, they only go up to 50 grams but they go down very low where they even weigh your breath.

The Goldbug II will easily hit bits weighing 0.04grains or 0.002 grams. Which is why you see so many prospectors use a plastic scope to find their prize.

 

[Tathradj]

Then you put a sadie coil on a gpx and crank it
up flat out.
try and find it then.
Drives you nuts. ]
There is a lot to coil design and remember that a detector is a transmitter
and a receiver.
The coil is the antenna for both tx and rx with all associated modules tuned
to a very fine knife edge.
the harder you can drive a coil without saturating it, The more sensitive it will be.
In basic, If you have every thing running at resonance and loaded to the right degree,
Your sensitivity will be at max before the machine will over load, ie; saturate.
There are books written on this and what I have out lined is only basic stuff.

 

[Ridge Runner]

the Goldbug II runs at 71khz and it uses a 6x10 concentric coil also, and they can see bits down to 0.001 grams or less

I find that hard to believe , not saying you are incorrect , but heck , my weight scale has trouble detecting that

These are the Scales I bought, but I did the ebay and they all turned out to be junk,

These are the ones I bought.

hope that helps.

https://www.ourweigh.co.uk/pocket-mini-scales/on-balance-ct-250-carat-scale.html

 

[Ridge Runner]

Then you put a sadie coil on a gpx and crank it
up flat out.
try and find it then.
Drives you nuts. ]
There is a lot to coil design and remember that a detector is a transmitter
and a receiver.
The coil is the antenna for both tx and rx with all associated modules tuned
to a very fine knife edge.
the harder you can drive a coil without saturating it, The more sensitive it will be.
In basic, If you have every thing running at resonance and loaded to the right degree,
Your sensitivity will be at max before the machine will over load, ie; saturate.
There are books written on this and what I have out lined is only basic stuff.

Great Answer Tathradj that's where the skill comes in.

Major thumbs up, :Y:

 

[Tathradj]

Shorter than yours and Thank You.

 

[Ridge Runner]

Shorter than yours

Yes it was, But the OP never stated for what type of machine the small coil was for, So it was best to cover all bases seeing as mind reading is not my Forte'

 

[mxt sniper]

I use a digital reloaders grain scale works great on tiny nuggets. You can get a digital small pocket scale on ebay that reads in grains as well as oz and grams.

 

[Goldfreak]

Thanks for the answers, had no idea about "saturation" before. Previously thought it was down to physical coil size.

 

[Ridge Runner]

Thanks for the answers, had no idea about "saturation" before. Previously thought it was down to physical coil size.

Yeah some of the guys here are really good with their PI machines and some of the tiny Gold they find with them defy the laws of physics when you see the specks of Gold they find compared to the coils they use.