Coil Discussion

[daddyflea]

Formula given to me by a very knowledgeable person to predict depth based solely on coil size is this. Length plus Width divided by 2 = depth. This seems to be close but bigger Eliptical DD coils usually don't live up to this such as a 10X6 under the formula should get 8". in reality the width seems to be more of a factor and i would expect that coil to get about 7"

Round DD Coils seem to fair better such as a 8" round will usually get 8" but as you get bigger it drops off quickly.

The Sleepers are the Butterfly coils they seem to get almost the depth the same as the width. Thus a 6" Long and 8" wide usually gets about 8".

Never had too much dealings with concentrics myself but I am curious what as to what opinions everybody else has on this subject.

 

[John-Edmonton]

I prefer concentric coils. They give better accuracy on IDing targets. They seem to get as good and sometimes better depth from my experience as similar sized DD coils. Pinpointing off a concentric coil is very accurate, and......depending on how fast the audio cuts off when pinpointing off the inner toe, gives you an idea on how deep and sometimes what a target isn't. Coins, rings at shallow depths have the audio cut off abruptly. Deeper signals and junk targets tend to not cut off as fast. Concentric coils also give an audio when the target is near but not under the coil, alerting you of a target.

Smaller coils are better for separating targets in trashy areas. Smaller coils allow the user to run a higher sensitivity on a unit. This sometimes compensates some depth, as larger coils, especially in the city often times have to have the sensitivity turned town because of too much EMI , too high mineralization in the soil or just too many targets in the soil.

 

[Southwind]

My experience has been pretty close to what you posted. For example I get roughly 8-9" out of my 6x10 coil. Unlike John I do not like a concentric coil. Now I will say the right conditions may favor a concentric, but I've had far better luck, in my soil and type of hunting, with a DD. I can't image hunting a tot lot with a concentric unless it was a very small coil and you planned on being there all day.

 

[chuck ky]

coil size or type wouldn't make much difference in a tot lot. most have a lining under the wood chips so the depth you would dig wouldn't be very much and there's not many that would take very long to hunt.

 

[Southwind]

coil size or type wouldn't make much difference in a tot lot.

Not where I'm from. I hunt 7 tot lots every weekend and only one has a lining.

To get close to the iron playground equipment is going to take a small coil IF it is a concentric. A large concentric would not allow you to get close. Using a small coil will take much longer to hunt any area not just a tot lot. Common sense.

 

[Hoser John]

The maufacturer is the determining factor as a rule of thumb. DD deeper but concentric more sensitive. I've seen NEL coils change minelab units to much better units and visa versa. Coiltec is yet another innovator of some amazing coils. John