matrix for working out coils

Hi whats the matrix for working out area on coils ?, i remember reading something about how with an elliptical you x the length x width then halfed it and that is the size that matches in a round coil,,?? on another post here i read a ?? size coil = 122 inches in area ???? wtf how is that worked out

spider

I think this is what you want

http://www.captain.at/electronics/coils/

http://www.66pacific.com/calculators/coil_calc.aspx

Shane

Hi Spidertice,
What would you do once you have the area of the coil, this would not help in comparing an eliptical coil with any other coil, usually the widest part of the coil will give you an idea of its depth comparison to another coil of similar size, the length of the coil has the advantage of coverage per sweep(hard to miss whilst patchfinding) and the ends are smaller to help with pinpointing. If you wanted to make one just measure around the circumference and divide by phi(3.1416) and you have the dia. and make a coil to that dia. , mind you its a lot more complicated than that. I'm sorry but i fail to see why you need to know the areas matrix????
Regards Ron
PS: if you want any information fire away.

thanks fullas
I was reading another post ( cant find it now) where it was said that the area covered by a 14x9 was 99 inches ?? and the area cover by a 11'' round was 95inches ? and i was wondering how this conclusion was came too,, i would nt have a clue how many wraps there are on my coils nor do i really care, but i thought there must be a simple way to work out your coil = ground coverage,, so you dont double up on coils,, the idea that eg,, a 12 '' coil only goes 12'' down doesnt sit with me

spider

Hi Spidertice,
Whack a coil on and tune then wave a beer can in front of the coil, compare your 12" to say an 18" or whatever and you will see that there is a max. your coil will go down, from memory a 12" will get about 950mm and the other 12-1400mm, but the trick is to try a 1gr nuggy and note the difference maybe then you wont bother using your weenie anymore, only to pick up the small ones left in an area!!
Regards Ron

Spider, Ron is right as an elliptical coil is only a good as its width. Its total area means very little. Even a round 12" will go a bit deeper on small gold than an elliptical 12"x24" BUT the overlapping on that round 12" MONO coil to get this advantage is not worth it with about a small 3" hot spot in the center. Meaning a person has to overlap a round 12" MONO coil 4 times being every 3" that it would take forever to cover ground to get that depth advantage over the elliptical 12"x24" so it is not worth it as I said. (The same comparison could be done between a round 11" and 11"x17" also.)

Ron, I DO understand this part>> Whack a coil on and tune then wave a beer can in front of the coil, compare your 12" to say an 18" or whatever and you will see that there is a max. your coil will go down, from memory a 12" will get about 950mm(37" deep) and the other(round 18" coil will get about) 12-1400mm(47" to 55" deep),

BUT Ron I do not understand this part??>> but the trick is to try a 1gr nuggy and note the difference maybe then you wont bother using your weenie anymore, only to pick up the small ones left in an area!!
Regards Ron <<Ron, can you please explain this a little more as it is appreciated, and also were you using an SD or GP(X) machine, thanks David!

Hi Beerbeeper,
I used the term 1gr gold nuggy, but in actual fact i was testing at that time with a .22m bullet slug, probably weighs in at a bit more than 1gr but what i was referring to was that a small coil (11")will give a depth reading of whatever but stick on a bigger diameter coil and you will be able to pick up that same target at a much deeper depth, of course with smaller targets they are better picked up with a smaller coil, so by all meens use a small coil but on anything decent please use a larger coil, at least experiment.
The detector should be errelevent but i was using a GP3000 standard.
Regards Ron