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Double D coil field

L

LabradorBob

Well-known member
Staff member
A new drawing showing the outside coil field,and explaining why the diagram ray-mo found looked as such.
The eddy currents actually keep getting larger till they get fairly close together under the coil.
Any metallic object the field hits,creates an electrical current in the object,cutting the eddy current short, and bounces off,
it creates a different kind of current,that goes right through the eddy currents,back to the reciever side of the coil.
This is in the center of the coil where the two D's overlap!
The drawing just shows the current in the center of the coil,but it goes all along the outside edge.
Thanks,
Harold Reese
 
hey thanks for that,do they make a mono coil for the etrac?or how about a coil that is say powered by batteries that would magnify the signal being sent into the ground?what do you think?
 
silvereagle said:
hey thanks for that,do they make a mono coil for the etrac?or how about a coil that is say powered by batteries that would magnify the signal being sent into the ground?what do you think?
Click to expand...

The signal is already as powerful as the detector can handle. More power would only result in more feedback from the soil.
 
They do make 1 either mono or concentric coil for the e trac.
I just dont remember what it is right now!
Harold
 
Just for thought:
The field from the coil,reaches from the coil,to infinity!
Depth,is limited to a certain distance from the coil,the field gets weaker the further it gets from the coil!
SO,It is my thought that a bigger coil,Wider,puts out a bigger field,but does the field get any stronger?
will it reach farther from the coil?or does it dissipate at the same distance from the coil?
I'm thinking,this is where different types of coils,being made differently,maybe go a little deeper than others.
Heavier windings?
What are some of your thoughts on this?
LabradorBob
 
(Just for thought:
The field from the coil,reaches from the coil,to infinity!
Depth,is limited to a certain distance from the coil,the field gets weaker the further it gets from the coil!
SO,It is my thought that a bigger coil,Wider,puts out a bigger field,but does the field get any stronger?
will it reach farther from the coil?or does it dissipate at the same distance from the coil?
I'm thinking,this is where different types of coils,being made differently,maybe go a little deeper than others.
Heavier windings?
What are some of your thoughts on this?
LabradorBob)

This is a question not knowledge on my part, I may get ridiculed for this thinking but: Kind of along the same lines of thinking about Dbl D depth, I have wondered how much depth difference there is between a 5" coil and say, a 12" coil both being Double D variety. On the theory, that the Dbl Ds put down a narrow long (approx. the dia. of the coil) field . Compared to the mono ( or NON Dbl D) coils that put down a cone shaped field, with the depth of the cone field being relative to the dia. of the coil. Theoretically with the mono coil, the larger the coil, the longer the cone field would be, and, therefore the larger coil would go deeper. But the Dbl D with the narrow long field, going "straight" down. Wouldn't the field, of all sizes of these Dbl Ds, theoretically go more or less the same depth, with the major difference being the length of the field, which actually would just allow more coverage per swing of the coil and approx. same depth.with the larger Dbl D coils?? I have recovered an Indian penny in the 8"-9" range, (near the length of the SunRay probe), and was using a 5" SunRay coil. I have been told "No way, not with a 5" coil", but my hunting buddy watched me dig it up.
 
C&RHunter,
This is my understanding,
The strip down the center of the Double D coils,is actually the receiving side of the coil,The transmitting side of the coil is the
outside of the coil as in the drawing.
The field,from the outside of the coil,in my understanding,can only go to the recieving side on the inside of the coil.
and to infinity everywhere else.
So,my thought would be that if a coil is bigger,which would usually mean wider,this would make the field even larger.
and does the bigger coil make the field stronger?or does is lose strength at the same distance as a smaller coil?
Maybe it relates to the distance between the transmitting side,and the recieving side.
I am no expert here,so anyone feel free to jump in.
Harold
 
I have noticed that dd coils will detect targets a good distance to the outside or edge of coil as in surface coins several inches away from coil,Ray.
 
Correct ray,i have too,the eddy currents that come in contact with a coin,disrupt the current,from what i understand
it creates an electrical field in the coin,this field is relevant as to the type of metal,Thus,getting into discrimination! the field from the coin goes right through the field from the transmitting side of the coil,to the receiving side,above and below the coil.
I'm not sure on this,but i was thinking maybe the transmitting side was maybe a negative field,but when it hits a metal object
the field in the object is positive,and drawn back to the receiving side.
Whats your thoughts?
Harold
 
Never gave coils much thought as far as how they work.The 6" of snow on the ground has given me pause for thought though:rant:
 
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