Why does a coil of wire appear as a larger-than-life image?

[hard2find]

Why does a coil of wire appear as a larger-than-life image?

Has anyone experienced detecting a little coil that appeared to be much larger?

Also, pc boards have the same effect.

I'm new to this interest.

 

[PAshooter]

Probably has to do with the magnetic field of a coil, like in an electric motor the coil winding is used to genereate more field...? I'm reaching here, really have no idea

 

[hard2find]

Has anyone else experienced this effect on their detector? Maybe, try it on yours and see what you get, eh? Thank you for reading.

 

[hsjrev]

Yup. I can pass the detector over a straight piece of barbed wire with iron disc'ed out and it won't respond at all. Coil that same wire a couple of wraps around a wooden post and it will set the detector off like crazy from a foot away.

 

[homefires]

The open ended coil of wire becomes a tuned circuit. This coil is more effective collecting the RF and Presents more reflected signal to your coil!

 

[hard2find]

Why open-ended?
If the wire is looped then the ends soldered, will it behave differently?
Thank you for reading.

 

[hard2find]

Thank you for doing this.

 

[silversmith]

A closed loop generates Eddy currents when excited by an external ac source. This a very complicated subject requiring an Electrical Engineer. I'm just a dumb radio repairman. Good luck , Ron.

 

[homefires]

[size=medium]Open ended the induced current has no place to go and when the EMF inducing the current goes away, The field set up in the coil collapses inducing yet another field! Ha! How about that? If the coil is closed loop, the current generated in the coil will cancel it's self! This stops the coil from generating the secondary field or Ringing!!! Now that I made that clear as mud, you can look up the term INDUCTANCE


Man, I'm glad I don't deal with that stuff any more![/size]



http://en.wikipedia.org/wiki/Inductance

 

[hard2find]

Thank you very much for your interest and wisdom.
I followed your link and read about inductance. Seems that a toroid(?) would really have a big field, right?

 

[homefires]

[size=medium]Toroid makes better use of the EMF. Sort of concentrates it![/size]

 

[hard2find]

So, maybe a coil of wire can be detected when it is behind other metals, brass/copper?
Does anyone have field experience with this?
Seems that this could occur often.

Thank you for reading.