Polarized coil?????

ian field

Joined Oct 27, 2012
6,539
Good reasoning. Maybe because it is radial and the leads are under the coil it would be harder to mount if the same size??
That's probably the right answer - but there is such thing as a polarized inductor.

At one time they were common on CRT TVs. A linearity coil in series with the horizontal scan coils had a magnet associated with it, on VGA monitors the magnet was more usually permanently glued to the inductor core, on TVs with large wide angle deflection CRTs the magnet was usually adjustable by rotating with a trimming tool.
 

SLK001

Joined Nov 29, 2011
1,543
It sometimes is important that the resulting magnetic field is oriented in the right place and polarization. Mount it one way and the polarization is right hand - mount it the other way and the polarization is left hand.
 

GopherT

Joined Nov 23, 2012
8,012
It sometimes is important that the resulting magnetic field is oriented in the right place and polarization. Mount it one way and the polarization is right hand - mount it the other way and the polarization is left hand.
That is crap. That is like saying if I put a nut on one end of a threaded rod I turn to the right, and if I flip the threaded rod I would have to put a nut on it by turning to the left. In reality, a common threaded rod is always righty tighty and lefty loosely.
 

SLK001

Joined Nov 29, 2011
1,543
That is crap. That is like saying if I put a nut on one end of a threaded rod I turn to the right, and if I flip the threaded rod I would have to put a nut on it by turning to the left. In reality, a common threaded rod is always righty tighty and lefty loosely.
Sorry, not crap. The magnetic field is determined by the direction of the current thru the coil. Mount it one way and the current goes up the coil. Mount it the other way and the current goes down the coil. And we're talking coils here, not threaded rods - your analogy could not be more wrong.
 

cmartinez

Joined Jan 17, 2007
6,674
Sorry, not crap. The magnetic field is determined by the direction of the current thru the coil. Mount it one way and the current goes up the coil. Mount it the other way and the current goes down the coil. And we're talking coils here, not threaded rods - your analogy could not be more wrong.
The part mentioned is not an electromagnet, but rather an inductor, so it doesn't matter which way the current flows.
 

SLK001

Joined Nov 29, 2011
1,543
The part mentioned is not an electromagnet, but rather an inductor, so it doesn't matter which way the current flows.
What do you think an electromagent is? In some applications, it may not matter which direction the current flows, but this isn't always the case.
 

wayneh

Joined Sep 9, 2010
16,162
An inductor coil can produce a field that interacts with nearby components. So, the polarity of the field can matter. It would make sense to mark it for that reason. I have no idea about the part in question.

A right hand helix is still right hand if you turn it around, but reversing the leads changes the direction of current flow and thus field polarity.
 

cmartinez

Joined Jan 17, 2007
6,674
What do you think an electromagent is? In some applications, it may not matter which direction the current flows, but this isn't always the case.
I would sincerely like to see an application in a PCB where the orientation of the inductor's field is considered important. Other than for its being used as an electromagnet, of course.
 

Thread Starter

spinnaker

Joined Oct 29, 2009
7,837
I would sincerely like to see an application in a PCB where the orientation of the inductor's field is considered important. Other than for its being used as an electromagnet, of course.
I would think boards where there are other conductors in close proximity,

You should have seen the AFC board for the seeker for the Harpoon missile back in the early 80's. All discrete components. The board was about 15cm wide, maybe 30cm length in a half circle. It was so tightly packed with components that you could not see the board. There must have been thousands of components. The rumor is the engineer that designed the board went insane shortly after. I have no idea how they were even able to build such a board let alone repair it.

I could see magnetic fields being an issue on a board like that.
 

SLK001

Joined Nov 29, 2011
1,543
I would sincerely like to see an application in a PCB where the orientation of the inductor's field is considered important. Other than for its being used as an electromagnet, of course.
Build a passive filter. Cross-coupling can kill a filter's response.
 
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