Re: gEDA-user: Parts Manager Working Document

[Gabriel Paubert <paubert@xxxxxxx>]

On Mon, Jan 18, 2010 at 02:23:16PM +0000, Peter Clifton wrote:
> On Mon, 2010-01-18 at 14:45 +0100, Gabriel Paubert wrote:
> > Consider that some inductances that I use are not symmetric. While
> > I don't know of any asymmetric resistors (but maybe they exist), 
> > some microwave broadband inductors are asymmetric (you can't swap 
> > pins 1 and 2, as for polarized capacitors):
> > 
> > http://www.piconics.com/Conicals.html
> 
> I've never seen that kind of thing before (although I don't work in RF).

That's always the case in electronics given the variety of components
that are available.

> 
> For switching power supplies etc.. the physical positioning of coils can
> (sometimes) matter. Assume that given a applied current, the inductor
> produces a magnetic field pattern which isn't symmetric about the axis
> you can swap the component around. This could affect interference in the
> circuitry if you swapped the component around.

For all other inductors I've seen, it's only a matter of turning around 
the inductor when assembling the board. More complex inductive components 
like transformers are another matter of course, but I restricted myself
to two terminal devices.

In practice most inductors have an axis of symmetry and a radiation
pattern so symmetric that the orientation does not matter; conical 
inductors are really different in this respect. On the other hand what 
I have seen with axial inductors is putting them at right angle to 
minimize coupling, and spacing them apart as much as possible.  

> Which terminal of the coil is wound innermost could affect EMC /
> electrostatic coupling. (Probably a more important effect than the
> previous one?)

Probably, but once again, it's a matter of turning the inductor around 
at assembly time. 

	Best regards,
	Gabriel


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user