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@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user