On Mon, 22 Dec 1997 15:47:42 -0500 Robert Nansel <bnansel@NAUTICOM.NET>
writes:


>I meant the "+" sign to indicate the direction current would flow FROM
>the
>diode when forward biased (instead of the more usual direction of
>current
>flow INTO the diode).
>
>Your way is more logical, though, so here's how the original circuit
>would
>look with the "+" representing the ANODE of the diode:

Very old diodes (usually selenium rectifiers) were marked with a + sign
on the *cathode*.  If the diode is used as a rectifier, a "positive
voltage comes out" of this pin.  The "+" end of the diode was connected
to the rectified positive voltage rail, and the other end to the AC
source.

A selenium rectifier is a big 3-dimensional plate type thing, with
terminals on opposite sides.  It would be hard to print a "diode" sign on
it between the two terminals, but easy to mark one terminal "+".  There
is a convention, but it isn't used much any more, and even then it was
confusing (especially for circuits other than rectifiers).