On Sun, 26 Dec 2010 08:48:30 -0500, Art Todesco wrote:

The string itself is a rectifier. The current through them will be DC,
no reason to further rectify it.. In the case of a string of xmas
lights they have nearly the full line voltage across them. Works fine.

Jimmie
Yes the string (I assume your are talking about a Christmas string)
is a rectifier, but it is only a 1/2 wave rectifier. Adding a full
wave rectifier, as others (and me too) have done, makes the string
brighter and eliminates much of the annoying blinking. Yes it still
blinks, but full wave rectification makes it a whole lot better.

The manufacturers could put an anti-parallel LED in the same package with the
same effect. The power dissipation is the same (application dependent) so the
package wouldn't need to be changed, just another junction on the same die.