On Mon, 15 Feb 2016 10:44:02 +0000, N_Cook wrote:
On 15/02/2016 05:14, wrote:

I have noticed that about half of the LED Christmas light strings have
a "lump" about 1.5 inches long and 1/2 inch diameter in series with
the lights, which have polarized sockets. I assume that it must
either be a diode or a resistor or perhaps both. What puzzles me is
what limits current and polarizes the AC into pulsating DC in the
light strings that do not have any visible "lump"? Perhaps there are
resistors built into each individual lamp, but the lamps that I have
taken loose have the LED leads going directly out the bottom of the
socket. And, I haven't seen any sign of any resistors built into the
sockets themselves.

Anyone know for sure what's going on???

RFI suppressor ferrite cylinder?
LED xmas lights with their long wires and smps are one of
the best ways of corrupting wifi connections.

I really doubt that cheap communist chinese manufacturing would go to
that expense...