On Dec 27, 12:54*am, "Michael A. Terrell"
wrote:
" wrote:

I recently was given two strings of LED blue/white Christmas lights.
The bulbes are in series, with 35 lights in each string. *There are
also a couple of lumps in the series lines. *They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. * My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. *I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. *Has anyone
done any experimenting like this?

* *Leave it alone. The forward voltage drop on white or blue LEDs is
higher than red or green, so that's why they chose *35 LEDs per string.
If you get too close to the actual line voltage and use lower
resistance, any spike will cause a high current surge through the
string. *If you aren't capable and willing to design and build a
constant current boost supply, you are wasting your time.

--
You can't have a sense of humor, if you have no sense.

Good point about surge limiting, altho I am not sure if LEDs are any
more susceptible than tungsten filament lamps.