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Michael A. Terrell Michael A. Terrell is offline
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Default LED Series Christmas Lights


" 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.


--
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