Christmas LED light strings

[JohnR66]

I've been looking for these LED light strings for a couple years to show in
the stores and I never see them. Well, in a Meijers store for another
reason, I swung down the Christmas decoration isle and to my surprise, I saw
LED light sets! There were 70, 25 and icicle sets. I got the 70 light
string. Price was $8.44

My analysis:

These have a green wire with two circuits of 35 LEDs on each. LED is glued
or embedded in little plastic colored flame shaped "bulbs". They are
permanently glued to the sockets as they claim no replacements necessary.

Colors are: yellow, orange, red, green (seems to be the aqua colored LED)
and blue. For every green and blue LED, there are 2x the other colors
(perhaps a voltage drop or cost issue). They seem to be as bright as the
standard miniature light strings but with vibrant colors.

Strobing effect is quite apparent since each LED is on for a half cycle and
probably only near the peak voltage anyway. Power draw is around 2 watts.

 

[Clive Mitchell]

These have a green wire with two circuits of 35 LEDs on each. LED is
glued or embedded in little plastic colored flame shaped "bulbs". They
are permanently glued to the sockets as they claim no replacements
necessary.

Are the LEDs in series across the mains like the foreverbrite lights?

Here in the UK our LED strings tend to be run from the industry standard
24VAC transformers for outdoor lighting. There's an inline rectifier
and the LEDs are wired in strings of 7 or 8 LEDs with a resistor (if
you're lucky!). The Gallium Arsenide versions use strings of 10 LEDs and
a resistor.

The flicker is there but not noticeable at 100Hz. (50Hz supply)

The quality is getting higher.

Colors are: yellow, orange, red, green (seems to be the aqua colored
LED) and blue. For every green and blue LED, there are 2x the other
colors (perhaps a voltage drop or cost issue). They seem to be as
bright as the standard miniature light strings but with vibrant colors.

The use of a lower number of blues and greens is probably a cost and
reliability issue. The Gallium Nitride blues and greens are much less
reliable in low cost consumer goods. The real test is how long the LED
strings last. Leave it on permanently as part of your analysis.

Strobing effect is quite apparent since each LED is on for a half cycle
and probably only near the peak voltage anyway. Power draw is around 2
watts.

In the UK a retail chain called Habitat was selling LED lights last year
that used the AC to create a neat effect. Each LED was actually a red
and blue chip in inverse parallel so that the lights lit a different
colour on each half of the sine wave. Looking directly at them they
look purple, but as soon as you eye moves you get a psychedelic red and
blue strobing effect.

 

[JohnR66]

Are the LEDs in series across the mains like the foreverbrite lights?
Yes.

Here in the UK our LED strings tend to be run from the industry standard
24VAC transformers for outdoor lighting. There's an inline rectifier and
the LEDs are wired in strings of 7 or 8 LEDs with a resistor (if you're
lucky!). The Gallium Arsenide versions use strings of 10 LEDs and a
resistor.

The flicker is there but not noticeable at 100Hz. (50Hz supply)

They use a full wave rectifier? The ones here definitely flicker at 60Hz. I
put a diode in series and the front half of the string came on. When I
reversed the diode, the other end only lit.

The quality is getting higher.

The use of a lower number of blues and greens is probably a cost and
reliability issue. The Gallium Nitride blues and greens are much less
reliable in low cost consumer goods. The real test is how long the LED
strings last. Leave it on permanently as part of your analysis.


In the UK a retail chain called Habitat was selling LED lights last year
that used the AC to create a neat effect. Each LED was actually a red and
blue chip in inverse parallel so that the lights lit a different colour on
each half of the sine wave. Looking directly at them they look purple,
but as soon as you eye moves you get a psychedelic red and blue strobing
effect.

That would be a neat effect!