LED Christmas lights from Philips

Filed under:

  • Price: $12 at discount retailers
  • Recommended: not recommended
  • Also available: multicolor sets, sets with diffusers

Philips is a major figure in the lighting industry, so I had high expectations when I picked up two sets of their Christmas lights to review. Let me get right to the point of this review–I don’t recommend this product. Read on to discover why not.

lovely packaging

The packaging certainly looks nice.

Immediately from the information on the package you can make some intelligent guesses about how this system is electrically connected. 60 LEDs, 115VAC, and 40 mA seems to add up to two series strings of LEDs. In our previous article about driving LEDs from AC, we discussed the idea that rectifying the AC would double the effective brightness.

Imagine my disappointment in discovering that this set was so cheaply constructed as to not bother with the rectifier. As a quick review–diodes conduct current in one direction only. Alternating current reverses directions 60 times a second in the US. Rectifiers arrange the current into a one-directional flow.

Update for 2007: the new models of this product appear to have corrected this deficiency. (I wonder if they read my review?) I have not had time to verify it on my bench, but there appears now to be a rectifier included, which overcomes one of my biggest complaints about the set. Stay tuned for further updates.

But the approach this set takes is to use two strings of 30 series LEDs connected in opposite polarity across the AC source, so that only 30 of the 60 LEDs are lit at any given time. There’s a certain elegance to the minimalism of that, but it produces a perceptible flicker in the lights.

the LED advantage

The advantages of LEDs.

Perhaps I’m getting ahead of myself in this review. Let’s take a step back and look at the product’s basic features. This is a string of LED holiday lights. The package proclaims the “LED advantage”

  • Advanced LED technology
  • Bulbs are fade, chip, peel, and break resistant
  • Cool to the touch when lit
  • Ultra low power usage (4.8 Watts)
  • Up to 76% power savings compared to super bright mini sets
  • 25,000 hour average bulb life
  • Connects end-to-end
  • Bulb locking feature

It’s hard to know precisely what they are getting at with the claim “advanced” LED technology. The two sets I reviewed used 5mm indicator LEDs. The package was such that the LEDs have a fairly narrow view angle, so when viewed off-axis they are substantially less bright comared to on-axis. Some variations are available where plastic diffusers in holiday shapes (snowflakes, icicles, and amusingly, C9 bulbs) are fitted to the LEDs. These versions would show less variation in brightness with a changing view angle.

plain 5mm LEDs

The narrow view angle leads to a lot of variation in brightness.

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