Low-power light-bulbs

I’ve been experimenting with different low-power light options around the house.  CFLs, dimmable CFLs, and most recently some Philips LED bulbs.

Since so many of my switches have been replaced with X-10 or Insteon dimmer switches, I need bulbs that can support dimming, or at least not be damaged by it.  The dream bulb would be something with the same colour-rendering and dimming behaviour as an incandescent, but still low-power.

No low-power bulb has knocked my socks off yet, but the weird-looking one pictured to the right has come the closest.

So far, I’ve been disappointed in the following ways:

  • Regular CFLs
    • Not dimmable.
    • Long warm-up time.
    • Start-up is hard on them, frequent on/off cycles can shorten the bulb life.
  • Dimmable CFLs
    • They dim, but they don’t dim very much before shutting off entirely.
    • The colour doesn’t get warmer (redder) as they dim.  They stay the same white colour.   Doesn’t give you the same moody ambience as a dimmed incandescent.  Dimmed CFLs seem harsh by comparison.
    • Still have the long warm-up time and suffer under frequent on/off cycles.
  • Phosphor-coated LEDs
    • These use a powerful blue LED, coated with phosphors that absorb the blue light, and re-emit it at other wavelengths, giving a better approximation of true white light.  They have pretty good colour-rendering.  Most white LEDs are made this way.
    • There’s often a frosted plastic diffuser around the outside which is supposed to spread the light more evenly, but their effectiveness is limited.  LED bulbs tend to work best as spot-lights.
    • No warm-up time.
    • I’ve found white LED bulbs made this way, even when labelled as “soft white”, still seem harsh and cold to me.  The “soft white” CFLs usually look better.
    • Some models are dimmable, and they can go quite dim before shutting down.
    • When dimmed, the light doesn’t redden.
  • RGB LEDs
    • These use three separate red, green and blue LEDs combined to make something that the human eye interprets as white (metamerism).  But it isn’t white.  These would have a very poor colour-rendering index.  If you used them, for example, to illuminate a painting, it would probably distort the colours badly compared to a true incandescent white-light source.  A pigment in the painting that reflects a particular wavelength of light can’t reflect a wavelength that isn’t actually there.
    • RGB LEDs can be programmed to produce any colour.  In theory, they could emulate the reddening effect of dimming.
    • No warm-up time.
    • These are actually rare.  I haven’t seen any offered as replacements for household light-bulbs.

I’ve got a bunch of CFLs installed now.  The dimmable CFLs are disappointing when dimmed, so in places where I actually care about dimming, I’m still just using incandescents.

Philips AmbientLED BR30

Recently, I’ve been trying some LED bulbs from Philips.

The first was a 12W (65W-equivalent) BR30 flood light.  Supposedly “soft white”, but I found the light was harsh compared to a 65W incandescent bulb, and even compared to a “soft white” CFL.  It dimmed much better than my dimmable CFLs, but still wouldn’t go as dim as an incandescent would.  Like the CFLs, the colour didn’t redden when dimmed like an incandescent would, so it doesn’t give that nice ambience.

Philips AmbientLED "A"

The other LED bulb I’ve tried is another in the AmbientLED line.  This one is shaped to replace a standard 60W “A”-shape bulb.  It’s a weird looking beast, but it’s the best low-power bulb I’ve tried yet.  The weirdness of it comes from its unusual “remote phosphor” technology.  In most white LEDs, the phosphor is a coating applied directly to each LED.  LEDs tend to radiate out in one direction, so these bulbs have very directional light.  Diffusers can only do so much.  But in this bulb, the LEDs are just blue, and the phosphors are embedded in the orange plastic diffuser pieces around the outside of the bulb.  This has the effect of making the light much more omnidirectional.

I haven’t yet had a chance to try the dimming behaviour, but I expect it would be similar to the other dimmable LED bulb from Philips.

EDN News has an interesting tear-down of this bulb, showing the internals.

1 Response to “Low-power light-bulbs”

  • I wished they made high-efficiency bulbs of the very same wattage as incandescent but many times brighter. Forget the dimmer — my eyes are getting dimmer in my old age :)

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