{"id":828,"date":"2012-11-07T23:20:09","date_gmt":"2012-11-07T22:20:09","guid":{"rendered":"http:\/\/www.sciencetronics.com\/greenphotons\/?p=828"},"modified":"2025-06-16T18:38:19","modified_gmt":"2025-06-16T16:38:19","slug":"the-best-led-bulb","status":"publish","type":"post","link":"https:\/\/www.sciencetronics.com\/greenphotons\/?p=828","title":{"rendered":"The best LED bulb?"},"content":{"rendered":"

At least the best one I have seen so far. After giving a lecture on LEDs yesterday I finally unpacked and tested my latest buy – the clear E27 LED bulb LEDARE<\/em> from IKEA<\/a>.<\/p>\n

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The clear E27 LED bulb LEDARE from IKEA.
(Image linked from IKEA’s homepage.)<\/figcaption><\/figure>\n

The specs of this LED bulb are not overly impressive, with an efficacy of a mere 50 lm\/W it is about as efficient as a compact fluorescent lamp and with its 400 lm it corresponds to a 30 W to 40 W light bulb. Running at 8.1 W this means that it will consume only 20-25% of the electricity of a comparable incandescent bulb. <\/p>\n

But what really amazed me was the high quality of the light. It is a nice warm white, stated as 2700 K on the package, much comparable to the best compact fluorescents I have seen and close to an incandescent – if this is what you are after. Not only is the visual impression of the light very good, also the color rendering is very good. <\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
socket<\/th>\nE27<\/td>\n<\/tr>\n
size<\/th>\n59 mm diameter, 119 mm length<\/td>\n<\/tr>\n
voltage<\/th>\n220 V – 240 V<\/td>\n<\/tr>\n
power<\/th>\n8.1 W<\/td>\n<\/tr>\n
output<\/th>\n400 lm<\/td>\n<\/tr>\n
color temperature<\/th>\n2700 K<\/td>\n<\/tr>\n
CRI<\/th>\n> 85<\/td>\n<\/tr>\n
lifetime<\/th>\n20000 h<\/td>\n<\/tr>\n
on\/off switching<\/th>\n100000<\/td>\n<\/tr>\n
manufactured in<\/th>\nIndia<\/td>\n<\/tr>\n
price<\/th>\nSEK 99 (EUR 12, Nov. 2012)<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

So, how does IKEA accomplish the pleasant spectral composition of the light bulb? I taught my students that the best way to do this is by using the correct blend of phosphors, like in compact fluorescents. But then there was a distinct red appearance when I looked closely at the LED bulb. The LEDs themselves are hidden underneath a light-spreading plastics cone inside the clear glass dome of the bulb – interestingly this cone is screwed to the bulb, not glued as you might expect.<\/p>\n

\"\"<\/a>
The LED light bulb LEDARE from IKEA after removing the glass dome.<\/figcaption><\/figure>\n

However, the glass dome itself is glued to the solid metal lamp socket which serves as heat sink for the internal converter and the LEDs themselves. I was not able to remove it without breaking, but the rest of the bulb remained undamaged. So how does it look under the hood?<\/p>\n

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The LED light bulb LEDARE from IKEA after removing the light-spreading cone.<\/figcaption><\/figure>\n

The solid cast metal socket carries a COB (chip-on-board) unit with 6 LEDs: <\/p>\n