26 July - LED torches

If you're in Australia or NZ, you would have seen them all over electronics magazines and stores; high brightness LED torches. Silicon chip Magazine has featured many articles, including a torch, linear power supply, inverter, switch mode power supply with dimmer, bike headlights, LED array camping/caravan/low power lighting and so many more. most of these design utilized a Luxeon 1w LED. I have been told these have amazing light output (I really have to organize evaluation samples :), but one niggle I would have is the colour of this amazingly bright device, actually rated as a class 2 laser device because of its output power. I have bought several ultra-mega-super-dooper-awesome-massive light output 5mm LED's and they are also impressive, but not the colour.

The LED's typically have a "cool white light" - I would describe this as more of a light blue. it is a "cold" light, and although it is great for reading without eyestrain as I tried it for an hour at night, reading my favorite magazine, guess which one :), but most of the time the light colour is unpleasant, even annoying at times. especially when shining at black surfaces, the light is "soaked up" by the colour. Incandescent lamps don't really have this problem, so is there an LED that mimics a lamp?

There is also another explanation for this, what I like to call "the tube effect". it's pretty simple. in the 1950's, Valves or "tubes" were prominent, basically a glass envelope with a vacuum of air in it and the required heaters and bits. these were replaced in the 1960's with transistors, a new switching device made on silicon. They were revolutionary; but people had to get used to them; they didn't sound the same as the old tubes. valves sounded "warmer", many people tell me, and people debate whether it is distortion or harmonics or indeed a sixth sense. anyway, valves were replaced and people had to get used to the transistors.

only lately, LCD/TFT/Plasma/OLED displays have been replacing the CRT (Cathode Ray Tube), or "tube". these are also glass envelopes with a vacuum, and when LCD's came around people had to get used to the sharp, bright, flat display that didn't have the "natural" feathering of a CRT. this also made slight problems with "native resolutions" and the like, but of course the advantages by far outweigh the disadvantages.

I think incandescent lamps are on the same path of these other two tubes. Headlamps in up-market cars are already being replaced by HID lamps, and the LED is replacing the good 'ol torch lamp. Eventually I think LED's will reign over lamps, but we will, again, have to get used to a slightly different output to what we are used to.

Addition: At the theatre I work at, we have put our old CID follow spotlights on death row - they are not making the CID "arc lamps" anymore, after 16 years. I guess we will just have to upgrade to some flashy new HID ones, but just think - a good ten thousand dollars of lighting rendered useless!

"Plug in" to that for some good thinking!
Callum [agent-c]

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