3.3V/5V level shifting (was Re: 4000 Series CMOS Parts?)

On Wed, 9 Nov 2011 23:37:18 -0500 David Riley <fraveydank at gmail.com> wrote: [whilte LEDs] Not exactely. Whilte LEDs are based on blue LEDs and a fluorescent that converts part of this blue light to longer wavelengts. I sugest you go to the site of a major LED manufacturer like Cree or Nichia, donload some data sheets and look at the spectrums. Usualy the spectrum has a peek at around 450 nm, but not that narrow like a blue LED without fluorescent. Often there is a gap at around 500 nm and then a broad "hill" at 550 nm to 600 nm depending on color temperature. So the spectrum is quite smoth. Most whilte LEDs have a Color Rendering Index of 70%..80%, where sun light is 100% and incandescent lamps are close to this. There are high CRI LEDs with a CRI of around 95%. One of those is lightening my living room at this very moment. It needs 14 W and produces as much light as a 60 W incandescent lamp. It has a color temperature of 5000 K, that fits to the 5500 K calibration of computer screens much better then incandescent lamps. (2700 K or 3200 K for halogen) Incandescent replacements based on LEDs are a poor choice. Incandescent lamps work better the hotter they get. So the fixtures for incandescent lamps are made in a way that isolates as much heat as possible. This is absolutely contrary to the needs of LEDs. LEDs need to stay cool. They need a loot of cooling to keep the junction temperature in a reasonible range. They decay fast when hot and the efficieny drops. Unfortunately real LED lapms, that are constructed according to the needs of LEDs, are rare. Thats why I build LED lamps myself, as I am the geek, that I am. ;-) Ahh, low to mid power, high efficient LEDs can produce about 10 times more light then an incandescent lamp! Though, most high power LEDs with acceptable to good CRI are around factor 4 to 5. That is about the same efficiency as CFLs. There are UV LEDs. But they are not as efficient as blue LEDs and they decay quite fast due to the UV light they produce. Therefore they are not used for white LEDs. -- \end{Jochen} \ref{http://www.unixag-kl.fh-kl.de/~jkunz/}