i would like to know how to go about buying LEDs.

various types available - diffused / clear

what are Luminous Intensity, peak wavelength, view angle, VF type and what do this tell about LEDs ?

i intend to buy LEDs that will be bright but not super bright .
what to look out for when buying LEDs?

 

Hello,

I think a lot of your questions will be answered by this page:
http://www.gizmology.net/LEDs.htm

It is a link from this page of the EDUCYPEDIA on leds:
http://www.educypedia.be/electronics/composemiconductorsled.htm

Bertus

 

Luminous Intensity, basically how bright the LED, high end LED's produce around 200 lumens, your standard high bright clear 5mm LED's produce less than 2 - 3 lumens typically..

peak wavelength, as the blue light from the die hits the painted phosphorus turns into whitish light, the peak wavelength is simply the strongest wavelength being emitted, typically in the blue range for most LED's but people prefer the warmer color's for outdoor use.

VF, forward voltage, typically around 3 - 3.6v for most white LED's, with the band gap, lower voltages for infrared (2v) / red, higher voltages for green/blue/white..

view angle, without looking I thought this is in which the light is spread, cree's MCE and SSC P7 have really floody angles where as the cree XPE R2 has less of an angle and a little bit more of a tighter beam, depends on the lens the dome use, etc..

diffused means it's colored dome, clear means it's not and produces that light, for example an LED producing white light with a painted/tainted red dome would mean all wavelengths except red is emitted, could be cheaper to produce 50,000 white LED's with different tainted color domes to produce various colors than using different diodes to do the same thing i guess.