Barry Watzman wrote: Blue LEDs are listed as 2 pounds each in my 1994 Maplin catalogue, FWIW (but no sign of white ones then) cheers Jules

I bought a blue LED while I was doing my Ph.D. at Bristol (this would therefore be before 1995). And that was from a hobbyist shop, in 1-off quanities. It wouldn't suprise me that they were around a couple of years before I got mine. -tony

On Thu, 9 Feb 2006, Barry Watzman wrote: LEDTRONICS INCORPORATED * FOR IMMEDIATE RELEASE * 9005 Pacific Coast Highway Torrance, CA 90505 (213) 549-9995 fax (213)549-4820 MARCH 8, 1991 FULL SPECTRUM RGB LED PRODUCES A RAINBOW OF COLORS TORRANCE, CALIFORNIA -- Today, the industry's first integrated red, green, blue (RGB) LED is available for the wide range of applications anticipated since last years introduction of the blueLED. Designated the L300RGB series, this discrete is packaged in a clear or diffused 0.300" ( 8mm ) case. Incorporating state of the art chip mounting technology that dissipates heat in closely spaced chip arrays, this discrete utilizes high efficiency red chips ( 635nm), high efficiency green chips ( 565nm), and 470nm blue chips. Direct access to the RGB chips and a common cathode provide a virtual cornucopia of color to the applications engineer. Within the next six (6) months, this RGB discrete will be available in a T1-3/4 (3mm) package. Design analyses for the T1 (3mm) package are progressing. Additionally, total flexibility in chip selection has been retained. Thus, this device can be manufactured with deep red (660nm), pure green (555nm), and 470nm blue chips. The potential applications for this discrete are as varied as the colors available from it. First, of course, is a the [sic] best rendition of a white color available in the LED market. The L300RGB also serves as the fundamental multicolored pixel for large area full color screens/monitors/displays. Additionally, the L300RGB can be used in full color moving signs/displays, as a light source for a variety of scanners such as used in color copiers and equipment which senses a paper's color differences to detect counterfeit currency, as a spectral analysis reference or source in color scanning and high speed document reading, and color synthesis for photic stimulation/simulation. Data sheets for the L300RGB are available describing the brightness of each chip and related electro-optical characteristics. Necessary bias requirement to operate the L300RGB as a 5 VDC discrete to obtain a white color are also provided. Application notes regarding other colors/characteristics are currently in preperation. Gather up the power supply and decade resistance box -- develop your rainbow of color. Prototype quantities are immediately available. Costs for OEM quantities are expected to be in the $5-$7 range.