Date: Sat, 20 May 2000 20:38:15 +1000 From: "Rowan Crowe (NoSpam)" Newsgroups: aus.electronics, alt.energy.homepower Subject: High brightness white LEDs Hi all, Last night I got a hold of some high brightness white LEDs (thanks Michael) and they're pretty amazing. They are 2000mCd min/4000mCd typical @20mA, 5mm clear lens (20 degree half angle) devices. A couple of interesting observations: 1) They're whiter and brighter (perceivably, anyway) than the Jaycar [Australian retail electronics supplier] white LEDs which are claimed to have a brightness of 6000mCd. 2) They're so efficient that by using my finger as a series resistor, there is still a glow from them. My DMM couldn't measure the current as it was miniscule - below 10 microamps (0.01mA). I set up a simple experiment on the breadboard, with 2 strings of 3 LEDs each, and a 100 ohm series resistor on each string. The light output from the 6 LEDs is enough to dimly light a small room, and very uncomfortable to look at directly. The "spot" output shined onto a wall is roughly equivalent to a small to medium sized torch, but with a current draw of only 40mA at 12V. A 100k resistor in series still produces low level but useable (at close range) light, with a measured current draw of only 60 microamps at 12V! This could be handy as a "finder" light for a switch, or for an LED torch so you can see where before turning it on to full brightness. Only a year or two ago I was excited about buying a 300mCd white unit from Dick Smith. These units blow that out of the water in terms of brightness and whiteness. Things have come a long way and I expect in the future we will see even more advances in this field. One thing I'm curious about - with ultra efficient visible light LEDs now the norm, have IR LEDs also followed the same path? Cheers. -- Note: XXXXXX is actually a valid address, aliased to my REAL one. Remove the '-ns' to reach my real email address directly. Rowan Crowe http://www.rowan.sensation.net.au/ Sensation Internet Services http://www.sensation.net.au/ Melbourne, Australia Phone: +61-3-9388-9260