I’ve been designing a variable current-regulated supply to drive a string of 7 Luxeon LEDs at up to 350 mA. I’m using the classic 1 watt parts, but this could be adapted for the newer parts easily enough. Since it’s line-powered and I’m designing for a specific number of LEDs (i.e. specific voltage drop), a linear regulator isn’t really that wasteful, so I’m using a LM317 in a constant current configuration which will be adjustable from about 12 mA to 350 mA. I’ll post a schematic once I actually test this out.

And that brings me to the fact that I really should learn to use some schematic capture software at some point. So, I’m playing with the free version of Eagle, and I immediately run into the problem of “What if one of my parts is not in the libraries?”

So, I Google a bit and find myself watching this tutorial video and it makes passing mention of the Texas Instruments TLE2426.

Wow, cool. A virtual ground (i.e. a precision 1/2 Vcc source/sink) for all your single-supply opamp circuits and stuff. Without bothering with a precision voltage divider and opamp voltage follower. Think portable headphone amplifiers and stuff. Unsurprisingly, the author of the tutorial above mentions it in this context on a page about Virtual Ground Circuits.