Get flash to fully experience Pearltrees
YourITronics has a good article on making a Constant Current Source using a Texas Instruments TPS54232 chip.The TSP 54232 is a flexible little chip but you will need to get out the fine pitch soldering iron tip and cut down on the coffee since it is only available in a surface mount package. There is an interesting DIY thermal via system that is used on the board to allow the non-etched copper of the back of the board to be used as a heat sink. “The solder drops that you can see on the back of the board are a sort of DIY thermal vias.
History This project is like the one that all of you must have done in electronics. I took the idea from Circuit Cellar.