This circuit was designed and built to replace the linear current source I repviously designed. The linear design heated up quite a bit because of the power loss from the regulator and required a long warm-up time before the current stabalized. The new design uses a buck converter to reduce power loss and therefore reduce the heat produced. Of course, any design with a switching supply will have some switching noise, but this can be reduced by using a large output capacitor.
Note: I did not layout a PCB for this design; instead it was constructed on a proto-board.