The B3603 is an affordable constant current or constant voltage DC to DC converter.
I works great as a bench top power supply and takes 6-40VDC in and delivers 0-36VDC up to 3A. Accuracy is also pretty good.
As a side project a few people have been looking at writing alternative firmware for it. EEVBLOG forum discussion.
Personally I have other plans for these little power supplies and will review my finds very soon. 🙂