I've configured the PSU I got a while back. This is needed for the 5.8GHz video transmitter from Range Video.
It was pretty straightforward to assemble. I put a JST connector on the input and output, desoldered the 12V pad, and soldered the 3.3V pad. I wrapped the whole thing in a 3/4'' shrinktube, but a 1/2'' would have been better.
I'm not sure what the signal line is for.