Well, Bill, I have posted a picture and a diagram here before. I tried and cannot find the picture I posted, but it was the one used in the book and I have "retired" them all since the book's completion. I can repeat the diagram here in text.

Constant voltage > Light > shutter > Monochromator > step wedge.

The input to the electronic shutter is a precise timer. The whole optical path is on a heavy metal plate to keep it in alignment. It is nothing fancy and could be cobbled together by anyone. A prism or diffraction grating could work. It is all straight line from one end to the other, and about the length of a counter top (~24") and about 10" wide.