Here: on CdS light meters v0.3.pdf you can find the most up-to-date version of my writeup on CdS meters.
This is work in progress, but I wanted to use this excerpt in a web discussion already.
I will update this post as new versions are available. PLEASE don’t link to the file directly. The link will break as soon as I update the file.
April 7th, 2010: initial release
April 10th, 2010: expanded part on mercury battery based meters
April 27th some updates, mostly diagrams, not much new work done