This is a great circuit to allow the a simple CDS Photocell to switch a larger circuit on and off.  

With v2 I added a larger transistor on the end so that a larger amount of current could be used for the circuit being switched.

 

Find the full rundown and explanation on this Adafruit thread: https://forums.adafruit.com/viewtopic.php?f=19&t=82071

 

Special thanks to the wonderful people and moderators at Adafruit for heping me figure this out.