|Siren# 166 on Woodlake south of Strathern, West Hills|
|Sirent# 209 on Tujunga Ave North Hollywood at Fire Station# 60|
If you are old enough, you will easily recall the sirens being tested on the last Friday of each month at 10 AM.
I also recommend visiting the Flickr page dedicated to these air raid sirens and the video below of an air raid siren tested at some guy's house to give you an idea how loud these things were. I also love the part where they show the electric meter spinning ridiculously fast.