I built this air raid siren ten years ago. Looking at the old video, I realized I could edit that much better now. This version is only half as long without skipping much!
Article about the siren build: http://woodgears.ca/siren
2012 building the siren: https://youtu.be/XAfvOjdZpkg
2012 testing the siren: https://youtu.be/2Tr6hCZAVhI