I recall an old article stating to place the camera facing North and if placed East / West the sunlight would trigger the camera . I have had good results by doing this but also the shadows trigger the camera and I get several pictures of nothing .
I remember that movie . Collars would be paired with another prisoner but they didn't know who they were paired with . If the two paired collars got too far apart , they would explode . Sounded like the ideal baby sitter for prisoners !