When I was a little kid, I saw part of a science fiction film on TV that I found pretty unsettling. The main scene I recall is a view from space of the Earth, with an alien saucer-shaped spaceship in the foreground. As the Earth slowly turned in the background, arcs of electricity flared between the ship and the planet. Pretty clearly, the effect was achieved by connecting the ship-model and planet-model to the opposite poles of a battery or generator.
Less certain in my memory is a scene of two people walking nervously down a street, seeing victims of the alien death-ray slumped where they fell. The idea I came away with was that the aliens were using their weapon to just kill random people from space, and would presumably continue until everyone on the planet was dead. Very scary!
My best guess would be that I saw this movie in the late 1970's, or early 1980's at the latest.