ELI5: low frequency oscillator

A low frequency oscillator is an invisible, slow-moving rhythm machine that automatically changes something else back and forth over time.

To understand how it works, imagine you are on a playground swing. You are moving back and forth, but you are moving slowly—not fast like a buzzing bee, but slow enough that someone could easily count your swings. In science, anything that moves back and forth at a slow, steady pace has a low frequency oscillation.

Instead of making a sound you can hear on its own, this slow rhythm is used to control other things in everyday life. Here are a few simple examples of how you experience this rhythm around you:

• Blinking holiday lights: The lights on a Christmas tree that slowly fade from bright to dark and back again are controlled by this kind of slow rhythm.
• A car's turn signal: When you sit in a car and hear the slow click-clack, click-clack that makes the blinker light flash, a slow timer is turning the light on and off at a steady pace.
• A swaying fan: An electric fan that slowly turns left, then right, then left again to blow air around the whole room is following this back-and-forth pattern.
• Wobbly musical sounds: If you hear a police siren go slowly wee-woo-wee-woo, or a space sound in a movie that goes wub-wub-wub, an artist used a slow rhythm to gently push the sound's volume or pitch up and down.