Why do car turn signals click?
When you turn your car left or right you hear the familiar click-click sound from the turn signal. At the same time the arrow on the dashboard flashes to show the signal is working. Even though cars have become much more advanced this sound has stayed the same for many years. But have you ever wondered why? Turn signals first appeared in cars in the late 1930s. In older vehicles the clicking sound came from a thermal flasher. When the driver switched on the turn signal electricity heated a small metal strip. As it bent from the heat it completed an electrical circuit and turned the signal lights on. The metal quickly cooled returned to its original shape and broke the circuit turning the lights off. This heating and cooling cycle repeated over and over making the lights flash. The movement of the metal strip created the well known clicking sound. As technology improved car makers replaced the old thermal system with electromagnetic and later electronic systems controlled by computer chips. These newer systems no longer need moving metal parts to flash the lights. However most modern cars still play the click click sound on purpose. Manufacturers keep it because drivers are used to hearing it and the sound reassures them that the turn signal is working correctly even though it is no longer mechanically necessary.