Most logic ICs require fast transitions between levels to function properly, while the switch is being made the IC draws additional current, and if it is kept in this intermediate state failure of the chip is possible.
This app note explains how Shmitt triggers are used in circuits that require slow changing signals to drive logic ICs.
Schmitt triggers should be used anytime you need to translate a sign wave into a square wave…
Or they should be used where a slow or noisy input needs to be sped up or cleaned up as in the switch de-bouncer circuit.
A sign wave, I love those. Isn’t that where the fans in a sports stadium have a bunch of signs, and they wave them around.
Sorry I just had to poke fun of the sign wave vs the sine wave. It has already been one of those mornings for me.
Adam