Tonewheel

A tonewheel is like a tiny little disc that has bumps on it, kind of like braille. When you press a key on a musical instrument called an organ, it makes the tonewheel spin really fast. As it spins, there's a special thing called a pickup that senses the bumps on the tonewheel and turns them into sound. So when you press different keys on the organ, it makes different tonewheels spin and creates different sounds. It's kind of like a fancy music box with lots of different little spinning discs inside!