"Sound" existing in this world is created by vibration of objects such as air and water. A site that can interactively know such "sound formation" is "Let's Learn About Waveforms"is. On this site, it ...

A description of a four-phase RC oscillator of a sinusoidal and rectangular shape is given. A triangular-shaped signal is obtained by the counterphase addition of half-waves of sinusoidal signals ...