White noise generator LM324
"White noise" is a kind of noise for which the frequency ranges from low to high values. The "shower-like" noise you can hear when you hit an empty spot on the dial of an FM radio with FM mute off is an example.
It is a useless noise to most electronic engineers. But to the people playing various electronic musical instruments, it is essential as a sound source. You can generate it by applying a reverse voltage across the base and emitter of Q1. The schematic shows you that U1:A is used as an oscillator.