Horror movie sound effects
The sound that this circuit produces will remind you of the scary music you hear in horror movies.
After wiring the project, use your special light shield and your hand to change the amount of light that falls on the CdS cell.
The music changes in pitch. The pitch of a sound is determined by the frequency of the sound wave-the number of cycles of electromagnetic energy per second.
The amount of light on the CdS cell determines the resistance value of the cell. More resistance from the cell slows down the frequency of the music sound waves.
The basic "music" is produced by the oscillator circuit. When a circuit controls the frequency of an oscillator, we call it FM or frequency modulation. An FM radio signal is something like this, but at much higher frequencies.