[SOUND AMPLIFICATION] - Built-in sound amplifier chip and volume potentiometer for adjustable sound amplification. ^^ [OSCILLATION SOURCE] - High frequency equal amplitude generated by a common base modulation transformer oscillation circuit. ^^ [HIGH FREQUENCY AMPLIFICATION] - High frequency amplitude further amplified for excellent quality. ^^ [HIGH FREQUENCY MODULATION] - Sound capacitors and bias resistor for sound modulation. ^^ [FILTER NETWORK] - Low pass network to filter out high harmonics and achieve sinusoidal waveform.