Also known as digital amplifier Class-D amplifier with small size, high efficiency characteristics. Here are a circuit made easy with 555 Class D amplifier. It is the use of ci
rcuit 555 constitute a controllable multivibrator, an audio signal input to the control terminal to obtain a pulse width modulated signal (as shown), to meet the basic requirements for general listening. By the IC 555 and R1, R2, C1 and other components 100KHz controlled multivibrator 50% duty cycle, control the input audio signal terminal 5 feet, 3 feet will get the pulse width of the input signal amplitude is proportional to the pulse signal by L, C3 to answer the call, push the speaker after filtering.