A cheap audio amplifier

The circuit uses the integrated dual operational amplifier I_M358 as the voltage amplifier. The first stage (1/
21C1) is the front-stage inverting amplifier, which will move weak signals for voltage amplification. The second stage (1/21C1) constitutes a buffer isolation amplifier
, which is characterized by high input impedance and low output impedance, thereby improving the load capacity of the front-stage op amp and effectively blocking the influence of the
subsequent stage load on the front-stage amplifier. Influence. The final stage uses the audio power amplification integrated circuit LM386 (1C2), which
amplifies the signal sent from LM358, and drives the speaker BI to emit sound through the coupling capacitor c5.
    Potentiometer RP1 is a negative feedback resistor. Adjusting the resistance of RP1 can change the voltage amplification
factor of the first stage. Adjusting the resistance of RP2 can change the size of the input signal of IC2 to achieve
the purpose of adjusting the output volume. Resistor R 5 and capacitor C4 are high-frequency correction networks to prevent self-excitation of the amplifier. The output capacitor
C5 not only plays the role of DC isolation, but also affects the frequency response of the low-frequency end.