材料BOM表：

R1 = 10K
R2 = 22K
R3 = 22K
R4 = 100K
R5 = 56K
R6 = 5.6K
R7 = 560R
R8 = 2.2K
R9 = 56K
R10 = 56K
R11 = 1K
R12 = 33K
R13 = 330R
C1 = 100nF-63V
C2 = 10µF-25V
C3 = 470µF-25V
C4 = 47µF-25V
D1 = 5mm. Red LED
Q1 = BC327
B1 = 9V PP3 Battery
SW1 = 2 poles 4 ways rotary switch
IC1 = LM358 Low Power Dual Op-amp
MIC1 = Miniature electret microphone