Technical specifications

Supply voltage: 12 V
Supply current: 10 mA in stand-by, max. 80 mA
Input voltage: min. 20 mV rms
Indication range: 30 dB
LED currents: 7 mA
Ref. voltage of IC2: 5 V

Schematic diagram

Parts list

R1 - trimmer 100 k mini
R2 - 2,2 k
R3 - 1 M
R4 - 2,7 k
R5 - 6,8 k

C1 - 0,47 uF
C2 - 10 uF
C3 - 47 nF
C4 - 4,7 uF
C5 - 0,1 uF
C6 - 100 uF
C7 - 100 nF

IC1 - LM386
IC2 - LM3915
D1 - 1N4148
D2-D11 - bargraph or LED's

PCB layout