10 LED Sound Level Meter

This is sound level meter for your hand made audio device. This circuit will display like spectrum in Jet Audio software.

Supply voltage can be from 3V to 20V. The input is set for audio line voltage (1V peak to peak) and has a max input voltage of 1.3V. To make the circuit use a moving dot display instead of bar graph display, Pin 9 can be should be disconnected from +V.

Parts List.

C1 C2, C3 R1, R3 R2 R4 R5 D1 Q1 LED1-LED10 U1 MISC

2.2uF 25V Electrolytic Capacitor 0.1uF Ceramic Disc Capacitor 1K 1/4W Resistor 10K 1/4W Resistor 100K 1/4W Resistor 1M 1/4W Resistor 1N4001 Silicon Diode BC 558 PNP Transistor Standard LED or LED Array LM3915 Audio Level IC Board, Wire, Socket For U1