声级计电路 Sound Level Meter

声级计电路 Sound Level Meter

This nifty sound level meter is a perfect one chip replacement for the standard analog meters. It is completely solid state and will never wear out. The whole circuit is based on the LM3915 audio level IC and uses only a few external components.
Schematic

Original Schematic

Parts
 

Part
 Total Qty.
 Description
 
C1
 1
 2.2uF 25V Electrolytic Capacitor
 
R1
 1
 1K 1/4W Resistor
 
D1
 1
 1N4002 Silicon Diode
 
LED1-LED10
 10
 Standard LED or LED Array
 
U1
 1
 LM3915 Audio Level IC
 
MISC
 1
 Board, Wire, Socket For U1
 

Notes
1. V+ can be anywhere from 3V to 20V.

2. The input is designed for standard audio line voltage (1V P-P) and has a maximum input voltage of 1.3V.

3. Pin 9 can be disconnected from ground to make the circuit use a moving dot display instead of a bar graph display.