3通道频谱分析仪电路 (3 Channel Spectrum

3通道频谱分析仪电路 (3 Channel Spectrum Analyzer)

This 3 channel 15 LED spectrum analyzer is the perfect addition to any audio amp project. It produces fantastic displays on three LED bars that can be individually adjusted for any particular frequency range. The circuit will take line level output from most any audio source, and operates on 12V DC. This means that it can even be run in a car.

Schematic

Parts:

Part
 Total Qty.
 Description
 Substitutions
 
R1
 1
 100K 1/4W Resistor
 
 
R2
 1
 820K 1/4W Resistor
 
 
R3, R14, R16, R18
 4
 2.2 Meg 1/4W Resistor
 
 
R4, R5, R6
 3
 22K Pot
 
 
R7, R8, R9, R25, R27, R29
 6
 10K 1/4W Resistor
 
 
R10, R11, R12
 3
 680 Ohm 1/4W Resistor
 
 
R13. R15, R17
 3
 580K 1/4W Resistor
 
 
R19, R20, R21
 3
 39K 1/4W Resistor
 
 
R22, R23, R24
 3
 47K 1/4W Resistor
 
 
R26, R28, R30
 3
 33 Ohm 1/4W Resistor
 
 
C1, C5, C6
 3
 0.012uF Polystyrene Capacitor
 
 
C2, C9, C10, C11
 4
 3.3uF Electrolytic Capacitor
 
 
C3, C4
 2
 0.0022uF Polystyrene Capacitor
 
 
C7, C8
 2
 47nF Polystyrene Capacitor
 
 
C12, C13, C14
 3
 0.47uF Electrolytic Capacitor
 
 
C15, C16, C17
 3
 22uF Electrolytic Capacitor
 
 
D1, D2, D3
 3
 1N4002 Silicon Diode
 
 
D4, D5, D6, D8, D8
 5
 Green LED
 
 
D10, D11, D12, D13, D14
 5
 Amber LED
 
 
D16, D17, D18, D19, D20
 5
 Red LED
 
 
U1
 1
 LM3900 Quad Op Amp
 
 
U2, U3, U4
 3
 AN6884 Bar Graph IC
 
 
MISC
 1
 Board, Wires, Sockets For ICs
 
 
Notes:
1. The circuit expects line level inputs. If you connect it to speaker level, you will have to readjust the circuit every time you change the volume.

2. After the circuit is connected, apply power and signal. Now adjust the pots until the corresponding group of LEDs reacts.