final printed circuit project @ New England Tech

1. 6 Channel Mixer
Jean G. Occeus Jr.
New England Institute of Technology
EET 258

2. Device Description
 This device is a 6 channel mixer designed to combine
three line inputs with three microphone inputs, and
send all the signals to one output.
 A 6 channel mixer is used in audio production to
combine various wave forms (guitar, drums, vocals,
etc.) and create an overall mix of the audio for
recording and/or live performances.

3. 2 Current Models
Mackie DFX6- 6 channel mixer with effects
• +48 v Phantom power for microphone connections
• ¼” inputs and outputs
• Slider knobs and LED monitoring
• On board 32 bit digital effects (Reverb, Flange, etc.)
• High and Low frequency equalization
Soundcraft EPM6 6-Channel Mixer
• 2 Auxiliary buses
• XLR and ¼’ microphone or line connections
• RCA jacks
• 3 band and 2 band equalization
• Led monitoring
• 1 headphone output

4. 6 Channel Mixer 3 Mic Inputs/ 3 Line Inputs
 Block Diagram 6 Volume Controls
3 Microphone Amplifiers
VOL
1 Main Mix Amplifier
MIC IN 1
1 Main Mix Volume Control
VOL
1 Main Output
MIC IN 2
VOL
MIC IN 3
VOL
LINE IN 1
VOL
VOL
LINE IN 2
OUTPUT
VOL
LINE IN 3

5. 6 Channel Mixer
Schematic

6. Block / Schematic
 Reference Section
◦ 6 circles on the block diagram are used to identify the inputs and outputs on the
schematic.
◦ Microphone inputs on the block diagram are associated with a 10 microfarad
capacitor and a 1 kilo-ohm resistor feeding the amplifier section on the
schematic.
◦ #1-#3 triangles on the block diagram are associated with the LM741 microphone
amplifiers on the schematic.
◦ VOL rectangles on the block diagram are associated with the 10 Kilo-ohm
volume control potentiometers on the schematic.
◦ #4 triangle on the block diagram are associated with the Master Mix amplifier on
the schematic.
◦ Dual 9V power supplies are used on the schematic, but are not referred to on the
block diagram.

7. Simulation and Results
4 channel
oscilloscope
Channel A
Sine Wave
Channel B
Triangle Wave

8. Simulation and Results
4 channel
oscilloscope
Channel A
Sine Wave
Channel B
Triangle Wave

9. Simulation and Results
Bode Plotter
Output =
Band-pass Waveform
Frequency Cutoff=
25.009 Hz

10. Simulation and Results
Bode Plotter
Output=
Band-pass Waveform
Frequency cutoff @
141.8 Khz

11. Simulation and Results
Oscilloscope
Sine wave showing
volume control and
clipping

12. Simulation and Results
Oscilloscope mixer
output
Sine Wave showing
peak to peak
voltages

13. Simulation and Results
Multisim Simulation
Schematic
1 Function Generator
producing a 1 Khz
Sine wave
1 Function Generator
producing a 1Khz
Triangle wave
1 Oscilloscope
monitoring the
amplifier outputs
1 Oscilloscope
monitoring the Master
Mix amplifier output.

14. PCB Layout
 The 6 channel
mixing board was
laid out to make the
inputs and outputs
accessible.
 The design is
intended to
resemble the layout
of the schematic.

15. PCB Layout
 3D model of the
overall layout of the
6 channel mixing
board.

16. Manufactured Printed Circuit Board

17. Completed Printed Circuit Board

18. Printed Circuit
Board Pricing
Board Price:
•1=$
•1000=$

19. Pricing of Mixer
1. 1 mixer would cost
$325.00 for one day
shipping.
2. 1000 mixers would cost
$4.61 each for one day
shipping.

20. 6 Channel Mixer Video
• 1 Microphone
connected to input
channel 1.
• 1 radio connected to
input channel 2.
• The out of the mixer is
connected to the
LM386 amplifier
feeding an 8 ohm
speaker.
• Voice and Music are
mixed together at the
output.

21. Retrospective
The 6 channel mixing board was designed to mix 6
inputs through one output using an operational amplifier. The
problem with this design is its inability to adjust the volume of
the mixer’s output.
Future modification to the printed circuit board would
including volume control for the output, and a LED display for
visual monitoring of the overall signal.

22. Closing Slide
In closing, I would like to
thank New England Institute
of Technology for educating
me, and helping me see the
importance of engineering in
the everyday world.
A special thanks to
professor Recorvitz for his
patience and dedication to the
electronics engineering
program here at NEIT.
Albert Einstein’s quote:
“Education is what remains
after one has forgotten
everything he has learned in
school.”