Free Modular

Mixer Assembly Instructions

See general assembly instructions

Components

See general components notes for more info about acquiring parts.

Interactive BOM

Reference Part Value Source Comment
R1-R9 Resistor 100kΩ   Any value is fine for these, as long as they are all the same, and are significantly higher than the output impedance of the sources you are mixing.
R10 Resistor 1kΩ   Determines output impedance. Any value is fine.
R11 Resistor 4.7kΩ   Determines LED brightness. You may want to use a different value if you have different LEDs. A lower value means less resistance and brighter LEDs.
C1,C2 Capacitor 100nF   [Optional] Power supply noise filtering capacitor
C3,C4 Capacitor 33pF   [Optional] Amp stabilization. Anything in the 100pF-33pF range is probably fine.
C5,C6 Capacitor 10uF   [Optional] Power supply noise filtering capacitor
RV1-RV4 Potentiometer A100kΩ Thonk Logarithmic is best if you primarily want to mix audio. Any value should work for these as long as they are significantly higher than the output impedance of the sources you are mixing.
SW1-SW5 Switch TAIWAY 200CWMSP1T3B4M2 Thonk, Love My Switches SPDT ON-ON
J1-J6 Jack Socket PJ301M-12 Thonk  
J7 Power header IDC male 2x5    
J8, J9 Jumper headers     [Optional] Chain multiple modules together by connecting OUT to IN.
D1 LED 3mm   Indicates output level. Optionally, you could use a bidirectional/bipolar LED here. Using a normal LED as shown in the design, with anode on top, will only illuminate when the mixer is outputting a positive voltage.
U1 Op-amp TL072