Here is a mixer that can be assembled with few components and does not need a power supply. It can mix signals from sources of good intensity so that they can be applied to an input of an amplifier or other circuit. The mixer is passive in the sense that it has no amplification steps, which means that the amplifier should be good gain.
In the original design we only give 2 channels, but nothing prevents the circuit from having more channels. Circuit input and output wires should be short and shielded. In figure 1 we have the complete circuit of the mixer.
There is no need to have a board or bridge and instead of the trimpots, common log potentiometers can be used. In figure 2 we have the interconnections of the components.
The jacks must be chosen according to the signal sources and for the output we can use a plug according to the input of the amplifier, through shielded cable.
Material list
P1, P2- 100 k ohms- potentiometers or trimpots
C1, C2-1 uF x 25 V - electrolytic capacitors
C3 - 10 uF x 25 V - electrolytic capacitors
R1. R2- 100 k ohms x 1/8 W - resistors - brown, black, yellow
Miscellaneous: box for mounting, wires, solder, etc.
