/electronics
This is a simple mixer circuit that I used LM-741 operational amplifiers (probably not the best pick) configured as inverting amplifiers to build. The purpose was to be able to mix a CD (stereo) in with a guitar (right channel) and a microphone (left channel). If you are going to build this then I would suggest reading the "absolute maximums" and "application notes" for whatever op amps you decide to try. You should also probably tie a 10k between the output signal and ground for each channel - I dunno why I never put that in. Also, I used two 9V batteries for power. Take a look at the audio mixer circuit diagram below:
