Low cost Mic Mixer
This is the schematics of a low cost mic
mixer that can be assembled from the components in your junk box.This
two channel mike mixer is designed for handling high impedance dynamic
microphones.Transistor Q1 can be any general purpose pnp transistor like
BC177 or BC157B. Resistor R5 biases the transistor while R3 and R4
provides channel isolation. How ever better the transistor quality
better the performance. C1 and C2 performs the job of input coupling
and DC isolation while C4 is the output DC decoupling
capacitor.Resistors R1 and R2 can be used for the level control of input
signals.
Circuit Diagram With Parts List. 
Notes
- All capacitors are of ceramic type.
- Always use a battery two reduce noise .
- Avoid using power transistors for Q1. This is because power transistors have high leakage current and it adds to the noise which is not suitable for our purpose here
