This is the schematics of a simple 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 BC558.
How ever better the transistor quality better the performance. Resistors R2 and R3 can be used for the level control of input signals.
- All capacitors are of ceramic type.
- Always use a battery two reduce noise .
- Avoid using power transistors as Q1. This is because power transistors have high leakage current and it adds to the noise which is not suitable for our purpose here