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.
- 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