A multi-layered screened PCB can accommodate multiple transistor circuits, including common emitter amplifiers, AC-coupled emitter followers, DC bias, and AC coupling.

Common emitter amplifiers are used to amplify voltage signals. AC-coupled emitter followers are used to isolate DC voltages and prevent signal distortion.

DC bias is used to set the operating point of a transistor. AC coupling is used to block DC signals and allow AC signals to pass.