The TDA1521 Audio Power Amplifier Board is a dual-channel DIY stereo amplifier module offering a stated 2 × 15W output for compatible speakers. It features an integrated rectifier and filter circuit, allowing connection to a suitable transformer-based power supply. The module is ideal for DIY audio systems, speaker modification, desktop amplifiers, and electronics projects. A sufficiently large heat sink is required before testing or operation to ensure proper heat dissipation and stable performance.

The 12V DC to 220V AC 40W Step-Up Inverter Module converts 8V–13V DC input into approximately 220V AC output using a high-frequency switching circuit. With a compact 43 × 38 × 25mm design and 40W rated power, it is suitable for DIY inverter projects, battery-powered systems, compatible LED lights, and energy-saving lamps. The output is a high-frequency square wave, so it is not suitable for motors, fans, coils, or other incompatible inductive loads. Do not overload or short-circuit the output, and use proper high-voltage safety precautions.