Homemade small amplifier and speaker circuit diagram

Photocoupler

First, the power amplifier

The power amplifier part adopts high-fidelity integrated block TDA1521. The peripheral circuit of the integrated circuit is extremely simple, and there are protection circuits such as overheating, squelch and short circuit, which are suitable for beginners to make. The front stage uses NE5532 for 10 times line amplification. Coupling capacitors can be made with domestic CBB capacitors or tantalum capacitors. The front stage power supply is obtained by 7815 and 7915 voltage regulation, and the power transformer should be more than 30W. The rectifier can be used with a 3A full bridge. The circuit of the power amplifier is shown in Figure 1. The circuit of the power supply is shown in Figure 2. The circuit board can be engraved with a utility knife. The power amplifier block should be filled with a large enough heat sink.

Second, the Speaker

1. Speaker unit: The tweeter uses a 3-inch tweeter for the surround box. The woofer uses a 4.5-inch speaker for car audio.

2. Box making: It can be made of medium density board with thickness of 10MM. The size is 270mm high, 170mm wide and 220mm thick. The phase guiding hole is designed at the back, so the speaker should be kept at a certain distance from the wall.