Using a waste circuit board to make an ultra-low-cost audio

Using TDA1013B integrated blocks and used circuit boards and disassembled parts, an ultra-low-cost audio system was produced.

TDA1013B is commonly used in large-screen color TV sound system. It has a DC volume control circuit that changes according to a logarithmic curve. The power supply voltage is 10V ~ 30V. There are independent preamplification and power amplification. The power supply voltage is 14V. The load is 8Î©. The output power is 10W. Change (7) pin voltage (OV-5v), the volume can be adjusted without sliding noise.

Find a suitable scrap board, remove all parts, install three integrated circuits according to the circuit in the above figure, solder resistance-capacitance components at the corresponding positions around it, carefully add flying leads or cut the copper foil connection. The dual op amp (NE5532) in the subwoofer circuit requires positive and negative power supplies. A transformer with a height of no more than 4mm in a waste mobile phone charger can be used to form a positive and negative power supply according to the circuit in the figure. The modification of the electronic ballast for power amplifier power supply is shown in the figure below. Remove the original choke coil, the primary coil remains unchanged, and the secondary is wound with 18 coils of Ï†0.31mm enameled wire, center tapped. The diode in the picture must use fast recovery diode. The picture on the right is a dual-input switching circuit, J is a dual 12V relay, and the casing is modified with a car player.

Ultra low-cost audio circuit schematic