Audio Power Amplifier with TDA2050

This project is an audio amplifier based on TDA2050 and LM1875.


This is not an ordinary project, but an attempt to make a PCB that is suitable for TDA2050 and LM1875 and has all the necessary circuitry on board – power supply, speaker protection, delayed turn-on and fast turn-off. This is achieved using the convenient uPC1237 IC.

TDA2050 and LM1875 are pin to pin compatible, the differences in their schematics are the values of a couple resistors and one capacitor. All this allows to make an universal circuit board, suitable for any of these two ICs.

It is 2x30W, but it depend of the power supply voltage and the impedance of the speakers connected to the output.


download schematic in PDF


Parts List

B1 KBU8M FBU4 C1 100nF C050-024X044 C2 100nF C050-024X044 C3 1000uF E5-10,5 C4 1000uF E5-10,5 C6 2.2uF C050-075X075 C7 220nF C050-030X075 C8 22uF E3,5-8 C9 100nF C050-024X044 C10 100nF C050-024X044 C11 1000uF E5-10,5 C12 1000uF E5-10,5 C13 4.7uF E2,5-6 C14 2.2uF C050-075X075 C15 220nF C050-030X075 C16 22uF E3,5-8 C17 4700uF E7,5-18 C18 4700uF E7,5-18 C19 47uF E2,5-7 C20 22uF E3,5-8 C21 22nF C050-025X075 D5 1N4148 DO35-7 D6 1N4004 DO41-10 D7 BZX85C12V DO41Z10 H1 MOUNT-PAD-ROUND3.0 3,0-PAD IC1 LM1875 T05D IC2 LM1875 T05D IC3 UPC1237 SOP8 IN 6410-02 IN1 6410-02 J1 OUT1 AC2 J2 OUT2 AC2 J3 AC AC3 JP1 JP1 K1 G2R2 G2R2 LED 6410-02 LED2 LED5MM LED3 6410-02 R1 1k 0207/2V R2 20k 0207/12 R3 22k 0207/7 R4 1M 0207/7 R5 1R 0414V R6 1k 0207/2V R7 20k 0207/12 R8 22k 0207/7 R9 1M 0207/7 R10 1R 0414V R11 2k2 0207/7 R12 120k 0207/7 R13 120k 0207/10 R14 56k 0207/7 R15 9k1 0207/7 R16 10k 0207/7 R17 92k 0207/10 R18 330R 0207/10 R19 68k 0207/7 R20 3k9 0207/10 R21 10k 0207/7 T2 MPSA42 TO92-EBC



PCB Design

PCB top layer – Download in PDF 

PCB bottom layer – Download in PDF or mirror

Photo of the PCB bottom layer






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