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20W audio amplifier using LM1875

2016-04-17 19:51  
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This is just another 20W audio amplifier circuit , but this time based on the LM1875 audio amplifier IC from National Semiconductors. With a 25V dual power supply LM1875 can deliver 20W of audio power into a 4 ohm speaker. The LM1875 requires very less external components and has very low distortion. The IC is also packed with a lot good features like fast slew rate, wide supply voltage range, high output current, high output voltage swing, thermal protection etc. The IC is available in TO-220 plastic power package and is well suitable for a variety of applications like audio systems, servo amplifiers, home theatre systems etc.

Circuit diagram.


Assemble the circuit on a good quality PCB. Use +/-25V DC dual supply for powering the circuit. K1 can be 4 ohm, 20W speaker. A proper heat sink is necessary for the IC. F1 and F2 are 2A fuses.