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40W amplifier using TDA1514 Schematic circuit diagram


Here’s another addition to the array of audio amplifier circuits—a 40W amplifier utilizing the TDA1514, a high-performance hi-fi amplifier chip developed by Philips. This IC boasts a range of valuable features, including thermal protection, a mute-standby function, and minimal harmonic distortion. Operating with a dual +25/-25 V DC power supply, this amplifier is capable of delivering a robust 40 Watts of output power when connected to an 8-ohm speaker.

To initiate the amplification process, the audio signal is introduced into pin 1 of the IC, with capacitor C2 serving as a crucial DC decoupling component. The closed-loop gain of the amplifier can be adjusted within the range of 20 to 64 dB by altering the values of resistors R3 and R4. The inclusion of resistor R2 and capacitor C4 creates a Zobel network, which effectively rectifies loudspeaker impedance issues and enhances the overall frequency response.

Incorporating resistors R7, R6, and capacitor C5 forms a bootstrapping mechanism. However, if bootstrapping isn’t necessary, these components can be omitted, and pin 7 can be directly connected to pin 6. It’s worth noting that this modification will reduce the output power by approximately 10%.

Lastly, R1 functions as the input bias resistor, influencing the input impedance of the amplifier.

Circuit diagram

40W amplifier using TDA1514 Schematic circuit diagram


  • Assembling the circuit on a good quality PCB will improve the sound quality.
  • Use a +25/-25V DC, 4A dual power supply for powering the circuit.
  • K1 can be an 8-ohm, 50W loudspeaker.
  • IC1 must be fitted with a proper heat sink.

The TDA1514 integrated circuit is a hi-fi power amplifier for use as a building block in radio, tv, and other audio applications. The TDA 1514 circuit is totally protected, and also has a mute function that can be arranged for a period after power-on with a delay time fixed by external components. The device is intended for symmetrical power supplies but an asymmetrical supply may also be used. For stereo, amplifier configuration uses two identical circuits.


  • High output power
  • Low harmonic distortion
  • Low intermodulation distortion
  • Low offset voltage
  • Good ripple rejection
  • Mute/stand-by facilities
  • Thermal protection
  • Protected against electrostatic discharge
  • No switch-on or switch-off clicks
  • Very low thermal resistance
  • Safe Operating Area (SOAR) protection.

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