Op Amp Power Amplifier

This op amp circuit with explanation shows a typical power amplifier that can drive a pair of headphones or a loudspeaker. General-purpose operational amplifiers can usually deliver peak output currents of approximately 10 mA, and peak voltage swings of 10 V into a 1 kΩ load making it ideal as a low power audio amplifier. This circuit is especially suited for students because it has a single-ended power supply, which makes it very low cost and simple to build.

These types of circuits usually require an output impedance of 1 kΩ, therefore high impedance speakers or earphones are usually the best choice. If the output device has lower impedance, then we usually include a series resistor R so that the total resistance is 1 kΩ. However as you can imagine, it drastically reduces the output power reaching the speaker.