This article provides an information about how to make an audio amplifier using an opamp. We will also try to explain the working of this audio amplifier using an opamp.
We have already studied some important applications of the operational amplifier such as op-amp comparator, op-amp integrator in the previous articles. Today we are going to learn another important application of op-amp as an audio amplifier and its working.
We know that the output of most of the communication receivers is the audio amplifier. Important characteristics of the ideal audio amplifier are listed below.
- High gain.
- Distortion should be minimum in the audio frequency range. (20Hz to 20KHz)
- Input resistance or impedance should be very high.
- Low output resistance to provide optimum coupling to the speaker.
If we use the operational amplifier in the audio amplifier, then it will cover all the characteristics listed above so as to make an ideal audio amplifier.
The following figure shows the circuit diagram of the audio amplifier using operation amplifier.
Working of audio amplifier
It should be noted that the op-amp is supplied only from +V volt power supply (usually 5V power supply), the –V terminal is grounded. This arrangement is made so as to get the output in the range (+V-1) volt and +1 volt. In audio amplifier coupling capacitor (Cc2) is used between the op-amp and speaker. The coupling capacitor is necessary to reference the speaker signal around the ground. The capacitor Cs is included in the Vcc line to prevent any transient current caused by the operation of op-amp from being coupled back to Q1 through the power supply.
Op amp (IC 741) pin configuration
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