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Operational amplifier AC amplifier

A small adjustable and multipurpose class A amplifier which can be used to pre amplify the signals before giving into power amplifiers.

In this tutorial, we are designing an AC amplifier using operational amplifier. The basic amplifying action of the operational amplifiers remains same as stated in dc amplifier section also. But that type of amplifier is only to amplify the small dc values. In AC amplifiers Q point(operating point value) is very important. Q point is basically a DC value (on DC load line) over which the ac signal is superimposed for the faithful amplification. This value Q point is generally a mid-value to get the maximum signal efficiency.

Here we can set the Q-point in case of audio amplifier to adjust the signal to power efficiency ratio. These points are categorised as classes (A, B, AB, C). In below given graph you can see the all. But here the operational amplifier is used to amplify small signal superimposed on a DC signal.

That’s why here we are setting the operating point in middle so there will be no loss of signal, the maximum faithful amplification is possible.

Components required:
- LM358 operational amplifier
- Resistors (1K and 10K)
- Potentiometer (100K)
- Custom PCB from JLCPCB
- Power supply (5V)”

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