Audio Amplifier Circuit Diagram
The major circuitry is contained in the amplifier module. C1 is the input coupling capacitor
and blocks DC signal, so does C3 which is the output coupling capacitor, and C2 which
blocks DC from the feed back loop to the differential input. R2 and R3 set the level of feed
back. C4 and R4 provide a high frequency load for stability where loudspeaker inductive
reactance may become excessive. C5 and C6 provide power supply decoupling or filtering.
There should be no problems with the stability of the circuit, however if you do, make sure
the power supply filtering and leads are adequate. If necessary you might connect an RC
compensation network between IC pins 2 and 4 as in the data sheet. Values for Cx of 22 -
33 nF and for Rx of 39 - 47 ohms, should be satisfactory whilst still maintaining satisfactory
high frequency response.
The gain is equal to 1 + (R2/R3) = 101, or 40 dB, minus any input attenuation. You may
reduce the overall gain by increasing the value of R3 if you are only able to use part of the
potentiometer range as a volume control. For example, an R3 of 10 ohms will give a gain of
23 (27dB).
Parts List
The parts list of this project is as shown below.
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