electronics-amplifier tutorial

This is 2x1W mini audio amplifier circuit using IC KA2209. It will operate well from 3-12V DC and will work from a battery since the quiescent current drain is low. It requires no heat sink for normal use. The input and output are both ground referenced. Maximum output will be obtained with a 12V power supply and 8 ohm speaker, however it is particularly suitable for driving headphones from a supply as low as 3V

The mini amplifier circuit only a few external components, the IC contains most of the necessary circuitry. R1,R2 and R3,R4 are the feedback resistors. C1 provides power supply decoupling. C2 and C3 are the input coupling capacitors, which block any DC that might be present on the inputs. C4,C5 block DC in the feed back circuit from the inverting inputs, and C6,C7 are the output coupling capacitors. C8, R5 and C9,R6 act as zobel networks providing a high frequency load to maintain stability at frequencies where loud speaker inductive reactance may become excessive. The pot provides adjustable input level attenuation.

KA2209 - Audio Amplifier Circuit Component

C1,C2,C3    : 10 uF/25V  ecap
C4,C5       : 100 uF/16V ecap
C6,C7       : 470 uF/16V ecap
C8,C9       : 100 nF     poly
R1,R3       : 1k     Resistor
R2,R4       : 100R   Resistor
R5,R6       : 4R7ohm Resistor
Pot1        : 10k dual gang log pot
IC1         : KA2209 Integrated Circuit