1 9V Amplifier Circuit

Another simple amplifier circuit powered by 9V battery. You can use this for your mp3 players, phone and other audio devices. The circuit can be assemble in a very small size since it has less parts.
amplifier schematic
NA22E, BC369 pinout
2N2222, NA21E, BC368 pinout
Part List:
R1 - 100 kilo ohms 1/4W
R2 - 1 kilo ohms 1/4W
C1 - 33uF electrolytic capacitor rated 10V
C2 - 220uF electrolytic capacitor rated 10V
D1, D2 - 1N914 or similar diode
Q1 - 2N2222 NPN transistor
Q2 - NA22E, BC369 or similar PNP transistor
Q3 - NA21E, BC368 or similar NPN transistor
Spk - 4 ohms to 8 ohms speaker (2W)

Other useful amplifiers:
Simple Hearing Aid - small amp powered by 1.5V
USB amplifier - usefull for computer or laptop speakers


  1. can you tell me how the circuit function..i really need an idea because i will explain the direction of signal from input to output...