The Circuit Schematic Diagram of Simple 500 mW 3 Transistors Audio Amplifier

The following schematic shows a simple small 3 transistors audio amplifier circuit suitable for small battery powered devices :

500 mW 3 transistors audio amplifier circuit schematic

500 mW 3 transistors audio amplifier circuit schematic diagram

Due to its simplicity, this circuit is very suitable for the DIY amplifier starter. Both the input and output of this circuit are dc-blocked since this audio amplifier only process audio signal (not a dc amplifier). It is blocked using capacitor. The schematic shows two 3.3 ohm resistors are connected to the emitters of PNP-NPN transistor couple to stabilize the transistor gain. Therefore the temperature change won’t much affect the performance. To replace the final transistors, any PNP-NPN transistor with identical performance that capable of handling 100mA collector current should be suitable. At maximum, the voltage swing will be around 2 Volts, therefore the current at 8 ohm speaker will be 0.25A, and the maximum power would be 0.5 Watts. [Bill Bowden’s Circuit Collection]

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