Transistor Audio Amplifier Circuit | Electronic Circuit Design by 4 Transistors

Transistor Audio Amplifier Circuit

This is a 4-transistors complementary push-pull amplifier, which is Transistor Audio Amplifier Circuit, shows the basics of audio amplifier circuit design. This transistor amplifier circuit saving on battery current, which is quite low with middle volume, rising to 25 -30mA as a volume is increased.

Transistor Audio Amplifier Circuit

This Transistor Audio Amplifier Circuit gives us a 250 mW amplifier, enough to drive a loudspeaker to the same volume as a mobile phone or MP3 player. The input must be about 100-500 mV to drive amplifier fully.  Previously, you may like LM386 amplifier circuit. But you may also like this circuit as well.

Parts Required for Transistor Audio Amplifier Circuit

First of all, You need all parts below
Q1,Q3 = BC547 or equivalent, 45V 100mA NPN Transistor,Quantity: 2
Q2,Q4 = BC557 or equivalent, 45V 100mA PNP Transistor,Quantity: 2
R1 = 56K, 1/4W Resistors tolerance: 5%,Quantity: 1
R2 = 100K, 1/4W Resistors tolerance: 5%,Quantity: 1
R3 = 33K, 1/4W Resistors tolerance: 5%,Quantity: 1
R4 = 470 ohms, 1/4W Resistors tolerance: 5%,Quantity: 1
R5 = 270 ohms, 1/4W Resistors tolerance: 5%,Quantity: 1
R6 = 1.5K, 1/4W Resistors tolerance: 5%,Quantity: 1
R7 = 10K, 1/4W Resistors tolerance: 5%,Quantity: 1
C1 = 10µF 25V,Electrolytic Capacitors,Quantity: 1
C2 = 1µF 25V,Electrolytic Capacitors,Quantity: 1
C3 = 100µF 25V,Electrolytic Capacitors,Quantity: 1
B1 = 9-volt batteries, Quantity: 1.
SP1 = 8 ohms 0.25” Speaker