Here the simple and low cost audio amplifier schematic diagram. The circuit is ideal for a pocket radio or other hand held audio equipments.
The first part of the circuit here is a preamplifier consisting of transistor Q1(2N2222). The collector of the Q3 is coupled to the base of Q2 (2N2905A),which forms a complementary symmetry pair with Q3 (2N3053). The amplified signal is available at the junction of emitter of two transistors.
- For Q1 you can try with any general purpose NPN transistors like BC107, BC148,etc.
- For Q2 and Q3 you can try any complimentary power transistors. The result may vary slightly. No problem.
- The can be also powered from a well regulated and filtered 9V DC power supply.