These are many simple audio amplifier circuit diagram using a transistor. Currently, ICs has been used in many audio amplifiers, especially small circuit. It is convenient to use transistors.

But when you need to use transistors, it has several advantages, such as saving you can take old equipment come to made small circuits easier than the IC.

Which may be difficult to find. Take a look at these circuits. Maybe you get the idea of it.

Here are projects::

The Simple Audio Amplifier with NO ICS

1# Low impedance mini amplifier

This circuit can apply to signal sound source that has low impedance, such as from 4-16 ohm size loudspeakers or telephone earphones that use to replace Microphones.

If using a loudspeaker replaces the rapidity will enough in sound checking that has been born from walking. The output can feed reach input of high power amplifier the other next.

Thanks: Wintec It is a 2N3904 NPN transistor. Not 2N3094 SCR. You are correct.

2# Power Amplifier OTL using AC176+AC126

Mr. Somsak is my friend who likes to make a power amplifier so much. but he does not well electronic man. I so introduce he needs to make an easy project before. This circuit is a simple power amplifier OTL that mini watt output but is an older circuit.

They use transistors example number is AC176, AC126, and BC109. which there have other a few components. They are used power Supply Voltage 9Volt only. I hope it will be once a circuit so you like and well ideas.

3# Power Amplifier OTL Cassette Radio Booster using TIP41+TIP42

This is a mini Power Amplifier OTL for Cassette Radio Booster. it has transistor TIP41 + circuits of TIP42 Drive speaker sound. Volt supply sees in the image.

4# Simple Amplifier using Transistor AC128

I find this in my old circuit electronics book. It is very a small power amplifier, but good quality audio class AB amplifier in hi-fi applications.

The component capable of delivering 2W continuously used the AC128 transistor into an 8-ohm load and 5W peak. with the proper 9-volt unregulated power supply.

5# High volt mini Amplifier with UJT transistor

This is a power amplifier circuit it works with a high voltage power supply of about 125V directly. It composes UJT transistor and transistor the ordinary. This circuit uses a transformer sing bail with then apply to high volt and uses a loudspeaker has easy. It then gets into trouble a little. You can find to decorate the popularity has of the sound with VR1 – 1M. Read the detail adds in the circuit.