5 Simple audio amplifier circuit diagram using transistor

I like to collect many circuits, including the simple audio amplifier circuit diagrams using transistors, too. Although we currently use ICs very much. Because it is small, convenient and cheap. It is convenient to use transistors. But the transistor circuit is still interesting to learn, and still charming in its uniqueness.

When you need to use transistors. It has several advantages, such as saving you can take old equipment come to make 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.

However, these circuits I have never tried to build. Therefore, I cannot confirm that it will work well. You have to be especially careful when creating it.

The Simple Audio Amplifier circuits without ICS


1# Low Impedance Mini Amplifier

This circuit can apply to signal sound source that has low impedance. Such as from 4-16 ohms 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 enter the input of the higher power amplifier the 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.

Power Amplifier OTL using AC176+AC126

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.

Simple Amplifier using Transistor AC128

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 that runs with a high voltage power supply of about 125V DC.

High volt mini Amplifier with UJT transistor

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 more detail in the circuit.

Thanks a lot, Clair Morrill said: Q1 is an N-Channel Jfet and Q2 is not a 2N numbered part but an RCA40327 transistor

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13 Comments

  1. lorenzo

    any replacement for the ac128 transistor , cause they dnt make it any more

  2. wintec

    Hi you have made a mistake with the part number for the transistors in the mini amplifier, you have 2n3094 that is a SCR,i think what you meant was 2n3904 correct me if i am wrong, THANKS.

    • MOHAMED BAHHA

      ANY NPN IS NPN AND ANY PNP IS PNP DIFFERENCE OF VOLTAGE AND AMPERES SOME TIMES THRE ARE BOOKS ABOUT SAME TRANSISTOR . ALL FOLKS . REPLACE ANY NPN WITH NPN SAME VOLTAGE . WEDONT CARE AT ALL IT ALWAYS OK .MATCH THEORY IS THE BLAK HANDICAP . AND THE BEST WAY FOR SELLERS ….

  3. michal

    Power Amplifier OTL Cassette Radio Booster by TIP41+TIP42: Good circuit! Just C1 and C2 should have opposite polarity, also I assume C3 (I used bipolar one).

  4. I built this circuit and it works well. I used a 9 volt power supply filtered with 2500uF capacitor. The output transistors should be mounted on 16 guage aluminium heatsinks approx 6 x 4 CM for each transistor. The 25k resistor can be a preset, adjust for best sound snd current. It serves me well as a Test Bench amplifier. H.L

    • Hi Joshuva,
      Thanks for your feedback.
      Oh..so good! You are happy. Which the circuit do you made it? Please tell us.

  5. Subelal ghoshle

    +12 vcc -12 vcc c2690/a715 transister with lm324 ic amp circuit add now.

  6. Clair Morrill

    in amplifier circuit #5 Q2 is a RCA 40372, which is not a 2N number

  7. Clair Morrill

    Q1 is an N-Channel Jfet, not a Unijunction Transistor (UJT), Q2 is not a 2N numbered part but RCA40327 transistor

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