Amplifier Circuit Diagrams

150 Watt Amplifier Circuit – DIY Guide to Build Amplifier

Low Cost 150 Watt Amplifier Circuit

We’re going to make a simple 150-watt amplifier circuit in this project.


This, I believe, is the cheapest 150 Watt amplifier circuit you can build. This design, which uses two Darlington power transistors TIP 142 and TIP 147, can produce a whopping 150 W Rms to a 4 Ohm speaker. Are you ready to get rocked? Then try this.

TIP 147 and 142 are complementary Darlington pair transistors with a current rating of 5 amps and a voltage rating of 100 volts and are well-known for their durability. TIP 142, TIP 147, and TIP41 (Q1, Q2, Q3) are utilized to drive the speaker, while two BC 558 transistors Q5 and Q4 are employed as preamplifiers. This circuit is designed to be so durable that it can be assembled on a perf board or by soldering pin to pin. A +/-45V, 5A dual power source can be used to power the circuit. This is a circuit that you must try. It’s functioning perfectly!

This circuit’s preamplifier component is built around Q4 and Q5, which create a differential amplifier. The use of a differential amplifier in the input stage decreases noise while also allowing negative feedback to be applied. As a result, the amplifier’s overall performance is improved. Through the DC decoupling capacitor C2, the input signal is supplied to the base of Q5. Through the 22K resistor, the feedback voltage is provided to the base of Q4 from the junction of 0.33-ohm resistors. For driving the loudspeaker, a complementary Class AB push-pull stage is created around the transistors Q1 and Q2. The complementary pair is biassed by diodes D1 and D2, ensuring Class AB functioning. The push-pull pair is driven by transistor Q3, whose base is directly linked to Q5’s collector.

Circuit Diagram & Parts List.150 watt amplifier circuit diagram

PCBs for this project are available from PCBWay. Soon, we’ll post a sample PCB file (for download).


  • TIP 142 and 147 are Darlington pairs to remember. For clarity, they are depicted in the picture as ordinary transistors. So don’t be perplexed. Even though each one has two transistors, two resistors, and one diode, only three pins, base emitter, and collector, are visible. Internally, the rest are linked. As a result, it’s perfectly OK to treat each of them as a transistor for the sake of simplicity.
  • Use a power supply that is carefully regulated and filtered.
  • If you need volume control, connect a 10K POT in series with the input.
  • The wiring diagram does not indicate this.
  • All electrolytic capacitors must have a minimum voltage rating of 50 volts.

Power supply for this circuit.

The power source for this amplifier project is presented below as a +40/-40 unregulated dual supply. This power supply is only capable of supplying one channel; for stereo applications, double the transformer, diode, and fuse current ratings.

TIP 142-TIP 147 Pin Out Diagram with Schematics



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