Circuit: DIY AF Power Amplifier

Elektor has a long history of presenting innovative amplifer designs. Combining a classic Class-B design with short-circuit protection and up to 50W output, this durable power amplifier from 1994 is perfect for audio enthusiasts seeking reliability, simplicity, and high-quality performance.

No-Frills Power Amplifier

The "Robust A.F. Power Amplifier" article from Elektor's July 1994 issue presents a durable and straightforward design for an audio frequency power amplifier, ideal for hobbyists and audio enthusiasts alike. The amp is built around a push-pull Class-B topology, which is known for its efficiency and ability to deliver high output power. The compact design leverages cost-effective transistors, ensuring the project is accessible and affordable for a wide audience. Capable of delivering up to 50 W into a 4-Ω load, the amplifier is equipped with critical short-circuit protection to safeguard against potential misuse or accidental damage.
 

The Circuit

Key design features include a robust output stage and careful biasing to minimize crossover distortion, which is a common challenge in Class-B amplifiers. The use of negative feedback improves linearity and reduces distortion further, ensuring high-quality audio output suitable for a variety of applications.

"The construction of the amplifier should be evident from the circuit board layout and the photograph," the article about the project states. "Transistors T9, T10, T13 and T14 must be fitted with ceramic washers to keep their metal tabs isolated while still maintaining a low thermal resistance to the SK85 heatsink. T7 and T8 must also be fitted with washers (mica types are OK) on their common heatsink."
  Intended for designers with varying levels of experience, the project is approachable for beginners yet provides valuable insights for advanced users. It serves as an excellent introduction to audio amplifier design, combining theoretical explanations with hands-on construction tips. Compact and efficient, the amplifier is ideal for small-scale audio systems, DIY home projects, or as a test bench device for experimenting with other audio equipment. The project embodies Elektor’s commitment to providing practical, innovative designs that balance simplicity with performance, making it a timeless project for electronics enthusiasts.

The Original Project

The article, “Robust AF Power Amplifier,” appeared in Elektor July/August 1994. You can download this article for free during the two weeks following the publication of this news item. Enjoy the article!

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Editor's Note: This article was first published in a 1994 edition of ElektorMag. Some of the components, products, and links may no longer be available. Still, the educational content remains valuable, and we think it will inspire you at your workbench.