• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Need circuit help? Post them in the comments! I've answered over 50,000!

Blog | Categories | About | Contact | Calculators-online
You are here: Home / Audio and Amplifier Projects / Hi-Fi 100 Watt Amplifier Circuit Using 2N3055 Transistors – Mini Crescendo
warning message: electricity is dangerous, proceed with caution
powe supply

Hi-Fi 100 Watt Amplifier Circuit Using 2N3055 Transistors – Mini Crescendo

Last Updated on December 22, 2023 by Swagatam 205 Comments

Video Demonstration of the Crescendo Amplifier

The mini crescendo 100 watt transistorized amplifier circuit explained here was built and tested by me and am extremely pleased by its performance and also its ruggedness as far as maintenance and handling is concerned.

Table of Contents
  • Video Demonstration of the Crescendo Amplifier
  • Amplifier Class
  • Circuit Operation
  • How to Set Quiescent Current
  • Power Supply Circuit

Amplifier Class

Basically, the entire configuration is a symmetrical class A amplifier incorporating an input filter stage, an intermediate driver stage and a powerful symmetrical output stage consisting of the versatile 2N3055 power transistors.

The circuit efficiently drives a 100 watt 4 Ohms speaker with inputs derived from any audio source like a cell phone or DVD player etc.

Before you learn how to build this interesting and useful 100 watt amplifier circuit using 2N3055 transistors, a prior understanding of the involved circuit configuration would be very handy, let’s begin the explanation with the following points:

Circuit Operation

A quick glance at the given circuit diagram makes us conclude that the output configuration is not symmetrical, since the transistors T15 and T16 are both NPN types.

The input stage of the circuit begins or initiates with a symmetrical differential preamplifier stage consisting of the transistors T1, T2 and T3, T4.

T5 and T6 are positioned as the current sources which are further extended as the driver stage consisting of the transistors T7 and T8.

However a closer inspection tells us that of course the wiring is symmetrical, having the transistors T11, T13, T15 at the upper section acting like special booster transistor package.

Similarly the lower section also employs identical super booster stage consisting of the transistors T12, T14 and T16.

The above two sections are perfectly complementary to each other, with reference to the diagram which indicates their emitters being terminated to a common point through the resistors R25 to R27 and via R28 to R30, this effectively that the wiring is exclusively symmetrical by nature.

The output stage is able to produce a massive 200,000 times amplification factor with comparatively very low quiescent current drain.

The quiescent can be set by the adjusting the preset P1.

Due to a non critical nature of the circuit, the entire project can be easily built over a general purpose PCB, however the layout of the components or rather the placement and the ratio of the distance of the components must be kept as identical as possible to the layout of the circuit diagram.

Though a common heatsink may be used for the entire set of the output devices, I personally used separate individual heatsinks for each of the transistors.

This saved me from the headache of using the cumbersome and low efficient mica isolation kit between the transistors.

The inductor is kept for improving the dynamic nature of the circuit. It is built by winding 20 turns of super enameled copper wire over the 1 Ohms resistor itself.

The wire is selected to be close to 1mm in thickness.

Though not absolutely necessary, for better thermal stability the transistors T9 and T11 and also T10 and T12 should be glued together, preferably by attaching the respective pairs face to face.

The quiescent current should be ideally set to 50 mA through the following initial procedure:

60 watt crescendo amplifier circuit

How to Set Quiescent Current

1) Remove the speakers, and short the input terminals (across R1),

2) Connect a DMM set at current range in series with the positive of the power supply to the circuit,

3) Next adjust the preset such that the meter reads an input of 50mA, that’s all, the amplifier’s quiescent current is set and now the connections may be restored for the normal operations of the system.

Power Supply Circuit

The power supply circuit is also shown along side and as can be seen there’s nothing special about it and may be built using the shown ordinary sets of components.

mini crescendo power supply circuit

Parts List of 100 watt amplifier circuit (sh0wn below)

  • R1 = 430 K,
  • R2 = 47K,
  • R3 = 330 Ohms,
  • R4, R5 = 12 K ,
  • R6, R7, R20, R21, R22, R23, R24 = 1 Ohm, 3 Watt, Wire Wound Type,
  • R8, R17 = 68 Ohms,
  • R9 = 100 K, R10, R11, R12, R13 = 5K6,
  • R14, R15 = 12 K,
  • R16, R19 = 100 Ohms,
  • R25 = 10 Ohms / 2 Watts,
  • P1 = 100 Ohms Preset, Linear,
  • C1 = 1 µF / 25V,
  • C2 = 1 n, CERAMIC,
  • C3, C4 = 100PfC5 = 100 nF,
  • C6, C7 = 1000 uF / 35 V,
  • L1 = 20 turns of enameled 1mm copper wire over R24,
  • D1, D2 = RED LED 5mm, All other diodes are = 1N4148,
  • T1 = Matching BC546 pair,
  • T2 = Matching BC556 pair,
  • T3 = BC 557B,
  • T4, T7, T8 = BC 547B,
  • T5, T12 = BC 556B,
  • T6, T9 = BC 546B,
  • T10 = BD 140,
  • T13 = BD 139,
  • T11, T14 = 2N 3055
  • General Purpose PCB,
  • All the transistors T10, T13, T11 and T14 ae mounted on suitable heatsinks

The original design, (courtesy - elektor electronics)

100 watt mini crescendo amplifier circuit

The MOSFET version of the above design can be witnessed in the below given image:

120 watt mini crescendo amplifier circuit

For the complete construction details, please refer to the following link:

Mini Crescendo pdf with PCB and protection circuits 

You'll also like:

  • 1.  Guitar Distortion Generator Preamplifier Circuit
  • 2.  32 watt Amplifier Circuit using TDA2050
  • 3.  Using Electret Microphone on Computer PC
  • 4.  Simple Mini Audio Amplifier Circuits
  • 5.  Power Amplifier Circuit using IC 741 and MOSFET
  • 6.  How to Make an Outstanding Home Theater System

Filed Under: Audio and Amplifier Projects Tagged With: 100, 2N3055, Amplifier, Mini, Transistors, Watt

About Swagatam

I am an electronics engineer and doing practical hands-on work from more than 15 years now. Building real circuits, testing them and also making PCB layouts by myself. I really love doing all these things like inventing something new, designing electronics and also helping other people like hobby guys who want to make their own cool circuits at home.

And that is the main reason why I started this website homemade-circuits.com, to share different types of circuit ideas..

If you are having any kind of doubt or question related to circuits then just write down your question in the comment box below, I am like always checking, so I guarantee I will reply you for sure!

Previous Post: « 3 Glittering LED Christmas Tree Light Circuits Explored
Next Post: 4 Automatic Day Night Switch Circuits Explained »
Subscribe
Notify of
guest
guest
205 Comments
Inline Feedbacks
View all comments

Primary Sidebar

circuit simulator image

Subscribe to get New Circuits in your Email

Categories

  • Arduino Projects (90)
  • Audio and Amplifier Projects (132)
  • Automation Projects (17)
  • Automobile Electronics (101)
  • Battery Charger Circuits (84)
  • Datasheets and Components (105)
  • Electronics Theory (140)
  • Free Energy (38)
  • Games and Sports Projects (11)
  • Grid and 3-Phase (19)
  • Health related Projects (25)
  • Home Electrical Circuits (12)
  • Indicator Circuits (15)
  • Inverter Circuits (89)
  • Lamps and Lights (142)
  • Meters and Testers (71)
  • Mini Projects (46)
  • Motor Controller (64)
  • Oscillator Circuits (28)
  • Pets and Pests (15)
  • Power Supply Circuits (89)
  • Remote Control Circuits (50)
  • Security and Alarm (64)
  • Sensors and Detectors (103)
  • SMPS and Converters (31)
  • Solar Controller Circuits (60)
  • Temperature Controllers (42)
  • Timer and Delay Relay (49)
  • Transmitter Circuits (29)
  • Voltage Control and Protection (38)
  • Water Controller (36)

Other Links

  • Privacy Policy
  • Cookie Policy
  • Disclaimer
  • Copyright
  • Videos
  • Sitemap

People also Search

555 Circuits | 741 Circuits | LM324 Circuits | LM338 Circuits | 4017 Circuits | Ultrasonic Projects | SMPS Projects | Christmas Projects | MOSFETs | Radio Circuits | Laser Circuits | PIR Projects |

Social Profiles

  • Twitter
  • YouTube
  • Instagram
  • Pinterest
  • My Facebook-Page
  • Quora
  • Stack Exchange
  • Linkedin
  • Recent Comments

    • Swagatam on Simple Buck Converter Circuits using Transistors
    • David on Simple Buck Converter Circuits using Transistors
    • Swagatam on Clap Switch Circuits with Relay ON/OFF: [Tested]
    • Mark on Clap Switch Circuits with Relay ON/OFF: [Tested]
    • Swagatam on Boost Converter Calculator

    © 2025 · Swagatam Innovations