In this tutorial, we are going to make a “100 Watt audio amplifier circuit”. An audio power amplifier is an electronic amplifier that amplifies low-power electronic audio signals. Such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspeakers or headphones. And a transistor audio power amplifier (that escalates the power level of the signals) will have the audio frequency range.
The practical amplifier contains a number of stages, which will amplify weak signals until the required power is obtained to activate the output device. Here 100 Watt transistor audio amplifier circuit is constructed by using transistors only (without any audio ICs). This circuit has two preamplifier transistors and four output-stage power transistors. It can be easily assembled on a commonly printed circuit board (dot PCB), or you can easily solder the circuit.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | NPN Transistor | BC108 | 2 |
| 2. | PNP Transistor | 2N6107 | 2 |
| 3. | NPN Transistor | 2N5294 | 1 |
| 4. | NPN Transistor | 2N3773 | 1 |
| 5. | Diode | 1N4007 | 2 |
| 6. | Resistor | 47KΩ,10KΩ,4.7KΩ,680Ω,22Ω,22Ω/1W 1KΩ/1W,1.5KΩ/2W,100Ω/2W,1Ω/5W | 1,2,1,2,3,1,1,1,1,1 |
| 7. | Capacitor | 4.7uf,10uf,47uf,1uf/10V,560pf | 1,1,1,1,1 |
| 8. | Connecting Wires | – | – |
| 9. | Speaker | – | 1 |
| 10. | Dual Power Supply | 35V | 1 |
Circuit Diagram
Working Explanation
As we can see in the circuit, the whole circuit has seven transistors collectively. Here two transistor (Q7, and Q6) acts as a pre-amplifier, and transistors Q1 to Q4 act as power output stage transistors. In the end, the sub-woofer loudspeaker is connected as load. Use heat sink to the power stage transistors Q1 to Q4 and utilize 100 w sub-woofer speaker, for better output response. Now we need a 35V dual power supply (+35V, Gnd, -35V) for the circuit to operate. This circuit gives better impedance in both input and output. Here check the minimum and maximum audio input range previously, do not give high voltage audio input.
Application
Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address, home audio systems, and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage, in a typical audio playback chain before the signal is sent to the loudspeakers.
