This 50 watt power amplifier circuit is designed using the complementary pair of MOSFETs. Which are IRF530 and IRF9530, an N channel and P channel mosfet. This amplifier circuit working with a dual power supply of input voltage is about ±35V, This amplifier is suitable for driving an 8-ohm, 50 watt speaker with an excellent audio clarity and low distortion. The design uses a combination of bipolar transistors and MOSFETs to achieve both high gain and efficient output power.
50 Watt Amplifier Circuit Diagram
The circuit consists of several key stages of input preamplifier, driver stage, and MOSFET output stage. The input signal is fed through a coupling capacitor and then amplified in multiple transistor stages before being passed to the MOSFET pair, which handles the final power amplification.
- Input: AUX IN (audio signal)
- Supply voltage: ±35V DC
- Output power: Around 50 watts RMS into 8Ω load
Components Required
| Reference | Value / Type |
|---|---|
| Q1, Q2 | BC556 |
| Q3, Q4 | BC546 |
| Q5 | IRF530 |
| Q6 | IRF9530 |
| R1 | 47KΩ |
| R2 | 1.2KΩ |
| R3 | 47KΩ |
| R4 | 15KΩ |
| R5 | 560Ω |
| R6 | 22KΩ |
| R7 | 4.7KΩ |
| R8 | 47KΩ |
| R9 | 2.7KΩ |
| R10 | 2.7KΩ |
| R11 | 680Ω |
| R12 | 10KΩ |
| R13 | 820Ω |
| R14 | 10Ω |
| RP1 | 1KΩ |
| C1 | 220pF |
| C2 | 47µF / 63V |
| C3 | 100µF / 63V |
| C4 | 47µF / 63V |
| C5 | 1000µF / 63V |
| C6 | 0.068µF |
| C7 | 1000µF / 63V |
| C8 | 1000µF / 63V |
| D1 | 1N4007 |
| L1 | 12 turns, 1mm copper wire |
| SP1 | 8Ω / 50W |
| J1, J2 | +35V / -35V |
| AUX IN | – |
Power Supply
This circuit operates from a dual ±35V DC power supply. Proper filtering is achieved using C5, C7, and C8 (1000µF/63V) capacitors to ensure ripple-free operation.
Use a transformer of 25-0-25V, 5A rating with a suitable bridge rectifier and large filter capacitors to build the power supply.
Additional Construction Tips
- Use a large heatsink for the MOSFETs (IRF530 and IRF9530).
- Mount transistors and MOSFETs properly insulated from the heatsink.
- Keep the input wiring shielded to avoid noise pickup.
- L1 can be wound on a 5mm air core using 12 turns of 1mm enameled copper wire.
- Use thick wires for the power and speaker output connections.
Download schematic: 50w amplifier circuit schematics.pdf
