With a nominal power output of around 10 watts, this 10 watt MOSFET audio amplifier circuit is intended to provide moderate power amplification for audio signals, making it appropriate for driving low impedance speakers.
To accomplish its amplification, the amplifier uses two BJT transistors BC547 in the driver stage and MOSFETs IRF540 and IRF9540 in the output stage.
This amplifier circuit offers a reliable and practical solution for audio amplification demands by utilizing the advantages of bipolar transistors for signal driving and MOSFETs for efficient power amplification.
To guarantee steady functioning and high quality audio, the circuit also combines with resistors, capacitors and a diode.
Circuit Working:
Parts List:
| Component | Value | Quantity |
|---|---|---|
| Resistors | ||
| 560 ohms | 1 | |
| 39k ohms | 1 | |
| 10k ohms | 1 | |
| Preset | 4.7k ohms | 1 |
| Capacitors | ||
| Ceramic Capacitor | 33pF | 1 |
| Electrolytic Capacitor | 1μF 16V | 1 |
| 220μF 50V | 1 | |
| 4.7μF 50V | 1 | |
| 2200μF 50V | 1 | |
| Semiconductors | ||
| MOSFET | IRF540 | 1 |
| IRF9540 | 1 | |
| Transistor | BC547 | 2 |
| Diode | 1N4001 | 1 |
| Other | ||
| Speaker | 8Ω | 1 |
In this article capacitor C1, which prevents any DC component and routes the AC audio signal to transistor Q1s base, receives the audio signal before it is introduced into the circuit.
The preamplifier is made up of the connected darlington pair of transistors Q1 and Q2.
R1 offers feedback, and preset VR1 regulates the quiescent current.
Capacitor C5 connects the output to a speaker.
The input DC decoupling capacitor, C1 is connected to the power supply filter C3.
The MOSFETs used as output are IRF540 Q3 and IRF9540 Q4.
For the positive half of the audio signal, Q3 is an N channel MOSFET and for the negative half, Q4 is a P channel MOSFET.
High efficiency signal amplification is achieved by the MOSFETs by gate driving, which is facilitated by the driver stages Q1 and Q2 output.
The 8Ω speaker, which is linked between Q4s source and Q3s drain, receives the enhanced audio signal.
In addition to blocking DC components, capacitor C5 links the audio signal to the speaker.
To ensure that the circuit operates smoothly, capacitors C3 and C4 filter out noise and regulate the power supply voltage.
Reverse voltage protection is provided by the diode D1, which improves circuit dependability.
Hence, the circuit drives the speaker with a clear, amplified output that is appropriate for moderate power applications, amplifying the audio signal from the input.
Formulas:
Below are some relevant general formulas related to the 10 Watts MOSFET audio amplifier circuit:
Power Output P:
P = VRMS2 / Rload
where,
- VRMS stands for the root mean square voltage across the speaker.
- Rload is the speakers resistance 8Ω.
Resistors for Biasing:
The base bias resistor network for Q1 is represented with R1 and R2 .
The voltage divider formula used to determine Q1s base voltage VB is as follows:
VB = VCC × R2 / R1+ R2
where,
- VCC is the supply voltage.
MOSFET Current Through:
The MOSFET current ID can be roughly represented as:
ID = VGS − Vth / RDS(on)
where,
- The gate source voltage VGS, the MOSFETs threshold voltage Vth, and its on resistance RDS(on) are represented by these values.
Value of Capacitor in AC Coupling:
The formula determines the capacitance C needed for coupling.
C = 1 / 2πfR
where,
- f is the lowest frequency of interest
- R is the load or stages impedance after it.
Drop in Voltage Throughout Capacitors:
Regarding electrolytic capacitors utilized for filtering power supplies:
Vdrop = Iload / f × C
where,
- Iload is the load current
- f is the ripple frequency
- C is the capacitance.
In order to guarantee optimal performance and operation, these formulas aid in the design and analysis of the amplifier circuit.
How to Build:
To build a Simple 10 Watts MOSFET Audio Amplifier Circuit follow the below mentioned connections steps:
- Assemble all the components as shown in above circuit diagram
- Connect collector of transistor Q1 to gate of MOSFET Q3.
- Connect base of transistor Q1 to audio input through capacitor C1 and connect resistor R1 and resistor R2 in series to ground as a biasing resistor.
- Connect emitter of transistor Q1 to base of transistor Q2.
- Connect capacitor C2 one leg to base of transistor Q1 and other leg to collector of transistor Q1
- Connect collector of transistor Q2 to center leg of preset VR1 and other leg of VR1 to positive supply through resistor R3 and diode D1.
- Connect base of transistor Q2 to emitter of transistor Q1.
- Connect emitter of transistor Q2 to ground.
- Connect gate of MOSFET Q3 to collector of transistor Q1, connect drain to source of MOSFET Q4, connect source of MOSFET Q3 to ground.
- Connect gate of MOSFET Q4 between the 2nd leg of VR1 and resistor R3, connect drain of MOSFET Q4 to positive supply, connect source of MOSFET Q4 to drain of MOSFET Q3.
- Connect capacitor C4 between resistor R3 and diode D1 to drain of MOSFET Q4.
- Connect capacitor C5 to one end of 8 ohm speaker between the junctions of drain and source of two MOSFETs Q3 and Q4 and other end of speaker to ground.
Conclusion:
To conclude, Bipolar transistors and MOSFETs are skillfully combined in the 10 watt MOSFET audio amplifier circuit to produce moderate power amplification with high efficiency and sound quality.
To maximize amplifier performance and preserve audio integrity, proper biasing, coupling and filtering are essential.
This circuit offers a reliable way to improve audio signals for a range of uses.
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