This is small 1 Watt Hi-Fi Amplifier Circuit give 1 watt sound power.
It is good for small speaker or DIY audio project.
The sound quality is clear and nice and even power is low.
This type of circuit are easy to build and does not need many parts.
What is a 1 Watt Hi-Fi Amplifier Circuit:
1 watt Hi-Fi amplifier circuit is one electric circuit to make Hi-Fi sound better.
It give around 1 watt power.
Hi-Fi amplifier make sound low but very clear and nice.
This 1 watt amplifier is mostly used in small audio system, desktop speaker and headphone amplifier.
Circuit Working:
Parts List:
| Component | Value | Quantity |
|---|---|---|
| Resistors all resistors are 1/4 watt | ||
| 68Ω | 1 | |
| 1M | 1 | |
| 1Ω | 2 | |
| 1k | 1 | |
| Potentiometer 5k | 1 | |
| Capacitors | ||
| Electrolytic 4.7µF, 250µF,100µF | 1 each | |
| Semiconductors | ||
| Transistors 2N3904, 2N2430, 2N2706 | 1 each | |
| Speaker 4Ω | 1 | |
| Battery / DC Supply 9V | 1 |
This 1 watt Hi-Fi amplifier circuit uses same kind of output stage like modern sound system with NPN and PNP power transistors.
Steps how circuit work are below:
When input signal come in it goes to volume control RV1 and this RV1 work like knob which make signal strong or weak.
Then this signal connects to first stage of transistor Q1 and then Q1 take signal from volume control and make it more strong.
Speaker and resistors R1 and R5 are connected to Q1s collector.
Voltage here is around 4.5V which is half of total power.
When voltage is 4.5V, emitters of Q2 and Q3 join at same point.
Resistors R3 and R4 they have low value and control how much current pass through Q2 and Q3.
If signal from Q1 is below 4.5V then Q2 is ON and Q3 is OFF.
If signal goes above 4.5V then Q2 turn OFF and Q3 turn ON.
Q2 and Q3 send strong signal from their emitters and join together and connects through capacitor C2 and this capacitor send sound to loudspeaker.
To keep sound clean and stable feedback is used.
Resistors R5 and R2 help with this and by making gain a little low.
Sometimes thermistors or diodes are used in modern design to stop heating and protect the transistors but here resistor R1 give base bias to Q2 and Q3.
Output:
Even this circuit is small and little hard it gives strong 1 watt sound with low noise.
Sound quality stay good like hi-fi system.
Formulas:
We can make 1 watt Hi-Fi amplifier circuit using simple transistor circuit with all parts shown in circuit diagram above.
Here is basic formula to find power:
P = Vpeak² / Rload
where:
- Vpeak is top voltage of signal means peak voltage
- Rload is speaker resistance like 4 ohm
Using this an easy method and anyone can build 1 watt Hi-Fi amplifier with transistors and other parts shown in this article.
Some changes may be needed based on what parts we have, what we want and how we want circuit to work.
Advantages and Disadvantages:
Advantages:
- This circuit is good for modern sound system where space is small and output stage save space.
- It give 1 watt sound with very low noise so sound quality is very good.
- Biasing and negative feedback make circuit stable and help protect output transistors from damage.
Disadvantages:
- Circuit use DC coupling so if one transistor change or goes bad whole circuit can stop working right.
- To fix this problem better to use same type of matched pair of transistors in output stage.
How to Build:
Below mentioned are the connection steps for building the 1 watt Hi-Fi amplifier circuit:
- To make circuit work good first choose matched NPN and PNP power transistors for output stage.
- To change how strong signal is connect input signal to volume control RV1.
- Then send signal through capacitor C1 as it block bad DC from going in.
- Next send clean signal to base of Q1 which is the first amplifier transistor.
- Now connect loudspeaker and Q1 collector load using resistors R1 and R5 to begin output stage.
- Use resistors R3 and R4 to control current that connects through Q2 and Q3.
- When signal is around 4.5V circuit will decide when to switch between Q2 and Q3.
- Use resistors R5 and R2 to give negative feedback and this help will make circuit more stable and reduce noise.
- For base bias of Q2 and Q3 use resistor R1 or can also use thermistors or diodes to stop heating problem.
- At at end connect big capacitor C2 to the speaker and it will carry final strong signal to speaker.
Conclusion:
This small but smart 1 watt Hi-Fi amplifier circuit now used in many modern sound systems.
Designers like it because it is stable, small in size and make sound with very low distortion.
Anyone can try this circuit and learn more about how to build and improve circuits.
If anyone need help or have question feel free to ask anytime!