Power amplifier is an useful device in audio system.
It gives power for speaker to work good.
TDA4935 is one best and is strong dual audio power amplifier IC.
People use it in bridge mode to get high power.
This Power Amplifier Circuit using IC TDA4935 show bridge design with TDA4935.
It power 8 ohm speaker with high output and low distortion.
Circuit Working:
Parts List:
| Component | Specifications | Quantity |
|---|---|---|
| Resistor | 1Ω 1/4 watt | 2 |
| Capacitor | Ceramic 220nF | 2 |
| Ceramic 100nF | 1 | |
| Electrolytic 1µF 25 V | 3 | |
| Electrolytic 100µF 25 V | 1 | |
| Electrolytic 1000µF 25 V | 1 | |
| Semiconductors | IC TDA4935 | 1 |
| Speaker 8Ω | 1 |
TDA4935 is power amplifier which make audio signal strong and it needs heat sink for cooling.
Circuit uses power from +8V to 30V DC.
Have input capacitors, feedback parts and output design for good sound.
Audio goes in at pin 7 and pin 2 through C1 and C2 which are both 1µF.
These stop DC let only AC audio pass.
For stable gain resistors R1 and R2 with 1Ω each work with capacitors C3 and C4 of 220nF, help reduce distortion and shape sound.
After amplify the sound goes to 8Ω speaker through C5 100µF.
C5 stop DC and protect speaker.
C6, C7, C8 are decoupling capacitors and they keep power clean and steady.
TDA4935 IC work in bridge mode.
Both speaker ends get signal in opposite phase and this doubles voltage and gives 4x more power than the normal design.
Formulas with Calculations:
Use these formulas to help design TDA4935 power amplifier circuit:
1. Gain (Av):
Av = Rf / Ri
where,
- Rf is the feedback resistor
- Ri is the input resistor
In this circuit gain is set by IC itself.
2. Output Power Pout:
Pout = Vrms² / Rload
where,
- Vrms is the output voltage RMS
- Rload is the speaker resistance and in this circuit it is 8Ω
3. Decoupling Capacitor Cdecouple:
C = 1 / (2π × fmin × R)
where,
- fmin is the lowest frequency to amplify
- R is the load resistance
4. Coupling Capacitor Ccouple:
C = 1 / (2π × fc × R)
where,
- fc is the cut-off frequency which is below 20Hz
- R is the input or speaker resistance
These help set power, gain and choose correct capacitor values.
How to Build:
To build a Simple Power Amplifier Circuit using IC TDA4935 follow the below mentioned steps:
- Gather all parts as in circuit diagram.
- Pin 1 of TDA4935 goes to one side of 8Ω speaker and also connect C4 + R2 in series to GND
- Pin 2 connect to pin 7 through C2
- Pin 3 connect to GND through C7
- Pin 4 and 6 connect to GND
- Pin 5 connect to +8V to +30V power and also connect C6 and C8 to GND
- Pin 7 connect to audio input through C1 and GND
- Pin 8 connect to GND through C5
- Pin 9 connect to other side of speaker and also connect C3 + R1 in series to GND
Conclusion:
Power Amplifier Circuit using IC TDA4935 is good power amp for low ohm speaker.
It is simple in design, strong sound and is great for DIY audio.
With good heatsink it gives clear and stable sound with no noise.