The LM4910 is a special chip that acts as a stereo headphone amplifier, giving you great sound quality while using very little power.
It is made for portable audio gadgets like MP3 players, smartphones and other devices that run on batteries.
This chip usually works with a low voltage of about 3.3V and has a shutdown option to save energy.
This article will go over how to design, build and understand a stereo headphone amplifier using the LM4910 chip.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistor | 20k 1/4 watt | 4 |
| Capacitor PPC | 0.39µF | 2 |
| Capacitor Electrolytic | 1µF | 1 |
| IC | LM4910 | 1 |
| Stereo Headphone | – | 1 |
The circuit runs on a 3.3V DC power source.
Audio signals from the left input and right input channels enter the integrated circuit IC LM4910 through capacitors C1 and C2.
These capacitors prevent any DC part of the signal from getting through, so only the AC audio signal goes to the amplifier.
The amplifiers gain is set by the feedback resistors R1, R2, R3 and R4 all of which are 20k in this circuit giving a balanced gain.
The IC LM4910 boosts the audio signals and sends them out through left and right output headphones.
This IC makes sure the audio output is clear and has little distortion.
Capacitor C3 which is linked to the bypass pin 5 to help cut down on power supply noise making the output signal clean and steady.
The shutdown pin 3 can turn off the amplifier to save power when the circuit is not used.
Connecting this pin to ground puts the amplifier in shutdown mode.
Formulas with Calculations:
Formulas with calculations for Simple Stereo Headphone Amplifier Circuit is mentioned below:
Gain Calculation:
Gain = R3 / R1 = R4 / R2
Since R1 = R2 = R3 = R4 = 20k, the gain is unity (1).
Cutoff Frequency:
fc = 1 / 2πRinCin
Substituting Rin = 20 k and Cin = 0.39 μF
fc = 20.4Hz
How to Build:
To build a Simple Stereo Headphone Amplifier Circuit using IC LM4910 following steps should be followed for assembling and connections:
- Gather all the components as mentioned in the above circuit diagram
- Connect the left audio input signal to pin 1 of IC LM4910 through a capacitor C1.
- Connect a resistor R1 between pin 1 and pin 8 of IC LM4910
- Connect the right audio input signal to pin 2 of IC LM4910 through another capacitor C2
- Place a R2 between pin 2 and pin 7 of IC LM4910.
- Connect a switch or jumper to pin 3 of IC LM4910 for shutdown control, to activate the shutdown mode, connect pin 3 to ground.
- Connect pin 4 of IC LM4910 to the GND
- Connect a capacitor C3 to pin 5 of IC LM4910 and ground, this stabilizes the internal bias voltage and filters noise.
- Connect the left headphone output to pin 6 of IC LM4910.
- Connect a resistor R3 between pin 8 of IC LM4910 and pin 1.
- Connect the right headphone output to pin 7 of IC LM4910.
- Connect a resistor R4 between pin 2 and pin 7 of IC LM4910.
- Connect pin 5 of IC LM4910 to a 3.3V DC power supply.
Conclusion:
The Simple Stereo Headphone Amplifier Circuit using IC LM4910 is an easy and effective way to improve sound quality in portable gadgets.
It uses very little power requires few extra parts and produces great audio making it perfect for both hobbyists and professionals who are into audio projects.
If you learn how it works and what to think about when designing it, you can tweak the circuit to fit different audio boosting needs.