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Simple Stereo Headphone Amplifier Circuit using IC LM4910

LM4910 IC is special chip.

It makes stereo headphone sound good by using a very low power.

The circuit is useful for small devices like MP3, phone, battery gadgets.

It work on low voltage to around 3.3V and has shutdown mode to save power.

This article for Simple Stereo Headphone Amplifier Circuit using IC LM4910 shows how to design, build and understand stereo amp with IC LM4910.

Circuit Working:

Parts List:

ComponentSpecificationQuantity
Resistors20k 1/4 watt4
CapacitorsPPC 0.39µF2
Electrolytic1µF1
SemiconductorsIC LM49101
Stereo Headphone1

Circuit uses 3.3V DC power.

Audio come from left and right input and goes through capacitors C1 and C2 into LM4910 chip.

C1 and C2 blocks DC and only lets AC audio signal pass to amp.

Gain sets by resistors R1, R2, R3, R4 which are all 20k and give a balanced gain.

LM4910 boost signal and send to left and right headphone out.

Audio is clear and with low distortion.

Capacitor C3 connects to pin 5 bypass, reduces power noise and keep output clean.

Pin 3 is shutdown pin which connects to ground to turn OFF the amp and save power.

Formulas with Calculations:

Here are formulas and calculations for Simple Stereo Headphone Amplifier Circuit:

Formula for Gain:

Gain = R3 / R1 = R4 / R2

All resistors are 20k so:

Gain = 20k / 20k = 1 (unity gain)

Cutoff Frequency:

Formula:

fc = 1 / (2 × π × Rin × Cin)

where:

Rin is 20k
Cin is 0.39μF

fc = 1 / (2 × 3.14 × 20000 × 0.39×10⁻⁶)

fc = 20.4 Hz

So low signals below 20.4 Hz are blocked.

How to Build:

To build a Simple Stereo Headphone Amplifier Circuit using IC LM4910 following steps should be followed for assembling and connections:

Conclusion:

This project for Simple Stereo Headphone Amplifier Circuit using IC LM4910 is small, easy and works well.

It uses low power, need few parts and give clear sound.

Its good for hobby and for professional audio work.

We can change design for different sound as per our needs.

References:

LM4910 headphone amplifier noise source

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