One Inch Squared - Portable Headphone Amplifier

Portable headphone amplifier with built in LiPo battery charger.

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Description

Portable headphone amplifier that runs on a single cell LiPo battery (3.7V) and features a LiPo battery charger on board.

Details

I chose the Texas Instruments LM4881 audio amplifier because it requires a minimum number of external components and features digital volume control. The total cost of components for a single amplifier is $21.99 ($16.99 for components from Digikey + $5 for PCB from OSH Park)

Components

1 × LM4881 Audio ICs / Audio Amplifiers
1 × ne555psr Clock and Timer ICs / Timer ICs
1 × 180k resistor 0603
1 × 150k resistor 0603
1 × 1uF capacitor 0603 Electronic Components / Misc. Electronic Components

View all 25 components

Project Logs

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Choosing an Amplifier IC
ww • 12/20/2015 at 23:41 • 0 comments

I've considered numerous amplifier IC's, but I settled with the Texas Instruments' LM4811. The IC's small footprint and low number of external components required made it the perfect candidate for a size restricted design. The LM4811 also featured digital volume control, which means I won't need to include a clunky potentiometre to provide volume control! However, TI suggests using a microcontroller to handle the digital volume control. Microcontrollers are expensive and need to be programmed, so I came up with an alternative, which I will explain in a later log.
http://www.ti.com/lit/ds/symlink/lm4811.pdf