Custom Audio Amp

JacksonS

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This is a small audio amp made for small portables. The circuit board is 21 mm X 24 mm. I got them from OSHpark and hand-soldered all the components. This is the ideal amp for me since I can never find a good, low-wattage amp to buy for my projects.

Technical features:
- 2W stereo speaker output
- 150 mW stereo headphone output
- 5v to 3.3v power input
- 32-step digital volume control using up and down buttons

One notable feature is that the headphone output is completely separate from the speaker output, so this amp can be used with small headphone jacks, like those found in smartphones. The headphone jack just needs to have one switch for sensing, as most of them do.
 

ShockSlayer

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I really like this. Solves all the common problems with audio amps in portables in one go.
 

JacksonS

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The 8-pin chip is a PIC microcontroller that communicates via I2C to control volume. The headphone and speaker volume can be controlled independently so it's kind of customizable in that way. The main IC is a headphone/speaker amp combo from TI that comes in a QFN package. Most other low-wattage amps like this come in BGA packages.
 
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What differentiates this from the standard PAM8403?
I'm only asking because I have a couple of those already, and don't know if I should use them.
 

Aurelio

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What differentiates this from the standard PAM8403?
I'm only asking because I have a couple of those already, and don't know if I should use them.
The PAM8403 is a single-ended amplifier (which is suitable only for speakers, not headphones), while this is both for speakers and headphones. Also it has digital volume controls
 
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