In short the question is: how can I get the audio from the 3.5mm port of my Raspberry Pi board to play through a small external speaker? Space is a concern in this project I will only have a few square inches and it only needs to be loud enough to be audible within ~20 feet.

More details: I'm working on a Raspberry Pi project where I want to have it play some sounds. The board itself will not be hooked up to a monitor or anything at run time so the audio will need to come through the 3.5mm jack. I raided an old clock radio to steal the speaker out of it and stripped one side of an old set of headphones so that I could connect the wires to the speaker I pulled. The sounds are playing fine through the intact earbud but when I connect the bare wires to the speaker I don't hear anything.

What can I do to get this working? Do I need some sort of amplifier? Are there better options than what I'm trying? I was hoping that the small speaker would just run off of the power coming through the headset wires.

  • \$\begingroup\$ If you want to output more power than a headphone speaker: Yeah you will need some sort of amplifier, could be as simple as a transistor, or an ic, to much more complicated full wave amplifier. \$\endgroup\$ Mar 9 '13 at 20:11
  • \$\begingroup\$ If your speaker is small enough, and in the correct ohm range you will get a small amount of sound though... But an old clock radio speaker could be designed to work in a very different range \$\endgroup\$ Mar 9 '13 at 20:12

The 3.5mm output of the raspberry Pi is a line level output. It cannot drive a speaker directly. You will need an amplifier. Headphones/Earbuds vary, but are often 32 ohm, with a power rating of half or less watts. Most small speakers are 1/2/4/8 ohms, with a power rating of 1 or more watts. The line level output just can't drive them.

You can get a simple amplifier premade, or use a audio amplifier chip like the LM386 or TPA2080D1 and a few passive components and make your own.

Alternatively, you can buy a dollar store battery powered mp3/ipod speaker and gut it, powering it off one of the Raspberry's voltage output pins.

  • \$\begingroup\$ Ok thanks. I'll see about getting the LM386 chip. \$\endgroup\$
    – William
    Mar 11 '13 at 1:57

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