Project: USB/9V Mini Speaker

Discussion in 'The Completed Projects Collection' started by tjohnson, Jan 8, 2016.

  1. tjohnson

    Thread Starter Active Member

    Dec 23, 2014
    I built this mini speaker:
    Mini Speaker.jpg

    Parts List
    • 1 x mini PCB
    • 1 x 8-ohm speaker
    • 1 x LM386 chip
    • 1 x 8-pin IC socket
    • 1 x 10-ohm resistor
    • 1 x 330-ohm resistor
    • 2 x 1k-ohm resistor
    • 2 x 220uF capacitor
    • 1 x 10k-ohm logarithmic pot
    • 1 x knob for pot
    • 1 x 3.5mm stereo headphone cable
    • 1 x USB cable
    • 1 x 9V battery connector
    • 1 x 9V battery
    • 1 x SPDT on-on switch
    • 1 x LED




    This project is basically a combination of two Instructables (LM386 Audio Amplifier and USB Powered Speaker) with a few modifications. It has a dual power source: the switch toggles between a 5V USB port and a 9V battery. If the USB cable is not plugged in and the switch is connected to the USB power source, the circuit will be open. I added the LED as a power indicator to remind me to disconnect the switch from the battery when not in use.

    I didn't have a spare headphone cable, so I bought some flimsy earbuds at a dollar store for $1, cut the cable off, and trashed the speakers. For the USB cable, I used a phone charging cable with a broken mini-USB connector that I cut off. The speaker I used is model GF0576 and is available from Digi-Key.

    No special tools are required for this project; only wire, a soldering iron, and solder. The IC socket is technically optional, but it's really a requirement unless you have excellent soldering skills. When I made my first prototype I didn't use one and ended up blowing out the LM386 chip. The knob for the pot is also not strictly required, but it's certainly nice to have.

    For a project enclosure, there are many hard plastic ones sold by RadioShack and other electronics suppliers, and Altoids tins are also commonly used. I don't have a good power tool to drill holes in a hard enclosure, so I used a small plastic food container that I could cut with scissors and a knife. This isn't as sturdy, but it shows that almost any small container lying around the house should work if it's large enough for the components to fit inside it.


  2. JohnInTX


    Jun 26, 2012
    Scott has a point about the pictures as a documentation tool, they could be clearer. It is hard to get a good depth of field sometimes. It would be handy to spread the components out a bit if possible so that the input cable to pot wiring is more visible. That's picking nits, though. With the parts list, schematic and pic of it assembled, even someone with modest skills should be able to replicate the project. I like the use of the poly bowl - easy to work with and cheap too.
    Nicely done.
    Monika Verma and tjohnson like this.