Adding a speaker to PocketC.H.I.P. is a great way to start extending its hardware. Jose, one of the NTC electrical engineers, completed the hack in about 5 minutes and got everyone in the office excited about adding a speaker to their PocketC.H.I.P.s.
Modifying a new computer with custom circuitry and solder might seem intimidating or risky, but this project is accessible to everyone. Parts cost around $5.00 and should take about 30 minutes to build if you’re a beginner. If you get stuck or have questions, make sure to post them in our forums and be as detailed as possible.
All of the parts used in this project are fairly easy to source, but below you’ll find direct links to what we used in the project.
- 30AWG wire, often called “wire wrap.” Wire wrap comes in spools and pre-cut lengths. While buying a spool may seem like a more cost effective purchase, cutting and stripping these tiny gauge wires can be difficult. If you don’t want to buy an expensive wire stripper, buying pre-cut lengths of wire wrap wire is a decent alternative. Here’s another source.
- 8Ω speaker – since the speaker needs to fit inside the PocketC.H.I.P. enclosurer, look for a small diameter speaker ~23mm.
- 3W Amplifier – Jose suggests using this 3W amplifier to keep things simple.
- Kapton tape – if you don’t have kapton tape, masking tape or electrical tape are decent replacements for this application.
- Soldering iron & lead free solder
- Hot glue gun & glue
- Needle nose pliers
- Wire cutters
- Wire stripper – you’ll need a good pair to strip 30 AWG wire wrap wire. An alternative is to buy pre-cut lengths of wire wrap. See the parts section for a recommendation.
1. Prepare PocketC.H.I.P.
Make sure that PocketC.H.I.P. is turned off, then carefully remove C.H.I.P. from PocketC.H.I.P.. Flip PocketC.H.I.P. around and remove the plastic frame that surrounds the perimeter of the screen. Finally, remove the back of the case by pressing the tabs above the screen and on either side of the Home/Power button.
Note: If this is your first time using PocketC.H.I.P., you will find the docs a helpful, handy resource.
2. Disconnect the Battery
Place PocketC.H.I.P. screen-down on a non-marking surface and locate the battery connector on the left side of the board.
Grip the white plastic JST connector with needle nose pliers and gently pull away from the off-white connector that’s soldered to the board.
Warning! Pull on the plastic connectors, not on the wires!
3. Protect Exposed PocketC.H.I.P. Electronics
Cut a small length of Kapton tape and adhere it over the components on the left side of PocketC.H.I.P.. This is done to prevent electrical shorting between exposed solder pads on PocketC.H.I.P. and the amplifier.
Note: If you don’t want to buy an entire roll of Kapton tape, masking tape or electrical tape are decent replacements –at least for this application. Do not use duct tape.
4. Hot Glue the Amp to PocketC.H.I.P.
Test fit the amplifier without glue first. Orient the amplifier so that it’s near the components you just taped over, but leave some room away from PocketC.H.I.P.’s edge to provide clearance for the case to close snugly. Also make sure that the audio input pads are located closer to the PocketC.H.I.P. header pins –see the image above.
Once you’ve determined the proper placement, put a blob of hot glue on the underside of of the amplifier and press it into PocketC.H.I.P..
5. Solder Power & Ground Between PocketC.H.I.P. & the Amp
We recommend soldering wires to the side of PocketC.H.I.P.’s male header pin and below the plastic shroud. This ensures that C.H.I.P. will connect to PocketC.H.I.P. without wire obstructions.
Solder the GND pad on PocketC.H.I.P. to the – pad near the 5V pad on the amplifier.
Next, solder the VCC-5V pad on PocketC.H.I.P. to the 5V + pad on the amplifier.
Note: If you’ve never soldered before, check out this helpful soldering comic book.
6. Solder Audio Lines Between PocketC.H.I.P. & the Amp
- Solder the PocketC.H.I.P. HPL pad to the amplifier’s L pin.
- Solder the PocketC.H.I.P. HPCOM pad to the ⊥ pin.
- Solder the PocketC.H.I.P. HPR pad to the amp’s R pin.
Once that’s done, all that’s left is to solder the speaker to the amp.
7. Solder the Speaker to the Amplifier
Connect the speaker to the amplifier using two more wires. Remember you’ll need to shove all the wire inside the PocketC.H.I.P. enclosure, so don’t use more wire than you absolutely need.
Note: A trick we figured out while writing this project is that it’s much easier to glue the speaker in place before you attempt to solder to the speaker.
Solder the amplifier R- pad to the speaker terminal marked with a – and the amplifier R+ pad to the other terminal. Of course, if you want to have stereo sound, you’ll need to wire up a second speaker and attach it to the L+ and L- pads on the amp.
At this point, go ahead and reattach the front and back of the enclosure and insert C.H.I.P. into the back of PocketC.H.I.P..
8. Volume Control
Once you’ve reassembled the enclosure, power on PocketC.H.I.P. and test out your speaker by running PICO-8. You should hear 8-bit audio as soon as you load PICO-8. To adjust the volume, go to the settings menu from the home screen and move the volume slider to the desired output level.
If you want to use headphones with PocketC.H.I.P. and not have audio playback over the speaker, open the Terminal application on the homescreen. Then type in alsamixer and press enter. You’ll see a screen, like the one shown below.
Use the arrow keys and select Left Mix and press the m button on your keyboard. This will toggle the speaker off. To enable the speaker output, follow the same method you used to mute the speaker. To exit alsamixer, simply press the ESC key.
This is only the second of many PocketC.H.I.P. hardware hacks (remember PockulusC.H.I.P.). Make sure your hardware hacking plans for PocketC.H.I.P. over on the forum. We can’t wait. Happy hardware hacking!