Dec 5, 2016

DieselPunk Cellphone - Walnut Case, Powered by Adafruit Feather Fona:Final Assembly

Whew! Ready to solder the Feather Fona onto the perma proto board...

But one note, first. At some point, you may want to swap out the SIM - different carrier, dead SIM, whatever. If you want the SIM card to be removable from the Feather Fona, you need to be careful of the clearance for the SIM when the FF is soldered down. On my build, the FF is soldered at a very slight upward angle on the SIM end of the board. I can just barely pop the SIM out with a small flat-head screwdriver, then grab it with a pair of tweezers. You can just work the SIM clear of the wooden case.

Most of the soldering for the pins will be straightforward. However, there's little clearance to solder the header pins near the already-soldered OLED jumper wires. The good news is that there are only five of these.

  • Use a small soldering iron tip, if you have one
  • Use a small flat screwdriver to gently, but firmly, nudge/bend the jumper wires to the side for clearance to solder the Feather Fona pins to the board 
  • Be patient and work slowly 
  • Gently bend the wires in the other direction to solder an adjacent header
After you get the Feather Fona pin headers soldered to the perma proto, slide the Fona/perma proto combo onto the OLED pins. GND on the OLED should be at perma proto pin 5. Solder 'em up.

Now, add a battery to the FF and you have a working DieselPunk Cellphone!

Except, everything isn't in place yet...

Loose Ends
  • Attach microphone to bezel
  • Secure the LED Sequins
  • Fit the NeoPixel Jewel
  • Secure the speaker
  • Add on/off switch
  • Measure/cut/solder JST battery exetension to switch
The electret microphone is tiny, I mean, minuscule. It's difficult to handle. You'll need a pair of precision tweezers and super glue (and steady hands) to get it into the microphone bezel. Do a "dry run" first to see how to manipulate the mic into the bezel. When you're comfortable, brush a tiny amount of super glue onto the face of the microphone and quickly align it with the hole in the bezel. If you don't get it aligned perfectly, it will still work fine, just be off cosmetically.

With the mic in place, heat up your glue gun. Fit the LED Sequins, mounted on the chunk of perma proto, in the microphone bezel. Make sure the back of the mount is below the case level, so the case can be closed properly. Apply the hot glue.

Fit the NeoPixel Jewel under the speaker bezel by gently bending the wires. Aligning the two mounting holes on the Jewel in a North/South orientation (shown) makes three LEDs line up horizontally under the middle of the acrylic, backlighting nicely.

Attach the JST extension to the Feather Fona battery connector. You're going to lay the extension wires down under the speaker. You won't be able to thread it through, under the speaker, once the speaker is glued down - not enough space for the JST connector to pass through. I didn't do that, as shown in the pictures - that made the fit more difficult.

Position the speaker in the milled hole in the top as best you can. Place a piece of electrical tape over the soldered pins on the perma proto, to prevent shorts with the metal speaker case. Lay down a bead of hot glue around the outside of the speaker and hold in place until the glue sets up. Make sure the glue and speaker are below the rim of the case, so you can close the case properly. 

Measure out a length of the JST extension to reach the back cover, where the on/off switch will be set in the 12mm hole. Fit the on/off switch, unattached in the hole, with its wire leads bent 90 degrees down, flush with the wooden case.  Test fit the 1250mAh battery right above where the on/off switch sits. Cut the JST extension red leads to reach one side of the switch, with slack. Sever the black wires as well. Mount the battery with putty/tak and plug into the extension jack (connector furthest away from the Feather Fona). Test closing the case, and fix any high spots by moving things around. Cable origami...

The on/off switch is nice, good clicky action - but it has a fatal flaw. It can't take heat well. I ruined two switches: one, by soldering for too long; the other, by covering the soldered pins in heat shrink and applying the heat gun. You have been warned!

When you're happy with the layout and the case closes well enough (it will be tight), solder a red lead to each side of the switch, making sure the extension battery connector is soldered closer to the battery. Place a piece of electrical tape over the soldered leads for insulation. Take some of the slack out of the black lead and solder the black leads together, covering with heat shrink for protection. 

Test fit with the case closed again and the switch friction-fit in place. If it fits together well, glue the switch into its hole with super glue. 

The finished project will resemble this:

Now, bask in the glory of your accomplishment! You've earned it...


  1. I am building the phone project. I have it mostly sorted out and I and fitting the case, but I wonder is there any way to adjust the call volume?? Do I need an amplifier?

  2. Check the comments in the first page in this series of posts: This tutorial was so long I needed to split it up.

    You don’t need an amp. You can adjust ringer and call volume with AT commands, someone commented on that first page.