Phonos: a voice input device. Part 1: The Build

The other day while organizing some phones, it dawned on me that wall phones belong on the wall, so I started hanging phones on the wall. After hanging four phones, I came upon a wooden framed rotary that spoke to me.

All devices eventually speak, and they always say the same thing. Sometimes their words are a deafening roar, and sometimes they whisper ever so softly, but their message never changes. Take me apart!

Who am I to ignore such a plea? :)

After the phone was opened up, it was time to put it back together again, and I opted for a few 'upgrades'. Specifically, I wanted to put a CHIP computer in the phone and make it do stuff.

say hello to Phonos

Just a peek

Hot diggity! would ya look at that! All of those sweet switches and flipple-zootles have plenty of good wire connected to them, and there is room enough for a cluster of CHIPs.

The switch for the receiver cradle was certainly not the massive mechanical monstrosity I was expecting. Testing resistance across the switch's wires told me which wires I might want to use later.

Replace the microphone

The standard microphone in phones of this era have never worked well for me when it comes to wiring for alternative uses. After a little solder and hot glue, a 'puppy chewed' microphone replaced the original.

A bit more soldering

Much like electrical tape, the sleeves of these RCA jacks do a wonderful job of hiding my sloppy solder skills. :)

Hack some hardware

To the right of the U.S. Dime, there are 3 rather small square pads on the CHIP. The CHIP has a 1/8" jack for supplying Audio and Video Out. As a nifty bit of design, the CHIP can be hacked to convert the Video Out to Microphone In.


The area between the top and middle pads was scraped clear with a fine blade... ha, who am I kidding, I hacked that board like a barbarian vanquishing a foe.

Finally, a sweat inducing tiny blob of solder closed the circuit between the middle and bottom pads.

Wooooweeee, what a rush.

Test the work

With the soldering iron still hot, RCA connectors were added to a microphone and a speaker, and the whole shebang was slapped together for a test.

Fortunately, it all worked. Honestly, I was quite surprised and relieved. That sort of fine soldering is certainly at the limit of my soldering skills.

Final set up

A pair of leads were soldered to the wires of the cradle switch, and then the soldering iron was retired for the evening. Doing so freed up an electrical outlet for the hot glue gun that fastened the CHIP's guard plate to the inside of the phone case.

The leads from the cradle switch were connected to GPIO7 and Ground.

Hanging on the wall

Like all wall mount phones, Phonos belongs on a wall. :)


If someone had spent the evening writing code instead of writing about building an input device, Phonos would be fully operational. But ya know, stopping to write about something isn't actually "stopping". Documenting a creation is a creation in itself. Anyway, there are a few bits of code that need to be hacked together before Phonos is finished and then I'll be back with some words about software.


P.S. Phonos is running Debian 8 with a 4.4 kernel, and blather to handle voice input.