This post is long overdue. The hardware has been complete (enough) for weeks now, and the software has been improving incrementally. It is the impending arrival of the Maker Faire that finally prodded me enough to finish writing this up. I’ll be there showing this off. Here’s what the completed project (mostly) looks like: (more details after the break)
When we last left our hero, he had just finished ripping the guts out of the tele-coupler. The next obvious step was to actually use them. First, I needed to take off the (perfectly good) microphone and speaker, and connect them to the completely untested mic and speaker in the telephone handset. So, out comes the desoldering braid:
Then solder the tiny leads to the spade lugs of the handset, cover the shrink tubing, and stress relieve:
The board is mounted using foam mounting tape (2 layers), and the cord that goes to the modem is routed out the hole originally used by the phone’s main cord. The amplifier needs a 9V power source, and I didn’t have time to build a step-up (boost) converter for the 5V the arduino get from the FTDI cable, so I decided to leave the 9V connector dangling out that hole as well, and the phone needs a 9V battery to work. It’s not ideal, but it was quick. Now I just needed to get the software working, but more about that later.