PiTelephone, an ancient fully functional phone created from a Raspberry Pi
We are weekend and, undoubtedly, there is nothing better than a good daring project that have a good time, especially if in the end we got so amazing phone things like create a fully functional disk as you see on these lines. The project has been christened PiTelephone and is nothing more than an old phone connected to a Raspberry Pi which it is what "makes all the magic".
If you want to recreate as much as possible the result you can see right video at the end of this same entry, let you know that its creators chose the GPO phone model 746 from 1970, specifically we are talking about an English model. To make the phone ring is required connecting the two sides of the coil to a source of 16 volts while to give power to the Raspberry Pi it requires a converter, specifically the model used is an OKI-78SR.
The photo you have on these lines necessary for the system to achieve the typical frequency of telephone exchanges of the time that, in the UK and by those then it was 25 herzios, for this two relays were used SPDT, one for current and one for oscillate between the two coils. To count the pulses were supported in the library raspberry-sharp-io and a simple script in C # which counts the time in milliseconds between pulses, so it knows what number was dialed. You have all the code on GitHub.
We reached the end point where, thanks to technologies like FreeSWITCH, a cross-platform solution designed to connect the most popular communication protocols using voice, audio, image or other multimedia resource, PJSIP, a library of open source for multimedia communications and Skype SDK. I leave you with the video mentioned.
Source | HW libre
Autor: Juan Luis Arboledas