Telephone Handset Connector Replacements
I have some old telephone handsets, where at least one of them seems to date back to the 1930's based on some patents ("British Patents 319837.328926.433234") that I found. All of them had strange connectors incompatible with modern equipment:
![Old connection on handset #1](images/handset_1_old_connector.jpg)
![Old connection on handset #2](images/handset_2_old_connector.jpg)
![Old connection on handset #3](images/handset_3_old_connector.jpg)
But since the speaker and microphone technology has remained mostly the same for over a century, I decided to simply replace the connectors with modern mini jack plugs:
![Mini jack plug replacements](images/handset_jack_replacements.jpg)
This makes it possible to connect them easily to a modern PC and even use them for voice chat.
On the first one the original cable disintegrated when I tried to re-use it, so I replaced the entire cable. This one also has a switch that I wired to pin 8 and 7 on a DE9 connector, so that I can use the CTS/RTS trick to read it through a standard PC serial port.
![Handset #1 finished](images/handset_1_finished.jpg)
On the second one I was able to re-use the original cable. This one also has a switch, but I did not wire that up to anything.
![Handset #2 finished](images/handset_2_finished.jpg)
On the third one I had issues with a broken wire in the original cable, so that had to be replaced as well. Here I ended up simply re-using the entire cable with connectors from a broken PC headset.
![Handset #3 finished](images/handset_3_finished.jpg)