Yes folks, it’s time for another horse to bolt from the Downunder stable of telephone intercoms (unfortunately before the gate could be shut on it…) and other zany electronics type ideas. The circuit you are about to see is the culmination of some effort at improving the basic Link intercom design. You may think that pulse dialing is ‘old hat’ nowadays, but the exercise of building and testing the Link ‘P’ in this format, and understanding how it all works, is well worth the effort. Not to mention all those out there who have the old style rotary dial phones as collectables – you can now make them work for you, or display them actually working with confidence.
The Link “P” – Privacy Link! (Telephone Intercom) - [Link]