2 Line Intercom Cum Telephone Line Changeover Circuit:

2 Line Intercom With Telephone Line Changeover Circuit: The circuit presented here can be used for connecting two telephones in parallel and also as a2-line intercom. 

Creating your Own Telephone Ne2 Rk: you can easily create your own intercom system using two telephones, a 9-volt battery (or some other simple power supply) and a300-ohm resistor  

Door Phone Intercom:

Doorphone Intercom:

Head set Intercom :

High Quality Intercom:

IFB Intercom :

Intercom Preamp: a convenient way of making an intercom is to use a loudspeaker as a microph1- 

Intercom:

Low Cost Transistorised Intercom:

Old Phones As An Intercom:

Old Telephones As Intercom:

Party line Intercom :

Remote Control using Telephone: Here is a tele-remote circuit which enables switching "on" and "off" of appliances through Telephone lines. The circuit described here can be used to switch up to nine appliances (corresponding to the digits1 through 9 of DTMF the Telephone key-pad). The Telephone can be used to switch on or switch off the appliances also while being used for normal conversation. FAIR WARNING -- THIS SITE HAS ANNOYING POP UP ADS.

Two Line Intercom Cum Telephone Line Changeover Circuit:

Two Line Intercom With Telephone Line Changeover Circuit: The circuit presented here can be used for connecting two telephones in parallel and also as a2-line intercom.

Using the Comrex Hotline or Vector on a Dry Pair: how to use simple pair of wires with no voltage, ringing signals to interconnect normal Telephone line devices