This video will describe how to build an intercom using old telephone sets. A battery, resistor and a wall phone jack is all that is needed.
Parts needed:
9 volt battery
330 ohm 1/2 watt resistor
Battery clip and cable
Dual phone jack plate
Plastic electrical box
* Note
A higher voltage battery can be used
together with a higher value resistor.
![](https://s2.save4k.ru/pic/FpWxkC72uJM/maxresdefault.jpg)