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Intercom circuit diagrams

High Quality Intercom
High Quality Intercom
December 25, 2010

A very high quality intercom, which may also be used for room monitoring. [more]

Intercommunication (Intercom)
Intercommunication (Intercom)
December 8, 2010

This is a great intercom circuit that can be used in many ways. It uses 22V to operate and maybe it will work at a lower voltage (you can try it). For input/output it uses... [more]

The Original 2 Phone Link Design
The Original 2 Phone Link Design
July 2, 2010

This is the circuit that sparked off all the other Link Telephone Intercom designs. Originally designed back in 1996 with heavy duty relays and their contact banks, it was updated late last year with the... [more]

The Link Telephone Intercom – Every Home Should Have One
The Link Telephone Intercom – Every Home Should Have One
July 2, 2010

The Link circuitry is simple and efficient, employing just two ICs, half a dozen transistors, and a handful of garden variety components. It all runs on 12 volts and is easily assembled. You can have... [more]

The Link A2B+1 (the Link Telephone Intercom - DTMF version)
The Link A2B+1 (the Link Telephone Intercom - DTMF version)
July 2, 2010

the Link Telephone Intercom - DTMF version [more]

The Link 4+0 – Internal Intercom
The Link 4+0 – Internal Intercom
July 2, 2010

This version of the Link is for those who really need a good cheap intercom that will work reliably, but without access to an outside Telco line. This could be in a pre school, a... [more]

The Link "P" - Privacy Link! (Telephone Intercom)
The Link "P" - Privacy Link! (Telephone Intercom)
July 2, 2010

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... [more]

8 Line Intercommunication using 89c51
8 Line Intercommunication using 89c51
June 22, 2010

This project is aimed to make the low cost intercom system by which eight telephone lines can be interfaced with this hardware. [more]

Baby Watch Out
Baby Watch Out
April 25, 2010

It's a very simple circuit, for the follow-up of baby. It can however be also used for other use, as intercom etc. In the place of M1 we can we use a simple electret mic... [more]