Help Needed On 2-way Intercom Design

[DjCombo]

Hi guys!
I'd like to get some info about a 2 way intercom design?
I got myself some Schematic on the net but I'd like to have a basic block diagram of an intercom as a backup of understanding?
Please help
Thanx!

 

[crutschow]

Is this to be wired or wireless?

 

[audioguru]

You forgot to attach the schematic of the intercom circuit so I am guessing about it:
An intercom is two microphones, one or two mic preamps, one power amp, two speakers and a switch. Sometimes the speakers are used as microphones.

 

[DjCombo]

Sorry Guys!
Here is the schematic that I prefered best!
The intercom a wired one!
What I need is a general representation of a 2 way intercom in block diagram
and perhaps some explanations of the schematic.
Thanx 4 the reply!

 

[audioguru]

It is obvious that the simple intercom has two identical sections and two identical power supplies.
Each section has an electret microphone, a preamplifier, a power amplifier and a speaker.

Press-To-Talk pushbuttons activate a relay that switches the communication direction.

 

[DjCombo]

Thanx for the reply!
Could you please refer me to a book or a website about intercom design?

 

[audioguru]

There is no such thing as "intercom design".
You need to learn about how transistors work so you can design a simple microphone preamp circuit.
You need to learn about microphones, power amplifier ICs and speakers.

 

[DjCombo]

All right I get it!
I think I should find out more about microphone preamp circuits and speakers.
I have already been introduced to transisotrs and power amplifiers.
One more question.
What circuit should I incorporate in order to build a 2 way wireless intercom?
Thanks for the help!

 

[audioguru]

What circuit should I incorporate in order to build a 2 way wireless intercom?

A wireless intercom does not have wires connecting the two stations together. Radio signals are used instead of wires. A radio transmitter and radio receiver are complicated circuits. In some countries certified radio transmitters and frequencies are needed or licences.

In Canada and in the US we can buy inexpensive FRS and GMRS "walkie-talkies for adults" that work very well and have a far range. It would be too complicated to make them yourself.

 

[saturn19]

I need the circuit diagram of a two way intercom (not wireless) with its working and component specification.cud u give it?

 

[audioguru]

A simple intercom is half-duplex. You must press a button while you speak which cuts off sounds from the other end.
A much better intercom is full-duplex. Then you and the other end can talk and listen at the same time.

A full duplex intercom project is at www.redcircuits.com .
It is also at Electronics Lab - Home . The full-duplex intercom uses a shielded audio cable to connect them together: