Cheap Intercom System Interface

Hi there, today i like to tell you a little thing about what i have extract from the internet lately. I always wanted to make an intercom system to make people easier to tell who they are before entering my home, so here in is!, I just found out a new solution on making the cheapest ever intercom. Hope that making this intercom will not burden you.



This circuit comprises a 3-stage resistor-capacitor coupled amplifier. when push button S2 is pressed, the amplifier circuit formed around transistors T1 and T2 gets converted into asymmetrical astable multivibrator generating ring signals. These rings signal are amplified by transistor T3 to drive the speaker of earpiece.

This circuit only consume 10 to 15 mA only, so I have no worry about it because I use a 9-volt battery for temporary and after a month later, I replaced those batteries with a 3-pin multi-voltage adapter.

Edited with Adobe PhotoShop CS3

To make a two way intercom, u need two identical unit . Thus of course PC B1 speaker will jump to PC B2 unit and PC B2 speaker will go the other way. Just like I have highlighted in the picture.


That is a little bit from me! Just hope you like it. Coming up soon might be more interesting to you. signing off from Mohamad Fairulnizam