Iam have designed a simple door intercom using LM386 in 200 gain mode present on both the door side intercom and Inside Home intercom also KA2410 as ringer Ic at home side intercom. This system is a full duplex intercom and works on 18 volts during ringing and 9 volts for conversation. the power supply is placed inside the Home intercom which provides supply to door unit in case the visitor press the ring button and during conversation.
This System works on 4 Wires connecting the door intercom withe intercom placed inside the house.
I want to converted this on 2 wires bu maintaining the same voice quality , full duplex mode and using LM386 or some transistor based good amplifier.
Now i am working on this for last 1 year , seacrhing books and internet for schematics but never got a signal clue to design it...there are circuits which use 2 wires and LM386 but they are all Push to talk type...
Some one once replied to me that i used make a current carrier circuit but i think that are for radio signal and wireless systems so how i can use that or any other circuit to converted my 4 wires intercom to work on 2 wires....
please do mail me on this if any one has interest in my question.