Bi-directional intercom system

  
This is a very small telephone exchange attached only two ordinary Tele phones. Fully bi-directional facility with an intercom system. When a phone is in off hook condition , Exchange will detect it & send ringing pulse to other phone. When it will be picked up , the connection will be established between both phones. This will be taken place vice-versa.
Bi-directional intercom system - schematic

Bi-directional intercom system - img1

This is used normal step down transformer (400ma) for generating three type of deference voltages & 100 AC volt for rigging. It doesn?t provided a PCB pattern for the power supply unit. So a Vero board can be used to build the unit. Parts List : 1.Step down transformer ( 230 V to 30 V , 15 V & 100 V ) 2.Two bridged 1 A rectifiers 3.7805 ? 5V regulator 4.7812 ? 12V regulator 5.1000 uf ? 35 V 6.1000 uf ? 16 v 7.150 ma fuse & it?s holders. 8.Necessary Wires & a wire code for AC supply. This circuit is base on PIC16F84A microcontroller. Two slimier SLIC are connected to The controlling unit. It needs to identify following connections on the controlling unit circuit diagram. This is used normal step down transformer (400ma) for generating three type of deference voltages & 100 AC volt for rigging. It doesn?t provided a PCB pattern for the power supply unit. So a Vero board can be used to build the unit. Parts List : 1.Step down transformer ( 230 V to 30 V , 15 V & 100 V ) 2.Two bridged 1 A rectifiers 3.7805 ? 5V regulator 4.7812 ? 12V regulator 5.1000 uf ? 35 V 6.1000 uf ? 16 v 7.150 ma fuse & it?s holders. 8.Necessary Wires & a wire code for AC supply.



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