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The project is designed to maintain secrecy among four parallel telephones connected to a single telephone line. When more than one phone is connected to a single telephone line, anyone can lift a phone to hear the conversation on the other one. The proposed system provides a solution for the secrecy among the telephones connected.

In order to meet this requirement we are using 4 telephones connected in parallel through a single telephone line with each telephone connected through a relay in the system. When any one of the telephone is lifted all other phones are disconnected by the relays through an arrangement of opto-couplers, the output of which is fed to a programmable microcontroller of 8051 family.

The microcontroller sends a signal to a 7 Segment display to display which telephone is lifted, while other telephones are disconnected by the respective relays with help of a Relay Driver IC interfaced to the microcontroller.

This Project can be used in houses and offices where more than one telephone is connected in parallel through a single telephone line. The project is suitable for both incoming and outgoing calls. Further the project can be enhanced by adding more number of phones with an intercom facility. An incoming caller id facility can also be added to it.

Note: The project needs 4 telephone instruments to be connected to the board for the functioning of the project. Telephone instruments are not provided with the kit.

Easy to use, Self-explanatory kit.
All-inclusive solution kit.
Extensive audio-visuals available.
Branding-free material.
Pre-programmed Microcontroller.
Call/mail for Tech Support from 10 am - 7 pm.
Can be Customized for Arduino, Raspberry Pi, PIC
Parallel Telephone Lines with Security System
Hardware Requirements
  • 8051 series Microcontroller
  • Relay Driver IC
  • Relays
  • 7 segment display
  • Opto-isolators
  • Crystal
  • LED
  • Resistors
  • Capacitors
  • Diodes
  • Transformer
  • Voltage Regulator
Software Requirements
  • Keil compiler
  • Languages: Embedded C or Assembly
Q & A
Q:  What is the Relay driver ULN 2003?
A:  ULN 2003 is a 15 pin IC used to drive a maximum of 7 relays.
Q:  Which microcontroller is used in this project?
A:  The microcontroller used in this project is a 40 pin IC from 8051 family.
Q:  What is parallel telephone with auto secrecy?
A:  At places where the telephone lines are connected in parallel, it is easier to breach into any private conversation. However this project provides a solution wherein the other telephone lines in the connection get cut off during the conversation process.
Q:  Can I implement this concept with my landline?
A:  Yes, this concept can be implemented using the landline and relevant provision is provided on the PCB.
Average Rating
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Showing 4 of 4 reviews
DINESH WANKHEDE, Aurangabad on 24th July, 2015, 11:24 AM

I come to know about Edgefx while searching for the project. I used Major projects as a keyword in Google to find Edgefx.I decided along with the project I am getting the Report and Presentation slides.Yes delivered on time with all components.No I directly purchased the project through online.No Suggestions required.

DINESH WANKHEDE, Aurangabad on 23rd July, 2015, 11:44 AM

I come to know about Edgefx through Internet. I used the keyword ECE Readymade kit in Google to find Edgefx.I decided to buy a kit from Edgefx because it looks simple and easy to understand. I like the readymade kit provided by Edgefx.Yes the kit delivered on time with the right components.I directly purchased the project through online.New Innovative projects should be added.

Ajith Thampi, Ernakulam on 5th August, 2014, 11:44 AM

I decided to buy a kit from Edgefx by seeing the 100% output guarantee.I like the complete kit.

vemalarao, hydrabad on 13th May, 2014, 01:40 PM

am impressed hugely with the project I purchased. I bought DIY ,Iliked the PCB, audio-visuals and everything about the kit. The kit is perfect for students.

Rating Breakdown (4 Reviews)

Edgefx Technologies Pvt. Ltd.,
Plot No. 105, 3rd Floor,
Liberty Plaza, Himayathnagar,
Hyderabad - 500029,
Telangana, India
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