Distribution of a Digital Telephone Set Diploma in Telecommunication Engineering

  • Introduction: Telephone exchange lines connecting the power supply 40 V.D.C to 60 V.D.C are set for each Telephone. This Voltage to Operate the Telephone. When the handset to the base unit is installed, then the DC voltage is applied to the ringer section. Digital telephone system mainly build consists of the following components: (i) In-Line Protector Section (ii) Ringer Section (iii) Voltage Dropper Section (iv) Sound or Speech Section (v) Keyboard or Matrix Section and (vi) Dialer Section


  • In-Line Protector Section: It comes with two sets of exchange line Telephone. It is associated with the exchange of any two telephone sets are used for audio signal transmission and Reception.
    DC voltage electronic devices to operate the structurally. The circuit is made of a protector, which will supply voltage circuit Basic structurally. A bridge rectifier circuit is used as the protector circuit. It provides positive polarity output for any input structurally. Ringer through the polarity of the output circuit is protector. Coming from the exchanges between the two by adding the line voltage stabilization is a VDR.


  • Ringer Section: This Section Process 20Hz Signal from Telephone line and build ring signal for provide to buzzer. All the processing system of ringer section controlled by a IC (Intergraded Circuit). A Single Capacitor and on-hook/off-hook/Ringer Switch provide in Ringer Switch. Capacitor helps to Stop DC Current and help to g AC Current. When a call comes from Telephone, Then the Exchange Carried 2o Hz Ringer Signal to the Set.


  • Voltage Dropper Section: 40V D.C to 60V D.C Source comes in Set from Exchange by Telephone Line. But the Electronics Device of Set only can work in 9V to 12V. For this, here use a Voltage Dropper Section to Change the voltage from 40V-60V, to 9V-12V. This Section is built by Zeenar Diode and a Transistor.


  • Sound/Speech Section: This Section Process the AF Signal and Audio Signal build from Microphone. This entire Signal Comes from Exchange. This section is controlled by a single IC. When the Handset Pick up from Telephone, Then Work the sound section.


  • Keyboard/Matrix Section: All the Puss Bottom of Keyboard Design by Matrix. There are 12 Key Available in 4 Rows and 3 Columns. The Puss Bottom are- 0,1,2,3,4,5,6,7,8,9,# and *


  • Dialer Section: The Work of Dialer Section is making Dial Tone for Speaker, Build Pulse or Frequency to send Exchange for make call. Any Telephone Set Work one of the Following Rule of Providing two Rules. The Modes are Tone and DTMF (Dual Tone Multi Frequency)


  • Conclusion: A Digital Telephone set work with the previous process. Here we wrote details for learn you more and save your valuable times.