Experiments Included:

  • DTMF Trainer
  • 3 X Tone / Pulse DTMF Telephone Sets
  • Ring Detection Phenomena
  • Trunk Relay Switching
  • Switching Mechanism of Relay
  • OFF Hook Detection
  • Working of the Flash and its use
  • Amplified Receiver Signal
  • Switching Mechanism of Relay
  • Ring Enable Signal
  • DTMF Receiver
  • Dialing of DTMF Digits
  • Frequency for Ring Generation
  • Ring Back Tone
  • Dial Tone and Busy Tone
  • Self Generated Ringing Signal
  • Frequency of Ringing Signal

Telephone exchange is serving mankind for decades. It is one of the best combinations of Analog, Digital & Mechanical circuits. The EPABX has undergone many phase of changes ever since its existence. EPABX trainer forms the basis of Analog telephone exchanges. Automatic switching can be performed and studied using real time waveforms. The functional blocks provides easy understanding of the working of the system. Visualizations of the switching and detections are explained with the help of software. A DTMF Telephone Trainer is also provided for better understanding of Telephony signals.


  • Required Circuits Tested
  • Each Section Clearly Marked for Input and Output
  • Polarity Protection
  • Monolithic Switching Matrix
  • Monolithic DTMF Decoder
  • Monolithic Dialer, Ringer
  • Each Section Clearly Marked for Easy Understanding

Technical Features:

  • Inputs: 6 Trunk / Direct Lines
  • Extension: 16 Lines
  • Switching: Cross Point Space Division (Microcontroller based)
  • Standard Features: Dial Tone, Busy Tone, Ringer, Ring Back Tone, Music on Hold
  • Dialing: DTMF and Pulse
  • Loop Resistance: Extension -600 Ohms, Co-line- 1200 ohms.
  • Cross Talk Attenuation: >70 dBm.
  • Configurable Features: Direct Access to trunk line, Redial, Line Status Indication, Call Transfer, Call Pick Up, Direct Access Trunk, Call Forwarding, Call Conference, Hot line System etc
  • Interconnections: 2 mm safety pins

Accessories: Power cord, Experiment Manual, Software CD and 2mm patch cords, DTMF Trainer IT-4401, 3 x telephone sets