The Dispatcher/Operator Telephone board provides all of the electronics and connection points to make a Dispatcher or Operator’s station for a model railroad layout communication system. It provides independent control of receive, transmit and “break-in” volume and since it provides its own power, it will not load the telephone line in large systems. The DS/OP board can help telephone systems suffering from “can’t hear” complaints.  This is one of the circuits described in the Operations SIG Book, A Compendium of Model Railroad Operations, Chapter 9.

Features

• Independent receive, and transmit volume controls to ensure the DS/OP can hear and be heard
• “break-in” (when a station is trying to talk to the DS/OP while the DS/OP is talking) volume and output phase adjustments to control feedback when used with a desk mic (you must use a directional or cardioid pattern mic and a foot switch for reliable mic/speaker operation)
• Does not draw power from the Dispatcher’s “Train Wire”
• Supports “computer” headsets with separate 1/8” (3.5mm) plugs, or free standing microphone/speaker arrangements, including “candlestick” or “scissor” style telephones modified for dynamic or electret mics
• Compatible with tip/ring/sleeve or tip/sleeve plugs on audio inputs and outputs
• Supports dynamic and electret microphones with built in electret power supply (for computer headsets)
• Push (stomp)-to-talk voice switching with screw terminals for foot switch
  
• 2 RJ11 jacks for connection to Dispatcher’s train line as well as screw terminals
• Uses Regulated 24VDC @ 15 mA on 2.5mm barrel jack, screw terminals, or on pair 3 of the RJ11 (can share a power supply with our EBF31A Battery Feed board)
• Hybrid Null adjustment to reduce line noise
• form factor is 7 cm x 16 cm (2.75" x 6.5") so it fits in our DINRail next to an EBF31A

Data Sheet

Schematic and Board Layout

Gerber Files

Assembly and Installation Instructions