The Electronic Battery Feed 31A provides power and off hook detection for a telephone talk circuit suitable for a Model Railroad dispatchers’ line.  This is one of the circuits described in the New Operations SIG Book, A Compendium of Model Railroad Operations, Chapter 9.

EBF31A:

•  Operates on 24 volts regulated DC, draws about 100 ma
•  Supports at least 4 phones off hook at once, suitable for reading and copying orders on a TT&TO railroad
•  Double-pole, double throw relay rated at 2A, with screw terminals for control of auxiliary circuits operates when off hook
  
•  Has an LED "off hook" indicator
•  Has an RJ11 jack and/or optionally screw terminals or a 2nd RJ11 for the phone line.  Standard is one RJ connector, please indicate if you want a 2nd RJ or Screw Terminals or 2 screw terminals.
  
•  Has a 2.1mm center positive jack and screw terminals for power (supplies available from Jameco, Radio Shack, Amazon)
•  Has a line level isolated monitor output on a stereo 3.5 mm audio jack
•  Snaps into the same 2.75" DIN rail that MRCS cpNodes and IOX16/32 expanders use

Click here for the Electronic Battery Feed Brochure

Click here for the Electronic Battery Feed Technical Guide and Assembly Instructions

Click here for the Application Note "The 5 Minute Phone System"

Click here for the Application Note "Hot Line Phone System"