Tam Valley Depot QuadLN

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Summary: The QuadLN is an accessory decoder/servo driver for LocoNet from the Tam Valley Depot.


From the manual:

The Quad-LN is an accessory decoder that can drive 4 servos for controlling turnouts. The servos can be actuated using pushbutton or toggle switch inputs. A single input can control one or multiple servos. The Quad-LN can also drive 4 remote relay boards.

LocoNet and JMRI are required to operate this device.


  • Display the servo state on a Tam Valley Depot Fascia Controller or drive user control panel LEDs.
  • Besides showing whether a turnout is Closed or Thrown, the Quad-LN can indicate when a servo is in motion (without requiring Turnout Position Feedback sensors!) and when it is Locked.
  • Loconet device. Servos can be controlled via Loconet Switch commands. Turnout position can be reported to software such as JMRI. The Quad-LN even provides local control Locking
  • capability so that local pushbutton or toggle switch servo control can be disabled on an individual servo basis whenever desired by just sending a Loconet Switch command.
  • Inputs can be wired to turnout position sensors to generate LocoNet Turnout Feedback messages. Inputs can also be wired to detectors and then report block occupancy using Loconet
  • General Sensor messages. Almost any device with a contact closure or logic-level signal output can be wired to an available Quad-LN input and then reported via Loconet.
  • Cascade and programmable Routes/ Selectors features that take advantage of the Loconet to implement layout control functions such as yard ladder control and track selection.
  • Using the Quad-LN template in JMRI greatly simplifies things.


A 5 digit extended address is used for the Device Address. This avoids conflict with locomotives and other devices when doing Ops Mode programming.

The Default Address is 11000. Accessory Decoders support up to 16382 ($3FFF) unique addresses.


Signal Board for Expansion Port

  • Drive up to 24 LEDs
  • Supports
    • Common Cathode
    • Common Anode
    • Two lead Bi-colour LED
  • Series Resistor installed, provisions for an additional resistor are provided.
Signalling Support
  • Fade
  • Searchlight transition effects
  • CPL semaphore effect
  • Flashing signal aspects
  • Flashing grade crossing with cross fade.
  • Up to 48 signal aspects can be configured
  • Signal control via NMRA Signal Head/Mast messages or Turnout Controlled Mast messages

Detector Add On Board

  • Adds 4 detection blocks to the Quad-LN.
    • Current based using transformers (CTs).
  • The detection transformers are mounted on a small PC board with a screw block
  • Sensitivity can be adjusted using the QuadLN_S remote aligner
  • A fascia controller can be used

Fascia Controller

The Fascia Controller provides easy control of turnouts. A number of options are available.

Further Reading

External Sites

Tam Valley Depot makes a number of DCC accessory boards, boosters and the Frog Juicer.