1A DCC occupancy detector by current consumption


In DCC, the LEC000042 occupancy detector allows to detect the occupancy of a track section and to trigger many automatisms or systems.
  • Detects all trains in the 2 directions.
  • Threshold of detection highly sensitive and adjustable.
  • Double changeover relay to connect any system.
  • Delay on deactivation for avoid inadvertent reactivations.
  • Possibility to force the activation of the relay via a dedicated terminal block.
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… mais vous pouvez trouver les fichiers sources de ce produit sur GitHub.

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Ce produit est open source

Ce produit est open source, vous pouvez donc trouver tous les fichiers nécessaires à sa fabrication sur GitHub.
Il n'est pas nécessaire d'être un as de l'électronique pour faire refabriquer ce produit, un tutoriel vidéo vous montre comment faire.


This module is an occupancy detector by current consumption.
The adjustable sensitivity of the module will allow you to detect without any worries your locomotives, cars with lighting, or all graphitized axles of your railway vehicle.
When the module detects the presence of railway vehicles in the detection zone, it immediately activates a relay with 2 changeover contacts.
The relay's contacts present on the module allow a very generic use. Some cases of use are listed below.

  • Block system.
  • Triggering a sound effect.
  • Hidden station management.
  • Automatisms (level crossing, …).
  • Signage management.


This module is digital (DCC) and analog compatible.

Connections and behaviors may differ when the module is used in analog, for more information, see the dedicated listing.
Note : Several versions exist. To help you choose, you will find a comparison table below.

Installation and wiring of the module

The wiring of this module is very simple. As shown in the basic diagram below, with only 3 wires, the module is functional.

For a quick and easy installation:
  1. Isolate one of the rails of your detection area.
  2. Connect the power rails, or directly from the DCC control unit to the green terminal block (terminals A and B).
  3. Connect the insulated rail on one of the 2 terminals “B DETECT”.
  4. Test and enjoy of all the possibilities offered by the detector's changeover contacts.
  5. Attach the module with screws or hot glue.
Click on the image to open it in full size

[facultatif] Forcing the activation of the relay.

Some systems, such as station stop management, may require the need to force relay activation.

To do this, simply connect the two terminals "FORCE" by a switch, as shown on the attached diagram.

[facultatif] Adjusting the sensitivity of the detection.

The module arrives pre-set on a standard detection sensitivity which should allow to detect any locomotive, even at standstill (detection of the consumption of the machine decoder). If you are not satisfied with the detection level, you can adjust it as shown in the diagram opposite.

To decrease the sensitivity, turn the potentiometer clockwise.

To increase the sensitivity, turn the potentiometer counter-clockwise.

Note : The potentiometer is very fragile. Never force it to deteriorate or make the module inoperable.

Examples of use

Connection of a two-tone light

This diagram shows how to wire a two-color light so that it changes automatically depending on the presence of a train in the detection zone.
Click on the image to open it in full size

Section protection with automatic stop

This simple assembly makes it possible to protect a section of track (the detection zone): if there is no train in the detection zone, the relay of the detector shunts the 2 terminals of the stop module, so a train can pass without problem. As soon as a train is in the detection zone, the braking module orders the arriving trains to stop in the stop zone.

Use cases :protection of a hidden track section (loss of cars, …).

Note : Not all decoders are compatible with the ABC technology used by the DCC braking modules. For more information, consult the breaking module listing.
Click on the image to open it in full size

Automatic sound triggering

This diagram shows how to interconnect the presence detector with the LEC008011 sound module. This setup can be used to trigger a sound automatically (e.g.: a horn at the entrance of a tunnel, …)
Click on the image to open it in full size

Simple block system

This diagram shows how to make successive block systems by chaining the figure entitled "Section protection with automatic stop". Please note that the block system is only effective in one direction; a train arriving in the opposite direction will be able to pass normally.
Click on the image to open it in full size

Addition of a two-tone light in a block-type installation.

This diagram shows how the second changeover contact of the occupancy detector relay can be used to connect a two-colour light to it and thus create a block with automatic light changeover.
Click on the image to open it in full size

Manage a switch in a detection zone.

These diagrams show how a switch can be integrated into a detection zone.

To do this, it is necessary to have a changeover contact that changes at the same time as the switch position (contactors available on the motor directly, on a relay, or on the control button).
Click on the image to open it in full size
Click on the image to open it in full size

Complete block system with rolling area

This diagram shows how to create a complete block system with the DCC occupancy detector and the LEC001020 breaking module.
Click on the image to open it in full size

Chain of block systems without rolling area.

This diagram shows how a complete block system can be created with the occupancy detector. Please note that for optimal operation, the stop zones must be the same length; it is therefore strongly recommended to choose the following scheme, which includes rolling zones, thus making it easier to have the same length of stopping zone everywhere.
Click on the image to open it in full size

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Weight0,025 g

1 module


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