Infrared ('IR') Train Detectors

• Coded pulsed infrared proximity sensors for detecting model trains on the track.
  • Pulsing (modulation) allows the detector to ignore ambient lighting.
  • Coded pulsing allows each detector to ignore the IR signals of other nearby detectors.
• May be used as a reflective detector (sensors in the roadbed) or as an interrupt detector (detector looks across the track).
• Sensors can be used with the room lights on or off, they do not require overhead light sources.
• No rail gaps required, no modifications to rolling stock.
• On-board LEDs to aid with installation.
• Relay contact triggers crossing signals, trackside signals, panel lights or action accessories.
• Automatically switch track power, see the how to automatically stop trains and the collision avoidance at track crossings pages.
• Infrared detectors also available as an Arduino shield.

MRD1 - Single & Simple

• Single position detector, senses a train at one point on the track.
• Includes optical sensors with 2-ft. wire leads.
• When activated, the on-board relay contact closes. You connect your circuit to this relay contact, it functions as an on/off switch for your circuit.
• Output contact rated for 3 amps.
• To control higher currents, use with an auxiliary power relay
• Compact size: 1.7 x 1.5 x 0.7 in.
• Power required: 8 to 16 volts AC or DC, 40 milliamps.

The MRD1 is available in two versions, MRD1-V and MRD1-NV, described below:
 

MRD1-V variable delay version

Using the on-board delay control, you select one of two operating modes:

Turn the delay control counter-clockwise from center to put the MRD1-V in one-shot mode.
 
In one-shot mode the arrival of a train activates the detector, closing the relay contact. An internal timer immediately starts ticking, and when it reaches its limit it de-activates the detector, opening the relay contact.
 
The detector always activates for the same length of time, whether the train is still on the sensor or not.
 
You set the activation duration with the delay control. Turn it fully counter clockwise for the minimum 1/3 second 'on' time. Turn it back toward center for longer 'on' time, up to 14 seconds.

Turn the delay control clockwise from center to put the MRD1-V in continuous mode.
 
In continuous mode the arrival of a train activates the detector, closing the relay contact. As long as the train is on the sensor, the relay contact stays closed ('on').
 
After the train clears the sensor the detector stays active for a short time, called a 'drop-out delay.' After the drop-out delay has elapsed, then the relay contact opens (turns 'off').
 
You set the drop-out delay time with the delay control. Turn it fully clockwise to select the minimum 1/3 second drop-out delay. Turn it back toward center to select a longer drop-out delay, up to 14 seconds.             

MRD1-NV non-variable (fixed) delay version

Single detector, as above, that always operates in continuous mode with a 'drop-out' delay fixed at one second.

                                  MRD1-V-AD variable delay that activates After Departure

Single detector, as above, that activates an accessory after the end of the train clears the IR sensor.                            

Activation 'After Departure'
 
Need to activate a layout accessory after a train departs from a particular location?
The MRD1-V-AD version will do this for you.
 
You adjust how long the circuit waits before turning on the accessory, from 1/2 to 20 seconds after the end of the train leaves the sensor.
You select whether the accessory is energized momentarily (1/2 second) or continuously.                               

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