In the author’s opinion the secondary light source “solution” is
more trouble than it’s worth.
However, if you don’t have night operations, and never want to
have night operations, the ambient light systemmay be the per-
fect choice. Ambient light sensor detectors will also work in hidden
staging or anywhere else that the lights are kept on constantly.
Reflective:
The third type of optical train detector is generally
referred to as a “reflective” detector. In the reflective detector
a light source is mounted between the ties aimed upward. Next
to it, and also looking upward, is a light detector.
Light is emitted from the source and, when no train is pres-
ent, the detector sees nothing. When a train is present, the
light is reflected off of the bottom of rolling stock and back into
the detector, thereby signaling the presence of a train. This
arrangement is shown in [3].
Like the ambient light system, the reflective system has no sen-
sor mounting or aiming issues and nestles between the ties
and does not interfere with scenery. Unfortunately, like the
ambient light sensor, the reflective sensor has the inter-car
dropout; which can be addressed in the same manner with a
time delay.
Optical Train Detection - 5
“Ambient light sensor detectors
will work in hidden staging or
anywhere else that the lights
are kept on constantly.”
MRH-May 2014
