and an interrupter optical detection system can function satis-
factorily on a model railroad.
Ambient light:
A second type of optical detection system I’ll
call the ambient light sensor. In this system a light detector is
placed between two ties and is facing upwards. The light detec-
tor is kept on by ambient room light. When a train passes over
it and cuts off the ambient light, the train is detected. This
arrangement is illustrated in [2].
Other than a small hole between two ties at intervals down the
track, there is nothing to interfere with your scenery. The ambient
light sensor does suffer from the inter-car drop out limitation; but
that can be addressed with an electronic or software time delay.
3
3. The Reflective Optical Train Detector.
Optical Train Detection - 4
MRH-May 2014
