3
Train
Sensor
Avoid bright light or the sun
shining directly at sensor
• Using a sensor signal on its own
As soon as the power is switched on your signal should light green. If it does not light at all check
the power connections thoroughly - see previous page.
To test push a wagon or coach past the signal. The sensor should detect it and the signal should
change from green to red (or to yellow on a distant signal).
Several seconds after the train has passed the signal it will change back to green (via yellow if it is
a home-distant type signal). Note that the signal will only change back to green after it has not
seen any train over it for several seconds, so if you have a long train it will stay at danger for as
long as a train is moving over it. A signal used on its own can only ever work in this way because it
does not know how far ahead the train is, but if multiple Sensor Signals are linked together the first
signal will stay at danger until a train has cleared the following block and so on through the block
sections protected by other sensor signals - see page 4.
The sensor uses infrared and is quite tolerant
of varied lighting conditions, but for reliable
operation avoid strong lights (such as the sun,
bright or flickering lights) or shadows directly
onto the sensor.
The sensor should detect most locomotives
and rolling stock, but if a particularly tall or
dark train passes undetected a small label or
dab of white paint underneath will help reflect
the infrared more consistently.
• Manual override of a single Sensor Signal
Although Sensor Signals will work completely autonomously, you can manually override them to
force a signal to stop/caution using either a Mimic Switch or a DCC command. On the real railway
these are called semi-automatic signals and exist so that a central signal box can stop trains in
the event of an emergency like a tree which has fallen on the line or for other operational reasons.
A Mimic Switch
is an easy way to override a Sensor Signal and also offers other benefits such as
an LED showing the colour of the signal and another LED which lights when the train passes the
signal, as well as controlling a route indicator etc. Wiring is simple too with just one wire from the
signal to the mimic switch and it works on both DC and DCC layouts. (details on a following page)
Mimic
Switch
A Mimic switch
connects to a
Sensor Signal using
just one wire and
allows manual
override of the
signal as well as
LEDs which show
signal state and
train detection, etc
DCC override
If you are using the Sensor Signal on a DCC layout you can override the signal to stop/caution
using a single command to an address you set up using One-Touch DCC - see page 6. (Make
sure that you choose an address not used on anything else on your layout!)
Signal colour LED
Train detect LED
