Sensor Signal
(or track sensor)
•Automatic Train Control for multiple trains (DCC or DC)
On the real railway train drivers have to drive to signals and stop at red and although that is also
nice to do on model railways, most people operate their layouts by themselves and have too much
to do driving trains, changing points and standing back and enjoy it!
Train-Tech’s Sensor Signals (or the SC100 Signal controller for automating existing signals or N
gauge etc) are Automatic and work just like the real railway’s Block Section signalling, normally
showing green but changing to red as soon as a train goes past it and staying red until the train
clears the following signal after the next section. However a red signal cannot stop the train on its
own, but by making an isolated track section just before the Sensor signal and linking the signal to a
Relay Controller to control the track section, trains approaching a red signal will stop until the signal
displays green and makes it safe for the model train to proceed into the next section. In this way you
can have a completely automatic model railway with several trains ‘chasing’ each other but never
colliding as they will be held at least a section away by Sensor Signals working with Relays.
Although this sounds complex, it is actually relatively easy to wire thanks to the technology already
in the Sensor signals and Layout Link, which is a single wire control system which links the signals
and relays together. The illustration below shows how to wire two Sensor Signals and two stop
sections to an RL1 to stop trains when they come up against a red signal. This shows just two stop
sections, but it can be scaled to many more in the same way, either end to end or continuous ovals.
6
Direction
of Train
To cut the rails use a Dremel type saw, track cutters or use isolating tracks.
You can use plastic isolating fishplates to join cut rails neatly and smoothly.
Stop Section
Rails are cut to make an Isolated track section before
each signal which is long enough to take the longest
locomotive and so stop it before the signal if it is red
S M LEARN DCC/DC S M
NO COM NC NO COM NC
Sensor Signal
(or track sensor)
to other signalsother signals
The Sensor Signals are all powered and linked together as normal (explained in signal instructions)
and a single wire from each Signal goes to the S input of the Relay Controller. A Relay Controller
has two relays, so each can control two track sections and each isolated track section is connected
to the Normally Closed (NC) relay output so that when the relay is not activated by the signal (ie
when signal is red) it connects power to the track section as normal. You can use this system on
either analogue DC or DCC track power layouts, but note that the loco’s will come to a sudden stop
once they are are fully inside an isolated track section unless they are DCC-ABC decoder fitted
locos and optional ABC diode modules are fitted as shown – see page 7 for more on ABC braking.
Manual override
Trains can be released manually from the stop section using either Mimic switches connected to the
‘M’ input of the RL1 (page 4) or DCC commands to override the RL1 (page 3) or Sensor Signal.
Semaphores Although not strictly prototypical to the real railway, it is possible to control Dapol
Semaphore signals using Track Sensors with Train-Tech SC300/400 modules and to stop trains in a
similar way to the colour light signals by also connecting the Track Sensor output to RL1 as above.
Optional ABC
Diode Module
Interference suppression
Note that you should include
appropriate suppression
particularly for trains, motors
and solenoids using
capacitors and chokes to
prevent interference
Optional ABC
Diode Module
POWER
Power the Sensor Signal or Track
Sensor and the Relay Controller
from the same power supply;
either Track DCC or connect it to
12—16V maximum smooth DC.
See bottom of page 2 for power
connections to Sensor Signals etc
