Below is a picture of one of the Search light signals with a road deviation feather. It has three aspects,
Red, Yellow and Green. Signal power is 12 volt DC supplied from a 12V 7.1 Ahr Battery.
Control is via a wireless modem. The communications protocol is simple ASCII command strings.
The CPU for these signals is a Arduino Uno with a custom shield handling input and output to the color LED
lights, communications via the wireless modem and the PIR train track detection. The signal head and mast
are about 1/4 full size. The signal number plate just bellow the head indicates the signal number and if it is
a home or outer home signal. The square plate indicates it is a home signal and its rectangular shape indicates
there is a speed restriction in the following section. A triangular shape plate indicates it is an automatic signal.
This link is to the signals Uno schematic.
Link to the signals Uno "C" code.
Picture of the bare Uno Signal Shield with 12VDC to 24VDC step up converter.
Picture of the shield with the Uno.
Picture of the shield, PIR detector and 433 mHz wireless modem.
In the next section is a description of the Signal Box control system using a full size 10 lever frame.
The lever frame is connected to a Uno PLC below the floor and the points are pneumatically operated.
The below picture shows the micro switches attached to the bottom of the signal frame. Cables connect the
switches to the Uno PLC. The Uno PLC can be programed with interlocking logic.
This picture shows the cable and PLC frame and other components. At the top is the 24VDC SMPS on the next rung
is the 5VDC SMPS and the Uno PLC and on the next is the cable terminations followed by the pneumatic point
control valves. Not seen is a small air compressor used to supply air to the pneumatic point system.
Link to the wiring layout schematic.
Link to the Uno PLC Schematic.
Link to the Uno PLC "C" code.
The really great thing about this signal system is it is by low cost wireless communications eliminating
the high maintenance and expensive cabling.
For more information on the signalling system please feel free to email me at mike.crean@mail.com
Copyright (c) mgc Perth Western Australia 2015 and on