the wiring shown for the additional bulbs. Note that current limiting resistors are shown. These are only required IF the
voltage provided to the GCP is greater than the rating on the bulbs; most bulbs are rated at 12V AC or DC but you should
check the instructions that come with the signal. If the GCP voltage source exceeds the bulb rating then add current limiting
resistors as shown below; we recommend a value of 100Ω, ¼ watt.
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Figure 3 – Wiring bulb-based crossing signals
Wiring crossing gates
The GCP will directly drive a slow motion motor that
is typically used with crossing gates such as those
from Tomar. Figure 4 shows how the GCP is
connected to a motor; the GCP can drive a
max of
two motors
(one per gate if you prefer to use
separate motors). If the gates are raised when the
signals are flashing and lower when the signals are
not flashing then you simply need to reverse the
motor connections. You can adjust the speed of the
gate motor on the GCP. Using a flat blade
screwdriver insert it into the gate speed adjustment
pot (from the edge of the circuit board, not from the
center of the board). Turning the screwdriver
clockwise will increase the gate speed while turning
the screwdriver counter-clockwise will decrease the
gate speed.
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Figure 4 – Gate Motor Wiring (Tomar example)
NOTE: You must check the instructions for your gate motor to determine the maximum voltage that the motor can
accept. For example, Tomar uses Circuitron’s Tortoise™ which has a maximum voltage rating of 12V DC or AC. If
the voltage provided to the GCP is greater than the rating on the motor then you will need to add a current limiting
resistor (we recommend a value of 390Ω, ½ watt) in the connection path between one of the GCP’s GM outputs and
the turnout motor.
Mounting and wiring the IR components
The IR components should be mounted between the rails. Drill two 11/64” holes,
through the ballast, roadbed, and sub-roadbed. These holes should be located one tie
apart (Figure 5a) and drilled at approximately a 45 to 60 degree angle from horizontal as
illustrated in the side view in Figure 5b. The benefit of mounting them at an angle is
reduced false triggering from overhead light and increased detection reliability in smaller
scales or irregular bottoms on rolling stock. For the smaller scales this drilling may end
up hitting the ties. Take your time so you don’t mangle them! Insert the leads of one IR
emitter (white and black wires) into one of the holes (it doesn’t matter which one!) from
the top of your layout. Repeat for the IR detector (blue and black wires). The tops of the
components should sit no higher than the top of your ballast for optimal IR performance;
in some cases (e.g. false triggering) it may be necessary to locate the components a little
below the ballast line. You can extend the leads with similar (or larger) wire. We
recommend soldering and insulating these connections. We also recommend using
terminal blocks/strips since you’ll have multiple DC and GND connections to make.
Once you have wired the IR components and verified their operation you may wish to
put a dab of white glue or silicone caulk where the wires exit the holes underneath the
layout. This will help to hold the components in place; make sure you don't get any
substance (e.g. ballast or glue) on the top surface of the IR components as this may
prevent them from operating properly. In extreme cases where you may be getting
interference from overhead lighting you can mount the IR detector in some plastic or
metal tubing. You can also recess the IR detector slightly below the ties and roadbed.
Figure 5a
Figure 5b
