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Using photocells for train detection 

The  photocells  should  be  mounted  between  the  rails  in  the 
general  area  where  you  will  locate  the  signal.  Drill  a  9/64" 
hole  through  the  ballast,  roadbed,  and  sub-roadbed.  For  the 
smaller  scales  this  drilling  may  end  up  hitting  the  ties.  Take 
your time so you don’t mangle them! Figure 5  illustrates the 
placement of a photocell in between the rails. Insert the leads 
of the photocell into the hole from the top of your layout. One 
of the photocell leads has a piece of insulation on it so be sure 
the two leads don't touch each other! If the leads do not 

 

Figure 5 – photocell placement 

protrude enough from the underside of your layout then it will be necessary to extend the leads; soldering wires to them is the 
most common method; make sure you insulate any connections you make to the photocell leads so that they don't short out. 
Once you have wired the photocells to the 

Grade Crossing Pro/2

 and verified their operation you may wish to put a dab of 

white glue under the photocell to hold it in place; make sure you don't get glue on the top surface of the photocell as this may 
prevent it from operating properly. Figure 6 illustrates the photocell wiring; make sure you have the photocells in the correct 
order as shown at the top of page 1. Photocells do not have any polarity so you can connect either lead to the GND terminal 
and connect the remaining lead to the appropriate photocell input.  
 

Photocells  require  a  light  source  above  them  to 
function  properly.  On  most  layouts  the  room 
lighting  should  be  sufficient.  However,  if  the 
photocells are located in an area that doesn't get 
much overhead lighting or if you have simulated 
"nighttime" operations  then it  will be necessary 
to  locate  light  sources  on  the  layout  near  the 
photocells.  Streetlights  and  yard  lights  are 
common  light  sources.  Locate  the  light  sources 
slightly to the left or right of the photocells and 
not directly over them; this will allow the 

Grade 

Crossing  Pro/2

  to  still  properly  detect  a  train 

that has stopped over any photocell with the gap 
between cars over a photocell. 

EN

EF

WN

WF

 

 

Figure 6 – Photocell wiring

 

 

 

Photocell sensitivity setup 

You can adjust the sensitivity of each photocell on the circuit board using a small slotted head 
screwdriver. Along one each of the board are four potentiometers  (or  “pots”)  that are  labeled 
"WF", “WN”, “EN” and “EF”. The 

Grade Crossing Pro/2

 supports a SETUP mode to  make 

this adjustment process easier. To enable this mode, you must have the switch labeled SETUP 
in the ON/CLOSED position as shown in Figure 7. In this mode the signals will not flash. The 

Grade Crossing Pro/2

 circuit board contains four sensor status LEDs; one near each of the four 

adjustment pots. These LEDs will assist you in setting the photocell sensitivity.  

 

 

Figure 7 - SETUP mode

 

  Now follow these steps after you have connected power (see page 9) to the board:

 

 

1.

 

Remove all obstacles that may be covering the photocells or blocking overhead light to them. 

2.

 

Insert the blade of the screwdriver (from the edge of the circuit board, not from the center of the board) into the 
adjustment pots, one at a time. Turn the screwdriver completely counter-clockwise (left) in all FOUR of the pots. 

3.

 

For the adjustment pot labeled WF turn the screwdriver clockwise (right) until the red LED near the pot just lights 
up. Then turn the screwdriver back counter-clockwise until that LED goes out. 

4.

 

Repeat step 3 for the three remaining pots with corresponding LEDs. 

5.

 

Exit SETUP mode by putting the SETUP switch in the OFF/OPEN position (“operational” mode). The flashing and 
other action should now operate properly. It may be necessary to repeat this procedure if layout lighting conditions 
change significantly. 

Note that the 

Grade Crossing Pro/2

 will activate the sensor status LEDs when the associated 

sensor detects a train in “operational” mode; this is different from the previous generation 

Grade Crossing Pro

!

 

 

Turning the pots clockwise adjusts for brighter overhead lighting conditions while turning the pots counter-clockwise 
adjusts for dimmer overhead lighting. 

Summary of Contents for GCP/2

Page 1: ...IR4 if you want to change types The board is also offered without sensors version GCP 2 X for use with other brands of external detectors The infrared detection method has been improved and no longer...

Page 2: ...2 is in sensor setup mode TRUE LAMP2 Signals don t fade on off like modern signals Signals fade on and off like older signals SEN TYPE Sensors are photocells or external current detectors Sensors are...

Page 3: ...required IF the voltage provided to the Grade Crossing Pro 2 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 sign...

Page 4: ...iring 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...

Page 5: ...them this will allow the Grade Crossing Pro 2 to still properly detect a train that has stopped over any photocell with the gap between cars over a photocell EN EF WN WF Figure 6 Photocell wiring Pho...

Page 6: ...the ties and roadbed Figure 8a Figure 8b Using across the rails infrared With this sensor mode and physical arrangement a train is detected when the infrared IR beam is broken by the train The IR comp...

Page 7: ...f the four photocell sensitivity adjustment pots NOTE The four adjustment pots have NO affect when using either infrared sensor mode Do the following after you have connected power see page 9 to the b...

Page 8: ...the SPKR outputs as shown in Figure 13b You can adjust the volume of the bell sound using the potentiometer labeled VOLUME next to the SPKR terminals Figure 13a Location for bell module 8 Figure 13b...

Page 9: ...re flashing ON OFF OFF Rings continuously while signals are flashing ON OFF ON Stops ringing as the train clears but before flashing stops ON ON OFF Only rings while gates are lowering or raising ON O...

Page 10: ...The problem with this implementation is that the Grade Crossing Pro 2 cannot differentiate between two trains traveling in opposite directions on different tracks As such it could easily get confused...

Page 11: ...no train is present then you will probably see one or more of the red sensor LEDs lit up on the Grade Crossing Pro 2 board You may have the IR components sitting too high Make sure they are no higher...

Page 12: ...e 2 If the product has been altered in any way e g soldering to the circuit board 3 If the current or voltage limitations of the product have been exceeded Requests for warranty service must include a...

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