This board is a signal repeater for fascia or above-backdrop mounting.  The board represents 4 "Type D" heads of 3 5mm LEDS each in the format of a standard CTC "Triad" (that is a tall double headed mast, a tall single headed mast and short single headed mast).  Typical applications are for locations where the actual signal on the layout is hidden or hard to see or to provide a positional backup to Searchlight style signals for color-weak operators, or to provide an alternate signal above the layout in areas that become congested during operating sessions. 

See Seth's article on Signal Repeaters published in the PCR Coast Dispatcher and in Layout Design Journal 43

Pads are provided for 0805 SMD resistors (to be selected by the user based on brightness of the LEDs selected, supply voltage and your color sensitivity).  Typical values for 5V are:

Yellow = 220 Ohms

Green = 270 Ohms

Red = 330 Ohms

but your experience may vary with the LEDs used and your color vision

Connections are made via two 8x1 0.100 headers or screw terminals as desired by the user.  See the accessories section for appropriate connectors.

Board dimensions are 2.5 x 3.5"