TDP & Associates, Inc.

Electronics for the Model Railroader
 

           ServoMaster

The ServoMaster can be used to control two RC servos to provide animations on your layout.  It can
operate three position semaphore signals without any complicated mechanical linkages or stops.  For grade crossings four optical sensors are included to allow single track bi-directional operation or dual track single-directional operation.  Expansion kits will be available soon to allow up to three additional bi-directional tracks to be added.  The SignalMaster will also control the crossing gate lights (directly for common anode LEDs) and an output is provided to add a bell module.  It can also be used to control switch points and anything else that needs to be moved on your layout (I use it for a coal dumper).

The ServoMaster requires a power supply of 9 to 16 volts (AD or DC) rated for at least 500 mA.

The positions are set using a screwdriver adjustable pot.  When in position programming mode the servo's
position follows the position of the pot.  Simply setting the input and pressing a button will lock the position
into memory.  You can also program the movement speed this same way (the movement speed varies
with the pot's position). 

The sensors supplied for use as a grade crossing controller use ambient light to detect the presence of a train.  There are four sensors on the included cable.  These sensors are 'paired' as a 'start' sensor and a 'hold' sensor.  When the 'start' sensor is triggered by the passing of a train the grade crossing sequence is started.  The gates will stay down until the hold sensor is triggered (by the train covering it up) and then clearing (when the train has past).  The gates will then go up and the lights will go out. 

The expansion kit adds one additional sensor cable giving you four start & hold sensor pairs.  These can be used to give two bi-directional tracks or up to four single directional tracks.  Additional expansion kits can be added up to a total of eight start & hold sensor pairs (four tracks bi-directional tracks).

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Last modified: 04/03/07