Model Scenery Tutorials

Comprenshive Tips. Hints And Techniques For Budget Minded Diorama Maker, Model Train Enthusiast And Wargammer

Making A DIY Model Train Turntable Indexing System

Complete instructions on how to make an automatic indexing system for a model railroad turntable.

The system shown below allows indexing up to 12 tracks.

For information about the motor control system, go here.

For information about a drive mechanism, It ignores the drive mechanism go here. Turntable Drive Mechanism.


Materials Required


Circuit Board

Turntable indexing board














Adding The Sensors To The Turntable


Turntable wiring diagram
Turntable wiring diagram


” I mounted a IR LED Sensor (removed from the FC-51s) under each end of the bridge pointing to the wall of the pit.  I also removed the Emitters from the FC-51s as they are not needed.  I paralleled the two sensors and routed the wires through the slip-ring assembly to the FC-51 detector mounted under the pit.  I built my slip-ring because I couldn’t find any that would work 20 years ago when I started my CMR Turntable project.  That is not the case today, there are a bunch of very nice small slip-rings available on eBay now.

I drilled 1/16″ holes in the wall of the pit at the same level as the emitters mounted to the bridge.  A hole centered under each track, you only have to be close to center as the tracks can be tweaked a bit later for perfect alignment.  I purchased the 5mm 940nm IR emitters LEDs off eBay

Behind each hole I mounted a LED Emitter to the wall pointed through the holes to the inside of the pit.  When the sensor LED sees the Emitter through the hole it triggers the FC-51 module and turns the motor off.

The only critical thing is the LED sensors location under the bridge, they must be identical in location, within 1/64″ or better for the bridge position to be accurate on both ends. ”


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