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.
Adding The Sensors To The Turntable
” 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.Â 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.Â 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. ”