Turntable Drive/Control mechanism

I am considering building a turntable for my LGB trains, utilizing an
old (record) turntable as a rotating platform. I plan on motorizing
the turntable usng a small DC motor, some gear reduction and a couple
of switches.
I am looking for ideas on how to electronically control/index the
turntable so I could simply move a selector switch and have the table
rotate to the appropriate position.
Reply to
Paul Lizanich
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This is a good move - you're guaranteed a smoothly turning turntable.
Try using a rubber sleeve on the motor shaft running on the outside edge of the record turntable. Mount the motor on a pivoted arm sprung lightly against the disk. (no gears to grind and whirr)
Cams screwed to the top edge of the disk operating micro switches. From my experience, I would recommend separate cams and switches for each direction to avoid the need to make the complex adjustment of both position and throw for single cams.
IR diodes and IR detectors - turn on the IR diode aligned with the required track - detector turns off motor. The problem then arises as to how much momentum remains in the drive :-)
Regards, Greg.P.
Reply to
Gregory Procter
1. If you enjoy playing with microcontrollers/microprocessors -- or have a (good) friend who does -- you can work this problem by having a "getting close" detector before the position detector.
2. Rather than using continuous motors, you can get steppers with very small incremental motion that look completely continuous but can stop on a dime.
Reply to
Norm Dresner
could you please send along bibliography or something so I can get more info on using infra-red controlling?
Reply to
larry l.
"Complete book of Model Railway Electronics" Roger Amos ISBN 1-85260-288-0
It's simpler than you might think - An Infra-red LED and matching sensor from a local electronics shop and a sensing circuit, perhaps a 555. The LED shining on the sensor alters the resistance of the sensor which flip/flops the 555 and drives a relay or transistor or TTL logic or ...
I've never seen a published circuit devised for a turntable but all you would be doing is interupting current to the driving motor with the cams and micro-switches and adding parallel electronic switches so that only the one IR lighted TT track end electrons switch is "off".
The mechanical problem then is that the electronic on/off is on the revolving bridge and all the other control circuitry is on the baseboard. BTW, I prefer the drive mechanisim on the baseboard rather than on the TT bridge as it's much easier to quieten the mechanisim and everything can be built to blacksmiths standards rather than microsurgery standards. :-)
Regards, Greg.P.
Reply to
Gregory Procter
adding parallel
switch is "off".
There's at least one detailed description of an opto-electronic indexing system on the web, just do a bit of searching. The links page at is a good place to start, look under 'Model Railway Electronics. Keith Make friends in the hobby. Visit Garratt photos for the big steam lovers.
Reply to
Keith Norgrove
Have you looked at Malfunction Junction?
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" Paul
Reply to
Paul Newhouse
Paul, years ago "floppy drives" for computers were powered by "Step Motors". If you have an old computer laying around check to see if the floppy drive does indeed have this type of drive and the electronics to go with it. You should be able to adapt this to your needs. Glenn
Reply to
Glenn Patterson

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