I have a Digitrax Automatic Reverser Controller (AR1) and have a question about wiring it up to reverse the polarity for locos running onto a turntable. The wiring diagram provided is for a reversing section and is quite clear for a scenario where the reversing section connects back to the same main line from which the loco originated. The turntable, however, will see the train exit onto a new track which could be any of about 6. Can someone kindly provide advice about how to wire the tracks that lead onto the turntable. Please let me know if my explanation of the scenario isn't sufficiently clear, Cheers JamesK
James,
Which turntable are we talking about? Some provide auto-reverse capabilities, some don't.
If your turntable requires an auto reverse unit like the AR-1, you will probably need to treat all 7 approach tracks as one reversing section which means you will need to gap all of the affected rails and wire all 7 isolated tracks to the output side of the AR-1.
Can you provide a track diagram in the affected area?
Rich
Alton Junction
Rich is right about many turntables not needing auto-reversers at all.
If you do need one, though, the auto-reverser should drive only the turntable, not any of the stall or lead tracks. One caveat, though, is if you will be running "through" the turntable, say to put an engine that's longer than the turntable on a stall track that's directly opposite the lead track. In that case, you'll need to make sure that the lead and that stall track have the same polarity. This is only a concern if you will be crossing both ends of the turntable at the same time.
The Atlas turntable, for one, contains specific instructions on how to wire the various tracks to maintain proper polarity.
It takes an iron man to play with a toy iron horse.
If your turntable is one that does need an autoreverser though, The 'portion of the track that loops back on itself' in a turntable is the track on the bridge itself. It doesn;t matter that it might reconnect to any of 6 different tracks - the autoreverser is changing the polarity if the 'loop' part, not the main line - exactly the opposite of the way it works in DC. With DCC, the 'polarity' can change right under a moving locomotive and it has no effect ont he direction of travel. The command sent to the decoder determines which way the loco moves, not the track polarity.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Just a dumb question. Could you not feed the turn table and the stall tracks from the same AR. output and the incoming main track from the primary side?
Lee
Hi Rich,
its the bottom end (ie cheap) Walthers 90 foot turntable. Assuming an auto reverser is required, your suggestion of treating all approach tracks as a single unit wired through the output side of the AR-1 makes good sense. This then leaves the simple matter of wiring the turntable track to the input side of the AR-1. Gapping the approach tracks was the bit which I hadn't considered, but makes perfect sense.
The track diagram consists of three appproach tracks on each side of the turntable, for a total of 6 approaches.
Cheers
James
Hi James,
I am using an AR1 with a Walthers 90 ft. table. The wiring is very simple. You don't have to cut any gaps in any rails, as the turntable is the isolated track, reversing section. The AR1 changes the polarity automatically on the turntable. I have two leads onto the table and 5 roundhouse/ storage tracks. They are all wired into the normal track wiring buss. The one thing I did do was to install an on/off switch on my storage tracks, just so I could turn them off. The TTC screw is for adjusting how often the AR1 switches polarity.
Have fun
Phil
Phil, CEO, Eastern Sierra Pacific Railroad. We know where you are going, before you do!
Hi Phil,
OK that does sound simple. Am I correct to assume that the only wires connected to the AR-1 run to the turntable section? I'm still unclear about the connection between the AR-1 and the lead / storage tracks. Do these need to be connected for the unit to detect the need to change the polarity on the turntable?
I appreciate your advice
Cheers,
JamesK Hi Rich, its the bottom end (ie cheap) Walthers 90 foot turntable. Assuming an auto reverser is required, your suggestion of treating all approach tracks as a single unit wired through the output side of the AR-1 makes good sense. This then leaves the simple matter of wiring the turntable track to the input side of the AR-1. Gapping the approach tracks was the bit which I hadn't considered, but makes perfect sense. The track diagram consists of three appproach tracks on each side of the turntable, for a total of 6 approaches. James
Sorry, I misunderstood your original post.
As long as you wire the six approach tracks the same way, you can treat the turntable track as the reversing section. So, the six approach tracks would all be wired in phase to the main bus wires. A set of feeder wires from the main bus would be connected to the input side of the AR-1. A set of feeder wires from the output side of the AR-1 would be connected to the rails of the bridge track on the turntable.
As long as the turntable track is aligned in phase with the intended approach track, the auto-reverse unit won't even be activated. However, if the turntable is rotated in a manner in which the turntable track is not in phase with the intended approach track, as illustrated in the following diagram, the auto-reverse unit will flip polarities to correct the mismatch.
yankee flyer Just a dumb question.Could you not feed the turn table and the stall tracks from the same AR. output and the incoming main track from the primary side? Lee
Just a dumb question.Could you not feed the turn table and the stall tracks from the same AR. output and the incoming main track from the primary side?
No, that won't work. If the turntable needs an auto-reverser, then the polarity of the rails will flip when you turn it 180 degrees. If you put the stall tracks on the AR, they will flip when the track does, and you will have a phase mismatch.
It looks like Rich gave you the rest of the story, as they say. The main buss wires into the AR1. Output leads from the AR1 to the turntable. All other wiring is done just like the AR1 isn't there. No gaps needed anywhere.
Hi again Rich,
this now makes perfect sense. Feeder wires direct from the bus as input into the AR-1 and I am set. Thanks everyone for the great advice. I will to wire this all up tommorrow, and perhaps I'll log back on and let you know if its been a success
Cheers, James
JamesK Hi again Rich, this now makes perfect sense. Feeder wires direct from the bus as input into the AR-1 and I am set. Thanks everyone for the great advice. I will to wire this all up tommorrow, and perhaps I'll log back on and let you know if its been a success Cheers, James
Just be sure to wire all of the approach tracks the same way. Let us know how it works out. Good luck. I have had great success with the AR-1.
wired it all up and it works really well. I was impressed the AR-1 switches the polarity sufficiently fast that a sound equipped loco doesn't miss a beat. My problem now however is that power to the turntable track cuts in and out as I spin the turntable. Power cuts out at the same position reproducibly. No idea why. Any ideas?
JAmes
I don't have this turntable. I've got an Atlas, and it does have the same issue. On mine, it's because the Atlas doesn't need an auto-reverser, and the "cutout" is the point where it flips polarity on its own.
Maybe someone who owns one of these can answer the question: Does this turntable need an autoreverse unit?
Everything I have found says the 90 foot kit version is NOT auto-reversing, and does NOT have a split ring power pickup of any sort - so the auto-reverser is definitely needed.
Every thread about them in these forums is basically saying how poor a kit this is. Some of the problems include issues with the electrical pickup of the wipers on the bridge shaft. This would suggest there is simnply a design flaw here and the OP hasn;t assembled it incorrectly, it just needs some additional tqeaking to make sure the wipers stay in contact witht he contacts ont he shaft. A careful examination at the point of lost power should reveal where the contact is lost. Search the forums for "walterhs 90 foot turntable" should return plenty of results and mentions of how to get around some of the limitations.
Lift the bridge from the turntable and look at the rings on the bottom. If they are split this turntable does not need an AR1, and I suspect that is the case. The interuption in power happens at the 'no-tracks' location on your turntable.
Let us know.
Dave
From Mt Pleasant, Utah, the home of the Hill Valley and Thistle Railroad where the Buffalo still roam and a Droid runs the trains
Dave Merrill James Lift the bridge from the turntable and look at the rings on the bottom. If they are split this turntable does not need an AR1, and I suspect that is the case. The interuption in power happens at the 'no-tracks' location on your turntable. Dave
The confusion here is due to the fact that Walthers produced two 90' turntables.
The more recent version is similar to the 130' turntable in that it is indexed and has a split-ring feature so that an auto-reverse unit is not required. The more recent version of the 90' turntable has the 'no tracks' location on the turntable that Dave refers to in his reply.
However, the 90' turntable that the OP refers to is the earlier version. It is a kit. It does not have a split-ring feature. In fact, it is not even motorized. It is designed to be installed in a cut-out section of the layout surface and rotated by hand.
When Walthers introduced this 90' turntable kit, it also offered a separate motorizing kit. Once installed, the motorizing kit could be powered to rotate the turntable. Unfortunately, the motorizing kit was not that reliable. The copper wipers did not maintain good, steady contact with the motor, so power losses were frequent.
I originally owned the 90' kit and installed it on my old layout before converting to the 130' indexed version on my new layout. When I had the 90' kit on my layout, I actually cut open the sealed plastic enclosure that housed the motor and the copper wipers. That way, i could access it under the layout whenever problems developed.
I suspect that the OP's problem is either with the copper wipers or the wiring getting tangled as the turntable is rotated. One thing is for certain. The older version 90' kit does require an auto-reverse unit to flip polarities if the turntable is rotated 180 degrees.
JamesK Hi Rich, wired it all up and it works really well. I was impressed the AR-1 switches the polarity sufficiently fast that a sound equipped loco doesn't miss a beat. My problem now however is that power to the turntable track cuts in and out as I spin the turntable. Power cuts out at the same position reproducibly. No idea why. Any ideas? Cheers JAmes
What's happening? Give us an update.
you were spot on abou tthe particulars of the Wlthers 90 foot turntable. I purchased the older version and the motor as a separate unit. There is no question it requires the autoreverser, and that aspect of the job has been very nicely completed. As for the hit and miss power to teh turntable track, I suspect your diagnosis involving the copper 'wipers' is correct. I assembled the kit about 1.5 years ago but had not circled back to make it functional as other layout contruction activities took priority. Perhaps they have rusted slightly? My problem now is it will be very difficult to disassemble the unit to inspect them. My hope is repeated use might in some way solve the problem.
JamesK Hi again Rich, you were spot on abou tthe particulars of the Wlthers 90 foot turntable. I purchased the older version and the motor as a separate unit. There is no question it requires the autoreverser, and that aspect of the job has been very nicely completed. As for the hit and miss power to teh turntable track, I suspect your diagnosis involving the copper 'wipers' is correct. I assembled the kit about 1.5 years ago but had not circled back to make it functional as other layout contruction activities took priority. Perhaps they have rusted slightly? My problem now is it will be very difficult to disassemble the unit to inspect them. My hope is repeated use might in some way solve the problem. James
James, I wish that I could be more supportive of your hope that repeated use might in some way solve the problem. But, unfortunately, it won't. I think that I previously mentioned that when I had this particular turntable installed on my layout, I literally cut out a portion of the plastic motor housing so that I could access the copper wipers from underneath the layout.
Good luck.