For those of you who have been following my AR-1 versus PSX-AR saga, and for those who haven't, I have discovered something interesting that confuses me.
I received the PSX-AR yesterday in the mail, and I plan to hook it up today. A few days ago, in anticipation of receiving the PSX-AR, I rewired the section of track that will become a separate power district. That section, consisting of 10 passenger station tracks, an 8-track coach yard, and four approach tracks leading into and out of this complex to the mainlines, is, in fact, one large reversing section.
Before I created separate power districts, the entire layout was controlled by a 5 amp booster. I used an AR-1 to control the reverse polarities within this large reversing section. The input side of the AR-1 was connected to the main bus, and the output side of the AR-1 was connected to a single pair of feeder wires tied into all of the feeder wires inside the reversing section.
This past week, while waiting for the PSX-AR to arrive, I added a set of sub-bus wires for this particular power district. Then, at the far end of the sub-bus wires, I connected the feeders from the 10 passenger tracks. Without giving this much more thought, I joined all of the coach yard feeders and the approach tracks feeders together and ran a single set of feeders into the output side of the AR-1, and I ran a set of feeders from the input side of the AR-1 to the sub-bus wires. I then joined the sub-bus wires to the main bus wires, and all worked just fine.
But, this morning, I got to thinking about that wiring arrangement, and I got confused. I am surprised that it worked because feeders from the reversing section of track are wired to the sub-bus which is, in turn, connected to the main bus.
How can this be?
Rich
Alton Junction
If I understand your last question as it is framed Rich, you have made an error if it is so. Every part of a reversable section of trackage, no matter how the individual segments are thereafter configured physically, gapped, and/or wired for power feed, must get their principal and only power via the reverser. If you have the reverser feeding from one end, and the bus that feeds the reverser feeding part of the same gapped arrangement at the same time, you are defeating the PSX-AR.
If it works, it's by sheer luck; you have yet no actual metal tire conflicts at any gaps concurrent to the switching function being effected by the PSX-AR at any one time. So far.
Think of a tree. The main bus is the trunk. There are many branches...the subs. From there, branchlets offshoot, and from those come the twigs. From the latter comes new brouse each spring season. If you place a reverser anywhere, what follows outward from the trunk/branch feeding the reverser must have no other feed but that reverser. IOW, if must all be truly in series.
-Crandell
Crandell, I have not installed the PSX-AR yet.
I still have the Digitrax AR-1 in place.
To summarize my current wiring setup, I installed a pair of sub-bus wires and connected some of the feeders from the reversing section directly to the far end of the sub-bus wires and the remaining feeders from the reversing section to the output side of the AR-1. The input side of the AR-1 is connected to the near end of the sub-bus wires. The sub-bus wires are joined to the main bus wires.
This works, but it surprises me that it does.
Why did I wire it this way? I did not mean to do it that way. What I intended to do was to wire all of the feeders from the reversing section to the sub-bus, run feeders from the sub-bus to the output side of the AR-1, run feeders from the input side of the AR-1 to the main bus and then leave the sub bus isolated from the main bus. But, I got distracted while I was wiring and then lost track of what I was doing.
SO half of the isolated reversing section is connected directly to the bus, and half of it is connected tot he AR-1?
The only way that will work is if you don;t actually have a reverse section, or you aren;t driving a loco past the gaps that isolate it. The AR-1 is just some relay contacts, so unless a short is detected and it reverses, the power just passes right through fromt he inputs to the outpust unchanged, as if you had simply wired that sub bus on the output of the AR-1 right to the main bus, no AR-1 involved. And when it reverses, it's simply wired like a DPDT reverse switch, with the X'd wires on the back. The relay on the AR-1 is wired exactly like that, instead of your fingers moving the toggle switch lever, the electronics activate the relay coil to perform that action.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker SO half of the isolated reversing section is connected directly to the bus, and half of it is connected tot he AR-1? The only way that will work is if you don;t actually have a reverse section, or you aren;t driving a loco past the gaps that isolate it.
The only way that will work is if you don;t actually have a reverse section, or you aren;t driving a loco past the gaps that isolate it.
It is a reversing section, one that has been in place for at least a few years before I rewired it last week. And, I can hear that relay clicking when the loco crosses the gaps and a short is detected.
If I were reading this thread instead of authoring it, I too would reply no way. Yet it works. The one thing that I wonder is if the placement of the feeders from the input side of the AR-1 at the front end of the sub bus wires makes a difference.
Where along the bus you attach things makes no difference.
Are there other insulated joiners in there? Such that the section of track downstream of the AR-1 is actually isolated? It simply cannot work if some of the reverse section is fed direct and some via the autoreverse, there's be a short the moment the reverser switches.
Are the various sections isolated from one another, so that there won't be an indication of a problem until you have driven a locomotive over the tracks?
Don't the auto-reversers have two states: one where their outputs have reversed polarity, and the other the same polarity.
greg - Philadelphia & Reading / Reading
rrinker Are there other insulated joiners in there? Such that the section of track downstream of the AR-1 is actually isolated?
Are there other insulated joiners in there? Such that the section of track downstream of the AR-1 is actually isolated?
OMG, I forgot about that. Yep, there is an insulated rail joiner that I forgot about.
I have some explaining to do - - - LOL
When I first set up this track arrangement for the passenger station / coach yard, I completely isolated the coach yard and the four approach tracks. At the time, I placed one additional gap (insulated rail joiner) just beyond the three 3-way turnouts on that single track feeding into the 10-track passenger station. The cause of the reverse polarity is those two approach tracks coming down from the upper mainlines.
Not long ago, I built a new passenger train consist that proved too long for the existing reversing section, so I decided to lengthen the reversing section by incorporating the entire passenger station. I left that one gap in place because it was hard to reach in order to remove it. That's why when I set up the new sub bus wires, I simply transferred the passenger station feeders directly to the sub bus wires.
Well, duh, no wonder it worked. I forgot all about that gap.
Here is an abbreviated track diagram with the gaps shown as red dots. The 10-track passenger station to the left of that one gap is not shown for simplicity.
Randy, thanks for solving that mystery.