PM42
June 2012 Status - What, its not June
Yeah, this is a bit late. I’ve been distracted. I’m throwing this up so I can summarize what did get done, before moving on.
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More Wires
After saying I was going to finish up the DCC electronics several times, I’ve finally made a start. There are two parts to this. The first is finishing up the remaining DCC power protection and occupancy detector panels. I did the first three tables last year, starting around January. The third was the first I’d done as a removable panel, which I wired up back in November. At the same time I’d begun the work of setting up a third accessory power bus, adding a switch and meter to the main panel. However at that point I’d stalled, with my attention off the layout over the holidays, and when I returned it was to work on buildings.
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Bus Wiring and November 2011 Status
DCC is often said to simplify a model railroad because it requires “only two wires”. While that’s true to an extent, most real model railroads will require quite a bit more. Or maybe I just like to over-complicate things.
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DCC Power II
The DCC Power work continues, but it’s still not done, as I have to do the power panels for the urban scene and the unsceniced return loops, but with the panel I built and tested back in September/October finally installed under the tables of the River Crossing scene, I’m at the halfway mark (having done the Riverside Station scene back in March).
To recap, the board contains a PM42 DCC circuit breaker that provides four separate circuit breakers and a BDL168 occupancy detector that can provide up to sixteen occupancy detectors and eight transponding sensors (see my pages on occupancy detection and the BDL168 for more details). This board provides occupancy detection for six electrical blocks, two each on the commuter tracks and one on each subway track where it loops below the expressway. Although I’m also wiring up the transponding sensors, as mentioned previously I’m having doubts about them due to problems in testing and the anticipated low power draw of my trains being borderline to register on them.
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To recap, the board contains a PM42 DCC circuit breaker that provides four separate circuit breakers and a BDL168 occupancy detector that can provide up to sixteen occupancy detectors and eight transponding sensors (see my pages on occupancy detection and the BDL168 for more details). This board provides occupancy detection for six electrical blocks, two each on the commuter tracks and one on each subway track where it loops below the expressway. Although I’m also wiring up the transponding sensors, as mentioned previously I’m having doubts about them due to problems in testing and the anticipated low power draw of my trains being borderline to register on them.
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Fun with JMRI II and September 2011 Status
I’ve been playing around with JMRI some more, and trying to debug my transponding problem with the first of the electronics boards. This is really baffling. I checked the wiring, and it was fed through the RX sensor properly. I replaced BOTH the PM42 and the BDL168 circuit boards (I’ve got a stack of them waiting for more electronics boards once I get this one working) and I tried using other blocks. And I had more transponding sensor failures. On both sets of RX sensors. One defective set I might accept, but two?
So I tried a variety of things, and noticed that the non-functional detectors would, every once in a while, work. In fact, I discovered that with the train motionless, one of them would periodically cycle from detection to non-detection, emitting a LocoNet message reporting the change in status each time. I tried moving the wires. I pulled a fresh RX1 set out of a bag, and set it up atop a trash can (see above) with every wire fed through it fully separated from every other wire in mid-air (about the middle of this I was holding things in both hands and wishing I had a third arm). And that failed too, reliably as it were.
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So I tried a variety of things, and noticed that the non-functional detectors would, every once in a while, work. In fact, I discovered that with the train motionless, one of them would periodically cycle from detection to non-detection, emitting a LocoNet message reporting the change in status each time. I tried moving the wires. I pulled a fresh RX1 set out of a bag, and set it up atop a trash can (see above) with every wire fed through it fully separated from every other wire in mid-air (about the middle of this I was holding things in both hands and wishing I had a third arm). And that failed too, reliably as it were.
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DCC Power I
After assembling the first of my DCC protection and Occupancy Detection boards, I decided I wanted to test it and get some experience with using it. So I set up my loop of test track with insulated rail joiners separating it into two halves, and connected the feeder to outputs 1 and 2 of the BDL168, which correspond to RX4 A, detectors A & B. All of these are powered by PM42 section 1. For DCC, I used my Zephyr, and for the DC supply I used the 2 Amp, 12 Volt supply I plan to use for these systems (it’s the black box just above the Zephyr in the photo above). Powering it up, nothing went “Zap!”, which I count as a success.
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Back On Track
11 September 2011 22:24 Filed in: Electronics,Administrivia
After two months spent working on the website move, I’m back to working on (and playing with!) the railroad. That doesn’t mean I’m done with the website stuff. There are still pages left to convert, and a few problems to solve, and I’ll have more to say on that down below. But the new one is up and running, and relatively problem-free. And I’d budgeted this weekend to model railroad work in case there were problems, so I had some free time on my hands. I celebrated by getting the outer loop wired up and running a couple of trains. Then I turned my attention to working on the DCC protection and occupancy detection circuits so I can get the other two loops up and running.
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April 2011 Status, Subway Station Planning and a Bus System
April sped by rather quickly, as least in part because I had some non-railroad distractions that took me away from the layout. Not much was done in concrete terms, but planning for the Riverside Crossing Subway Station made good progress. Mostly I acquired parts for some more power management wiring (PM42 circuit breakers, BDL168 occupancy detectors, and RX4 transponding sensors, as well as wire, terminal strips, and miscellaneous connectors). I also painted several sheets of cut-to-size plywood with primer, to which I’ll attach all the electronics and wiring. Then I’ll hang the plywood under the layout, where it can be easily wired to terminal strips, but remain far enough away from the track and bus wires to avoid interference with the transponding sensors. I’ll have more on this after I’ve built the first of these.
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February 2011 Status - Occupancy Detection Revisited
Work has progressed slowly this month, partly from distractions, and partly because I’ve been reluctant to finish up the block occupancy detector wiring. I finally realized that the reason for this was that I wasn’t happy with my hybrid approach to occupancy detection and transponding.
To recap, my Subway and Commuter loop tracks were to be divided into blocks, with Digitrax BDL168 occupancy detectors and PM42 circuit breakers (circuit breakers are typically one per track per table, whereas there may be two, three or even four detectable track sections on a single track on one table, and more in a couple of cases). The PM42 provides for four circuit breakers, which is a nice fit for the four tracks, and the BDL168 is divided into four independent quadrants (so each can be wired to a separate circuit breaker), each with four block detectors. I’d originally planned one PM42/BDL168 per scene, meaning that wires would have to cross a table boundary in the Urban and Riverside Station scenes.
And that was a problem, for several reasons. First, running wires between tables violates my “keep all wires except bus wires local” design goal (it makes the layout harder to disassemble), second while the BDL168 can support 16 occupancy detectors, in some places I needed more than four on one track, which broke the association of the PM42 circuit breaker element to a single track, meaning a short would shut down a second line. And finally, I wanted to do Transponding, and the BDL168 only supports 8 transponding sensors (using a pair of RX4 sets), meaning some blocks would be able to report which train was in them, and some would only be able to report that some train was present, but not which. None of these were fatal flaws, but they were eating at me. And I finally realized that I only needed two more sets (seven instead of five) to fix these problems.
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To recap, my Subway and Commuter loop tracks were to be divided into blocks, with Digitrax BDL168 occupancy detectors and PM42 circuit breakers (circuit breakers are typically one per track per table, whereas there may be two, three or even four detectable track sections on a single track on one table, and more in a couple of cases). The PM42 provides for four circuit breakers, which is a nice fit for the four tracks, and the BDL168 is divided into four independent quadrants (so each can be wired to a separate circuit breaker), each with four block detectors. I’d originally planned one PM42/BDL168 per scene, meaning that wires would have to cross a table boundary in the Urban and Riverside Station scenes.
And that was a problem, for several reasons. First, running wires between tables violates my “keep all wires except bus wires local” design goal (it makes the layout harder to disassemble), second while the BDL168 can support 16 occupancy detectors, in some places I needed more than four on one track, which broke the association of the PM42 circuit breaker element to a single track, meaning a short would shut down a second line. And finally, I wanted to do Transponding, and the BDL168 only supports 8 transponding sensors (using a pair of RX4 sets), meaning some blocks would be able to report which train was in them, and some would only be able to report that some train was present, but not which. None of these were fatal flaws, but they were eating at me. And I finally realized that I only needed two more sets (seven instead of five) to fix these problems.
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Almost There - January 2011 Status
January went primarily to the backdrops and the risers/inclines of the Riverside Station scene commuter loop, and now the Riverside Station scene begins to come together. The tables themselves are not yet connected to each other or anything else, as I’m taking the opportunity to work on the wiring with them stood on edge, which is much easier than working on it from below.
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Scotty I Need More Power!
25 July 2010 00:12 Filed in: Electrical,Electronics
DCC doesn’t need to be complicated. At the simplest, it’s a pair of bus wires from the command station running under the track, with feeders connecting the track to it at intervals. I can, however, make anything complicated. Probably more complicated than it needs to be. It’s a talent.
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More Electrical Work
Rather than turning my attention immediately to the Riverside Station scene, I decided to get the electrical systems ready for the eventual use of the two “ground level” loops, which will require DCC. And that meant I needed to finalize my plans. And although most of them had been worked out last year, and revised (in my head if nowhere else) over the winter, there was still a bit of planning needed before I was ready to start cutting wire. This had to encompass the DCC systems (both power and the LocoNet control bus) as well as the various power strips to supply them, and some additional power supplies for eventual LED lighting. I’d started thinking more intensely about this while I was working on the wiring recently, but needed to bring that to conclusion and write down the results.
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