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been a while since I played with DCC, need to make sure I'm doing it right... Track and electrical/DCC
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New member 17 posts albabe New member 17 posts
albabe

Hi everyone-

I've been working on a basement sized layout for the past zillion years. See attached jpgs. The basement is roughly 40 x 25, so the layout takes up roughly 700s.f. It's been a long while since I played with DCC, so I'm re-reading books and visiting the Digitrax website to refresh my memory. I'd love for some feedback on what I'm doing.

Some notes on the layout: 5 sections are existing parts of Pliny Holt's Oakland Mole layout. The layout was controlled with C/MRI and I'm planning on changing it to DCC (some control aspects I want to save, but I'll worry about those later). The existing sections are the Oakland Yard and the Mole/Pier and the return loop Walnut Creek (lumber section in the upper left of the first image). Everything else I've built from scratch. I'm planning on 8 power districts (2 PM42s) and will try to balance anticipated loads on the two PM42s (eg, yard on one PM42, mole on the other). The trolley lines, for now, are being wired as two rail but will be converted to overhead in the future. When I convert to overhead the reversing sections go away as the two rails get tied together.

On the drawing the reversing sections are in cyan (a turntable at Walnut Creek, a reverse loop and wye on the trolley line, a turntable and wye in the yard/mole, and a reverse loop on the east mainline.

I have the following Digitrax equipment already: DCS 100 (Super Chief - older model), DB150 (Super Empire Builder - old model), PS 515, PS 12, UR90, UP5 (qty 7), PM42 (qty 3), se8c (qty 2). So I'll need to buy a few more pieces to complete what I'm hoping to accomplish in the second drawing.

For the DCC schematic I have the following questions:

1) is it correct?

2) does the ground wire need to go to the DB150 (the SEB manual didn't indicate it when using the DB150 as a booster)?

3) I found reference on the Digitrax website that the PS12/14 should not be used to power more than 10 devices (I'll have 19 - 2 PM42s, 12 panels, 5 se8cs). Will what I have drawn work or will I need to split the devices into smaller groups and provide power from 2 or 3 PS14s?

4) any other thoughts?

FWIW, I'm starting to connect the track feeders to the bus wires and am testing things with an old analog throttle before hooking up the DCC...

-alex-

Alex M. Postpischil

Winston-Salem, NC
Reply 0
akarmani Regular poster 298 posts
akarmani

In the ball Park

Looks like a great start. I love the layout. I will answer your question in order:

1. Generally it looks correct

2. I believe the ground pin is there to ground the configuration pins (A&B). You grounded config A to make it a booster which is correct. I would not ground your boosters together. You may want to call Digitrax on this. I have always found there tech support great.

3. The power supplies will not work as drawn. You will need more. I would power your two PM42s with your PS12 as drawn. Each PM42 requires 125ma of current and the PS12 provides 300ma at 12volts.

I would power your 12 panel (UPs and URs) with three PS14s. I would put the 10 UPs on one PS14 and put each UR on its own PS14. The PS14 can handle 10 UPs, but I am unsure of the power requirement of the URs. This is a little overkill because I would think you could get away with spitting the 12 panel (UPs and URs) between two PS14s. For the price of one more PS14 it may be better to go with three. It also may be more convent to just use three PS14s.

Each SE8C requires 100 ma of current and a PS14 provides 300ma. Therefore you would require a minimum of 2 PS14s for the 5 SE8Cs. I would put 2 SE8C on 1 PS14 and 3 on the other. If your have any problems with the 3 SE8C on the 1 PS14, you could get another PS14 and move one of the SE8C to its own PS14, so that no more than 2 SE8Cs are on 1 PS14.

4. The number of power supplies can also be driven by location of the components and convenience. In another words, if your PM42 are not located next to each other than it may be better to power them by two separate power supplies than run long power wires across/around the room. I have seen a few layouts that cluster their booster and power managers together and then run long track buses to the track. It may be convenient, but the goal is to keep the track buses short and let the AC house power and loco net cover the distance.   

Hope I helped.

 

 
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albabe New member 17 posts
albabe

Thanks

I'll check with Digitrax on the ground wire as you suggest.

As for #3, just goes to show that I really don't know the power requirements of the devices... I'll have to look at that a bit because there is a limited number of outlets in the basement (I removed all the wiring on the exterior wall because of evidence of prior water issues which seem to be gone now). I'm hoping to not wire high voltage on the layout, but could run new outlets/power around the support structure.

For #4 that is what I am doing - the DCS, DB, and PM42s are all in one central area and I've got 12ga wire for power buses radiating out.

Thanks for the feedback.

-alex-
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Bruce Petrarca Frequent poster 920 posts
Bruce Petrarca

Questions for Digitrax

Alex - Nice to see someone think about their railroad and draw a schematic. Ask Digitrax, but I believe you will want the ground as drawn. FYI, the faceplate of the UP5 units are system ground, too. A convenient place to discharge static electricity, before you strain the electronics by putting it on the track! I don't know of any reason to connect the PM42 units to the LocoNet. There is a connection of the DT400 to set them up. Again, check. The only thing I can see that I don't think you will be happy with in the long run are the PM42s. They are difficult to wire - I charge $100 to wire each one if a customer insists on having them. They are an archaic relay driven design. They make a huge spark (damaging wheels and track) before they throw. The combination of the Digitrax boosters and the PM42s are NOT sound-loco friendly. More than about two sound-equipped locos in a district and the system won't recover from a short without removing the locos from the district. And I could go on, but you have the high points! I recommend PSx units, available at most DCC dealers. They are just two wires in and two out to the track. They have double connectors on the input for easy daisy-chaining. They come from the store programmed for 3.75 amp trip current, perfect for the Digitrax boosters. You will want to add a single jumper (J7-3 to J7-4) to tell each unit that you are using a Digitrax booster. DCC Specialties keep changing the name of that jumper. They should just call it the "Digitrax jumper" and be done with it. With the jumper in place, they will allow the digitrax booster to restart with as many as 16 sound-equipped locos in a single district. There is No need to program the unit(s). However, if you do need to program them, it can be done by selecting programming mode with a jumper on the board and programming on the main. No need to plug the throttle into the board!

Bruce Petrarca, Mr. DCC; MMR #574
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albabe New member 17 posts
albabe

from digitrax and other thoughts

Digitrax says no need for the ground wire between the DCS100 and DB150.

I was thinking about the PSx units, but looked at pricing. Since I have the PM42s and am currently unemployed I can't justify the expense right now. I won't be running sound units (well maybe one that I have), so that's not an issue.

I'm not sure I would call the PS42s difficult to wire, the drawing from Digitrax looks straightforward - maybe about 10-15 minutes. ...which would be a pretty good markup at $100 each...maybe I should do that stuff for a living!

Connecting PM42s to Loconet is optional from Digitrax, but I saw a note somewhere about using JMRI to monitor them (and set them up) - which I will be doing. I'd rather have a GUI to do the setup...

-alex-
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Bruce Petrarca Frequent poster 920 posts
Bruce Petrarca

I got my first soldering iron when I was 7.

That was 55 + years ago, just to calibrate. PM42s take me about two hours to wire correctly and neatly. Understand the price issue. Suggest you use barrier terminal strips, or something similar to make it easy to change later! Also, I'm going to disagree with whomever at Digitrax. If you put a 16 to 18 AWG ground wire between the boxes you are duplicating the ground that is part of LocoNet. In the event of a component failure, your 22 AWG, or so, LocoNet wire could take the full power of both power supplies, 10+ amps! I think it is safer with an external ground with some heft to it!

Bruce Petrarca, Mr. DCC; MMR #574
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albabe New member 17 posts
albabe

another Q on power supplies for the accessories

I'm just wondering if I could use another PS514 to create a bus for the UP, UR, and SE8C devices. Set the output voltage at 13.8V and run a bus along the layout and tap in for each device... That would certainly give me enough power for all 17 devices. The Digitrax document says one PS14 can power up to 10 UP or UR devices (so I'm assuming they each draw less than 30mA). So 12 UP/UR = ~360mA and 5 se8c = ~500mA for a total of less than 1A. Just wondering...

-alex-
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