DCC Conversion Reverse Loops

Diesel2000

Diesel2000

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Hi everyone, I'd like to get some feedback on my layout design and configuration, specifically the addition of a multi-direction reverse loop. I'm in the process of converting my layout from DC to DCC and currently have a mainline and yard as seen in the first pic - pretty simple stuff. I have them isolated according to the color codes by using 1 PSX circuit breaker for each block.

I want to expand a bit and add an inner loop that can reverse in either direction. I designed the layout in pic 2 using an LGB 12260 double slip crossover switch. I received some help in figuring out the placement of the PSX-AR units, which are the red, orange, and blue blocks. Green and yellow continue to be connected to PSX blocks. So the requirement to make this work is 3 PSX-AR in addition to the 2 PSX breakers. Does this seem correct?

I want to make sure I get this right before I start digging and laying more PVC conduit in the ground as this layout is outside along the side of the house. I plan to run a separate accessory bus to power all the switches and keep them isolated of any potential short on the mainline, inner loop, and yard.


BRR_Yard.JPG
BRR_Reverse_AR.jpg
 
Greg Elmassian

Greg Elmassian

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I would concur on the PSX-AR units for autoreversing, used by most clubs due to reliability and adjustable levers, and they just work.

They can be located on the layout at the "boundary" between the mainline and the reverse loop... i.e. no extra wiring. A small weatherproof enclosure inside a lineside structure...

You only need one autoreverser in the red area. Adding the breakers to the yellow and blue areas is optional and can be done at any time, again remotely locating them, but this case I would run rail clamps, put a heavy gauge feeder every 30-40 feet, and isolate those power districts, so maybe 3 feeders.

You could feed the switchyard separately if you think there will be a bunch of operating there, or a number of locos. Your yard needs at least a lead track so switching does not foul the main:


See if that helps...


Greg
 
Diesel2000

Diesel2000

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Thanks Greg, so you dont think I need the 3 AR units here, just 1 for the inner loop (red) below the LGB 12260 double slip? This was my original design and it keeps wiring changes to a minimum, but I wasnt sure if it would work for auto reversing in both directions through the inner loop and out the double slip/crossover. See pic below. Here I would have 2-3 feeders on the mainline in green on a PSX (just over 90ft), another PSX for the yard depending on draw, and then the AR for the inner loop.

For the yard I just plan to have trains parked and ready to hit the mainline, which is why I went with entry/exit on both ends parallel to mainline.

BRR_Inner_Reverse.JPG
 
Greg Elmassian

Greg Elmassian

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Only one autoreverser is needed, if you want separate breakers that's ok, but really only needed if you are running lots of locos at once, or if there is a lot of activity in the yard and shorts would occur from adding/removing locos and cars.... then a short there would not affect the rest of the loco...

The autoreverser will "sync" "polarities" when a loco crosses either insulated joint between the red and the green. The cool thing about DCC is no matter how you change the "polarity" the loco direction remains constant.

Now if you were running DC, then you would need more autoreversers since you have to "adapt" where the loco is to where it is coming from.... so entry into new areas requires they reverse also.

If you have to run DC sometimes, just do not enter the reversing loop area (red)

Greg
 
Diesel2000

Diesel2000

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Thanks for that Greg.

I did some rework on my design as I wanted to eliminate the hard S curves both in and out of the yard, and make better use of the space I have for the yard. Pretty excited now to get building this out. The layout will be DCC, but the mainline will still be able to operate with DC.



I'm using the heavy duty Split Jaw power connectors and want to add a 3rd feeder for the mainline as I move to DCC. I currently have ring terminals soldered to 10 AWG feeder wire and attached around the tightening screws (not using the wire bed slot in the connector) and was wondering if anyone has used this method to then daisy chain between connectors? This will be easier than tapping a main bus I think as my layout will have 3 blocks, and I only need multiple feeders on the mainline due to length.


BRR_New_Yard_Inner_Reverse.JPG
 
Greg Elmassian

Greg Elmassian

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Normally a "star" configuration is recommended, i.e. each feeder is a "home run" back to the power source.

Daisy chaining is to be avoided if possible.

Several reasons:
1. with home runs, you can isolate 3 separate power districts of the layout (use insulators between) and it becomes WAY easier to locate bad joints.
2. it's better signal wise for DCC (long discussion)
3. every connection is a place to add resistance, which means voltage loss. with home runs, you have one connection at the booster and one at the track, daisy chaining just adds many more connections, potentials for voltage loss.
4. a variation on #1, if you are debugging and you daisy chain, then you cannot easily disconnect the first 2 power districts.
5. separate power districts means you can add breakers to each one, so a derailment in one allows the others to continue
6. a variation on 5, if the entire layout needs 10 amps, but you have 3 power districts, you can set breakers to a lower trip current, and believe me, that can save a loco in case of a derailment... on a 10 amp breaker, you can push 9 amps through a short through a loco and melt stuff down and never trip the breaker.

Those are just a few benefits off the top of my head.

Greg
 
muns

muns

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Just one thought....isn't the LGB Double slip all live (like the switches/points) and thus will cause a short in the above diagram (due to the slips)?
 

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Greg Elmassian

Greg Elmassian

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Might be, not an LGB DS expert, if so, then put one of the insulators "north" of the switch? Whatever way it is wired, should be a simple solution. We could look at an LGB diagram and see maybe.
 
Diesel2000

Diesel2000

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Just one thought....isn't the LGB Double slip all live (like the switches/points) and thus will cause a short in the above diagram (due to the slips)?
I had wondered about this and was thinking the same - I can put the isolation clamps to the north of the switch, which should take care of a short that happens in either direction into/out of the loop
 
Diesel2000

Diesel2000

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This makes sense from a resistance and voltage drop standpoint. I've settled on 3 power districts total (using breakers PSX and AR) and the mainline will have 3 feeders, so one every ~30 ft. I dont see much value in splitting the mainline into multiple districts given that it is just a loop and a short could end up with a live train ramming the back of the shorted one.

I'll be adding 16 switches to the layout with the yard and inner loop and plan to run those from a separate switch bus that is powered independently. I want to have all 12 amps available for locos as there is a small grade on the south end of the loop, and it will allow for switch operation even if there is a short. That is going to be a lot if wires to run to the 4 channel Massoth switch decoders.
 
Greg Elmassian

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Have you calculated the current draw on the switch decoders, they should be minimal, I run 7 four-unit decoders off my mainline... and that is with the twenty six 24v solenoids to drive the pneumatic switch motors.

Greg
 
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phils2um

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I agree with Greg - if you are running DCC on your line it makes absolutely no sense to run separate power for turnout decoders scattered all over the place. The power draw of a turnout motor is minimal and only momentary. You are very unlikely to throw more one at a time. Even two will require only one amp or less. And, again it's only momentary. Each decoder itself typically draws less than 50 milliamps continuous which is insignificant. The single greatest advantage of DCC is eliminating tons of wiring while still being able to run multiple trains. This is a huge bonus outdoors. Take advantage of it! Connect your turnout decoders to the track wherever it is most convenient.

From experience I also second Greg's recommendation that you have separate isolated track districts wired as a star rather than a loop. However, unlike analog control you do not need a bunch of them. Between two and four are probably all that are required depending on the layout complexity. Concentrate on multiple solid power connections to each district and keep each run as short as possible. This will ensure you have hardly any voltage drop and more importantly a clean DCC signal to all your decoder equipped devices. You can initially power the layout with a single booster at the source. Then, in the future if you think more power is required, you can supply each district or groups of districts with their own booster.
 
dunnyrail

dunnyrail

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I agree with Greg - if you are running DCC on your line it makes absolutely no sense to run separate power for turnout decoders scattered all over the place. The power draw of a turnout motor is minimal and only momentary. You are very unlikely to throw more one at a time. Even two will require only one amp or less. And, again it's only momentary. Each decoder itself typically draws less than 50 milliamps continuous which is insignificant. The single greatest advantage of DCC is eliminating tons of wiring while still being able to run multiple trains. This is a huge bonus outdoors. Take advantage of it! Connect your turnout decoders to the track wherever it is most convenient.

From experience I also second Greg's recommendation that you have separate isolated track districts wired as a star rather than a loop. However, unlike analog control you do not need a bunch of them. Between two and four are probably all that are required depending on the layout complexity. Concentrate on multiple solid power connections to each district and keep each run as short as possible. This will ensure you have hardly any voltage drop and more importantly a clean DCC signal to all your decoder equipped devices. You can initially power the layout with a single booster at the source. Then, in the future if you think more power is required, you can supply each district or groups of districts with their own booster.
I doubt a booster would be required for this layout unless multiple lashups of heavy juice guzzling US Diesels are involved. My plan when into Track Power was to have a feed at each end of what I call a power district but is in effect an isolation section. This works quite well and your colour scheme would fit this concept quite well with some revision to take care of the reverse loops included in the design.
 
Greg Elmassian

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Actually feeding each end of an isolated section is the same voltage drop as feeding the center and it's half the wire. Think about the max distance from the feeder.

In dcc this is a bad idea (feeding each end) as you actually will distort the signal more too.

Greg
 
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dunnyrail

dunnyrail

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My idea is that if any joint looses power you get a feed from the other end. As for distorting the signal ...... never been a problem for me.
 
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Greg Elmassian

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Yes, it helps that situation, BUT it causes other problems, first, isolating the bad joint becomes much harder, you really will have to disconnect one of the feeds to find the bad joiner easily. Many people operate layouts with poor conductivity, but have it masked with schemes like this. What happens is when you get a second bad point of conductivity? now you have 2 bad joints and it is VERY hard to locate them. Now you ABSOLUTELY have to start disconnecting wires. Sort of delaying going to the dentist and instead of fixing a cavity, now you have to pull the tooth. Did you benefit in the long run? No.

Second, you use twice as much feeder wire, wasteful and money better spent on rail clamps, home run vs. daisy chaining, or heavier gauge wire, etc. There's tons more reasons, but these are the fundamentals of why feeding an isolated section from both ends.

I've studied the people who have "given up" on track power, as being too hard to maintain. Making the debugging of problems too difficult is one of the primary factors, and this is why I am so vocal on the techniques to keep maintenance and debugging SIMPLE.

OK, when you say distortion never has been a problem for you, that is great, but recommendations to someone new should be as "bullet proof" as possible, and the chances for distortion outdoors is great. Many times there are runaways, slow response times, and the user blames it on the decoder, or installation, or command station, when just poor practices were followed when constructing the layout. You should read the issues large HO layouts have, and realize that our longer (in feet) runs of wire and track and being outside in the elements put additional challenges to the setup.

trackwork, conductivity and power feeds are all the foundation of a track powered layout. Get it right, and years of trouble free and low maintenance enjoyment is yours. Get it wrong and it makes people miserable. (and give up or go battery).

On the other hand, the number of people who violently espouse battery as so much better than track power is high, and I ask everyone I meet (we have a large club and I get hundreds of emails a year) about the issues they had with track power. Almost all of them were poor practices, or a misunderstanding on how you can get distortion or other problems on track power and DCC.

So, I strive to give newcomers the best advice to have the most success and minimize debugging issues that they really do not need to encounter. This is why I am coming back persistently, not to argue with you but to help people starting out.

Greg
 
Diesel2000

Diesel2000

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I agree with Greg - if you are running DCC on your line it makes absolutely no sense to run separate power for turnout decoders scattered all over the place. The power draw of a turnout motor is minimal and only momentary. You are very unlikely to throw more one at a time. Even two will require only one amp or less. And, again it's only momentary. Each decoder itself typically draws less than 50 milliamps continuous which is insignificant. The single greatest advantage of DCC is eliminating tons of wiring while still being able to run multiple trains. This is a huge bonus outdoors. Take advantage of it! Connect your turnout decoders to the track wherever it is most convenient.

From experience I also second Greg's recommendation that you have separate isolated track districts wired as a star rather than a loop. However, unlike analog control you do not need a bunch of them. Between two and four are probably all that are required depending on the layout complexity. Concentrate on multiple solid power connections to each district and keep each run as short as possible. This will ensure you have hardly any voltage drop and more importantly a clean DCC signal to all your decoder equipped devices. You can initially power the layout with a single booster at the source. Then, in the future if you think more power is required, you can supply each district or groups of districts with their own booster.

Thanks for the feedback. For my yard configuration I plan to use switch routes and therefore will be throwing several simultaneously. In testing single EPL drives on my Massoth CS I found they were consuming roughly 1 amp each. I also decided to go with the 4 channel Massoth switch decoders for $ consideration (4 at $75 each vs 16 at $45). I do not plan on having any buildings or structures to locate these in outside, so thats why having a separate switch power bus seemed to make sense. A Tam Valley booster and 24v 5amp power block were $65 so its pretty economical to add that and then never have to worry about it again. To fully isolate from shorts shutting down switching I would still have to wire the decoders prior to the circuit breakers, so I dont see it saving much wiring over just put it all on it own bus at this point. Due to the slight grade on part of the layout I've measured a single new loco at 2.5 amps. I may have up to 4 locos running at a time, so this way I dont have to worry about power.

Originally I was going to install weatherproof enclosures for the decoders and circuit breakers and have all the wiring running from the south end of the layout (which is why i asked about daisy-chaining the mainline connections), but after thinking about it over the weekend I've come to realize that I could easily locate everything in the house towards the middle of the 2 loops by the yard, which would shorten all wire runs to what I have now. The layout runs along the side of the house with a patio/grill area at the south end.
 
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Greg Elmassian

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If you use the epl drives, they only consume power when moving right? I was more asking about the current drawn by the decoder in steady state.

So, I don't see why you would want a separate power bus still... yes there is a negative side, a short will remove power from the decoder, but so what? The switch won't move. And the short will only affect switches in that power district.

Just thinking of reducing the wires running everywhere, locate the switch decoders as close to the switches as possible and run power from the rails, is my suggestion.

I would likewise locate the autoreverser(s) where they are needed and thus keep the wires as short as possible, this helps in determining shorts.

Greg
 
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Diesel2000

Diesel2000

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If you use the epl drives, they only consume power when moving right? I was more asking about the current drawn by the decoder in steady state.

So, I don't see why you would want a separate power bus still... yes there is a negative side, a short will remove power from the decoder, but so what? The switch won't move. And the short will only affect switches in that power district.

Just thinking of reducing the wires running everywhere, locate the switch decoders as close to the switches as possible and run power from the rails, is my suggestion.

I would likewise locate the autoreverser(s) where they are needed and thus keep the wires as short as possible, this helps in determining shorts.

Greg
Both the 4 channel and single channel Massoth decoders appear to draw 30mamps, so not a big deal overall. The EPLs only draw power while being thrown.

Given the design of the 4 channel decoders I dont really have anywhere to locate them around the layout without having to install weatherproof enclosures of some kind either all in 1 place or in multiple locations around the layout. I live in the midwest where we get everything from sub-zero temps to 95+ plus degrees and humidity with rain, sleet, snow, and everything in between. By locating them in the house I dont have to bother with any of that, I'll just have to run a bit more wire, which seems like any easy trade-off. Where they get their power at that point wont matter as the decoders will be located by the other power equipment.
 
Greg Elmassian

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Good, we are now on the same page for current draw from the main line. Do the Massoth decoders allow separate power and DCC feed? I thought they were combined. Are you thinking of a separate booster running the decoders? I really think no matter where they go, I would run from the main track power.

Right, I agree the issues is weatherproof enclosures in multiple places. I use the gray plastic conduit junction boxes, designed for outdoor use. Easy and cheap, with a weatherproof gasket.

I don't think it is so much work, vs. I would say a lot more wire, but it is definitely your tradeoff to make.

In any case, sounds like you have it figured out, I just try for fewer and shorter wires, seems to result in lower maintenance, but heck, my switches are all pneumatic anyway!

Greg