I'm slowly pulling together the info I need to get rolling on my layout-managed to get about 10 feet of the benchwork up today. My plans are for a HOn3-mountains and mining, 4 level helix, with the yard area and roundhouse being the focal point. The layout is around 3 walls 30-36" wide with a 4'x8' pennisula off one end, about 50 feet long and about 250' of track. My primary interest is building rather than prototype operations. I'm planning on getting the Digitrax Super Chief 5 amp with radio. I'm comfortable with woodworking, mechanical and electrical stuff--electronics and computers scare the daylights out of me.
I've already bought the Blackstone K-27 so I'm committed and determined to learn this stuff. Oh--there's no LHS within 70 miles and of the 5 within that radius, only two speak DCC but they don't like narrow gauge--HELP!!! I've picked up the idea that accessory items are run off dc--does that mean another set of bus wires and power source? What size wire? I have a relatively large supply of 14 and 10 AWG romex w/o grnd that I'd like to use up on the layout. My research shows that 14 AWG would be just barely ample for the DCC buses--if I use the 10 AWG, will I lessen the need for additional power supplies and boosters? Do the boosters have to be wired to the command station? What kind of wire/cable?
These seem like basic questions, but I have tried to find this info on my own through the internet and I bought the book DCC Made Easy but no answers. Please help! Thanks, Steve
Some additional basic questions that would help better plan your wiring. How may trains do you expect to be running at once? ANd how many operators?
While the 5 amps might be enough for the total number of traisn you'll be running, you might want both a second booster and a couple of devices known as DCC circuit breakers to divide the layout up into 'power districts'. When you do that, a derailment or short in one section won't shut off the whole layout. Think of them as large DC blocks. With a 50' overall layout length, you'll either want to put the one booster/command station in the middle, making the longest power bus run 25 feet, or if you go for the second one (with Digitrax components, a DB150 - a second DCS100 is both expensive and unecessary unless you want to have a spare) put one about 13 feet from oen and and the other 13 feet fromt he other end - so about 12.5 feet or heavy wiring in each direction from any power source. The shorter you can run the heavy wires, the less voltage drop there will be - thus placing the booster to minimize the wire run.
If you are going to add stationary decoders to operate switch machines - they should have their own power bus, at the very least run through one of the circuit breakers, independent of any track. Why? Well, if the switch motor is powered from the same place as the local track power, and you create a short by accidently running into a turnout set against your train - the power will be off. The power to the track AND the switch machine decoder, so you won't be able to throw the turnout and 'unlock' it. If the switch decoder gets power from a seperate power feed on another breaker, it wil still be active even though the loco has shorted out the track power.
If you have even a simplified diagram of the layout shape and approximate track location, we can give you more detailied information as to exactly where to run the track buses.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Oh, and if you arrange the booster(s) to minimize the length of the bus, #12 wire would eb sufficient. HOWEVER, if you already have a bunch of #10 available - by all means use it, rather than buy even more wire. You can run longer runs with equal drop compared to #12, but putting the booster at one end and having over 50 feet of wire is not a good idea, even with #10. Remember you need a complete circuit, so that's 100 feet of wire - even #10 will show measurable drop over that distance. Definitely don't use the #14 for any runs over 10 feet. You might want to run the #10 and have terminal strips in key locations, and pull off some #14 to go to nearby related track feeders. This extra step will give you a place to 'cut in' track detection if int he future you want to add detection and signalling.
All non-DCC accessories, like structure lighting, should have its own powe rsupply independent of the DCC system. DCC boosters are too expensive to provide a steady voltage to light up a town full of light bulbs.
The one thing that caught my eye has nothing to do with wiring. Don't make your around-the-wall benchwork any wider than 30 inches. That is generally considered the maximum "reach distance" for accomplishing anything once there is other stuff on the layout in front of it. I've got a 5 foot wide table, so the center is 30 inches from the edges. It's a stretch to do things in the middle of my layout.
It takes an iron man to play with a toy iron horse.
Thanks for the quick responce, Randy. I knew that a track plan would be requested--I ain't got one--it's all in my head and it's kinda fuzzy. I'll try to scratch out something and find time for my wife to put it on the site for me. I don't think that I'll ever have more than 6 or 7 locos unless we get a fleet of galloping geese running and I doubt more than 2 or 3 will run at any one time (is it possible to run more than one on the same throttle at the same time?).
The layout is U-shaped against the 3 walls-12'x15'x11' with the 4x8 yard area coming off the 12' leg toward the middle. The helix is in the corner at the other end of the 12' leg so most of the trackwork is toward one end. The other two legs will be a main line out and back with a mine complex and a town of some kind. Steve
MrB-Been there-done that-- but I had to widen a 6 foot section to accommodate a custom built section of ten drawers that fit under the table and it is a reach--and I'm almost 6' tall. Steve
rrinkerRemember you need a complete circuit, so that's 100 feet of wire.
Remember you need a complete circuit, so that's 100 feet of wire.
What do you mean by this? Generally your feeder bus does not have to return to itself. it can be left disconnected (but isolate from the other wire) at the end of the bus. Why would you need the extra 50 Feet of wire? From what i have learned you do not want to connect it back to itself because then you have just created a giant UHF Antenna and it will cause interference.
Thanks
Renegade
Colorado Front Range Railroad: http://www.coloradofrontrangerr.com/
The bus is a 2-wire thing, not a 1-wire thing. By "complete circuit" he's referring to the 2 wires, so a 50-foot run requires 100 feet of wire. Of course, if you're using 2-conductor cable, then you only need 50 feet of it, but it's still got 100 feet of wire in the run.
You're right about connecting the ends of the bus, though. The recommended practice is to dead-end them, not loop them back on themselves. That goes for your DCC command bus, too.
Exactly - the only place you want the two wires connected together is through a decoder on the loco sitting on the tracks. Any place where the two bus wires would touch would be a short . But the current has to go ut 50 feet, power the loco, and then return that 50 feet - there's where the 100 feet comes in. OK, technically it's flipping at a fairly high rate but the whole concept is the same, if the furthest point in the wiring is 50 feet fromt he power source, the current has to travel 100 feet for a complete circuit. Smaller example,my layout was 8x12 overall, made up of 2' wide sections - a big donut. My track but wires started in the middle of one 12' side and ended in the middle of the opposite 12' side - NOT connected to one another - viewed from the top, the wires were like a C that was almost but not quite closed. Small layout can be deceiving - that was 15-20 feet of wire per side, 20 if I followed the outside edge of the benchwork but since it was in the middle it was closer to 15. That's distance from the power source - with 15 feet of distance the electricity has to travel 30 feet. So for the doubters - #12 wire here was NOT overkill.
The DT400 throttle in the Super Chief set can control 2 locos at the same time - there are two knobs. With a max of 6-7 locos running, if they are relatively modern ones (not old brass with 1 amp motors) you're probably ok with 5 amps of power, however I'm still mullign over the description of the room and you might need more than one booster just because of the distances involved. It's a lot easier to string a length 6-conductor flat phone wire (which you will have anyway, connecting the jacks for throttles along the edge of the layout) than a bunch of heavy power wire. You probably will want multiple power districts with multipeloperators runnign trains - sudden stops can be downright disasterous depending where your train is at the time, not to mention just plain annoying, especially when you're just driving your train and the sudden stop is because you buddy on the other side of the layout messed up. On the other hand, if everyone's trains stop, there's no hiding the mistake for the one who made it.
ahh ok. the 2 wire part was unclear. when someone says bus wire. i assume two wires. so I was thinking that he was talking about 100 feet of each wire.
I got a track diagram, scanned it, but can't get it on this forum--what public domain is being used to load to this site? Steve
i use photobucket to upload my images and post them to the forum, but there are several other hosting sites out there.
Here's photo of the hand drawn layout --in case it's not clear enough, some details on the helix--20" radius, 4 level with 2.4% grade. That figures out to be about 10 feet per level or about 40 feet of track. I'm thinking about running 14AWG up the perimeter of the helix in at least two if not three locations around the circumference to pick up the feeders to the track and some form of isolating the entire helix track system.
OK, looking a tth epicture, I would probably run 2 boosters. The DCS100 in your Chief set, plus a DB150 configured to be a booster only. Put one under the layout near the helix, on the yard side. Use at least two circuit breakers, one for the helix and one for the yard area. If you use a Digitrax PM42, you can wire one of the 4 sections as an auto-reverse and connect that to your turntable - not need to flip a toggle to turn a loco around. Put the other booster over near the corner opposite the helix, to power the right and top areas. Same thing with circuit breakers, and the turntable on that side.
For the helix, don;t run the wires along the perimeter. Run 2 or 3 sets of #14 wire stright up the inside edge of the helix, evenly spaced. Run feeders off the track on each level where the wire goes past. Underneath the helix, tie all the #14's together and run to one of the breaker outputs with your #10, unless the breaker is right there under the helix. Most circuit boards won;t have terminals that can connect directly to #10 wire - usually #12 is about the biggest, so you'll probably have to run a short section of smaller wire from the breaker to a large enough terminal strip to attach the heavy wire to. As long as the smaller size wire is kept to a minimum, it will be ok. Run 3 more #10 wires down towards the yard. One near the rear to power the yard tracks, one down the front to power the main line, and one fromt he section configured to be the autoreverse to the turntable. On the other side, divide the mainline loop into 3 sections, from the helix around to the wall side near the helix. Probably 3 equal sections depening on how much activity will be in various areas of track.Run lengths of #10 near these tracks to attach the feeders to. Run another #10 down to the bottom right turntable - also connected to a section of the breaker configured for autoreverse.
That's just one way of doing it. There are certainly other workable and reliable ways to do it. I definitely think it's too big to just one run booster and one set of #10 bus wires all around the entire room.
when using #12 in a house its good for say 15 -20 amps from the basement to second floor which could be more than fifty foot on a circuit so why not good enough for whole train layout or am I missing something else
gjvjr50 when using #12 in a house its good for say 15 -20 amps from the basement to second floor which could be more than fifty foot on a circuit so why not good enough for whole train layout or am I missing something else
In a house circuit the limitation is all about heat, and fire danger. In a DCC bus, it's all about voltage loss, and signal integrity. So, it's pretty much apples and oranges to try to compare the usages.
Jeff But it's a dry heat!
Yes - with a 120V feed your device at the other end can still work with getting 110 volts - a 10 volt drop is nothing. Loosing even 2 volts of your 14 volt track bus will result in a noticeable speed drop in a loco. You want to keep voltage drop to 1 volt or less maximum. #12 wire has a resistance of almost 1.6 ohms per 1000 feet. That/s 0.0016 ohms per foot. Say you run that wire 50 feet. That's 100 feet of wire, out and back. 0.16 ohms total resistance. Ohm's law says voltage is equal to current times resistance. So say you have a 3 amp load at the end of that. About a half volt drop - probably ok. If you have an 8 amp booster and the full load at the other end, it's more like 1.3 volts - probably noticeable in loco speed.
#14 wire is 2.5 ohms per 1000 ft. So in the above example, with the 50 foot run, #14 wire would have 3/4 of a volt drop - maybe ok. But a full 8 amp load at the far end would be 2 volts of drop - definitely too much.
The price difference between #12 and #14 isn't that much, at least when you buy big spools of it. Unless you have a very small layout, don't bother with smaller wire other than for short feeder runs (since it's not really possible to solder #12 wire to HO track and have it still work as track). Distances add up faster than you think. My last layout was an 8x12 'donut' shape. Running a bus wire around near the outside edge of even that relatively small layout would be 30' of run length, 60 feet of wire! Around 3 walls of a 12x15 room (2 on the 15' dimension) would be a 42 foot run length, 84 feet of wire.
There is an alternative to larger wire. Just add a booster power district when the voltage drop gets around 1 volt. Of course heavier wire is much cheaper than a booster and power supply.
Martin Myers
mfm37 There is an alternative to larger wire. Just add a booster power district when the voltage drop gets around 1 volt. Of course heavier wire is much cheaper than a booster and power supply. Martin Myers
Yes, although at some point it gets impractical to keep using bigger and bigger wire and you have no choice. A huge 20x40 layout would probably need multiple boosters even if you only ever ran one train with double headed locos on it.
Randy and others--Thank you for the time and effort you put into my question. My head is kind of spinning but it's starting to make a little more sense to me. I need more research on the physical properties of the various devices. I had thought that the Super Chief was the middle system of the Digitraxx line, but now its looks to be the top of the line??
Randy-in one of your posts, you mentioned the 6 wire phone cable--is that required to communicate between the boosters only or does it go to the throttles as well (remember, I'm going to have the radio throttle). Thanks, Steve
Hello.
Digitrax sells the Zephyr that is the runt of the litter. Next up is the Empire Builder... the middle sibling. Unable to read locos but good for boosting. And finally, the Super Chief is the top of the heap.
Your 6 wire cable is known as the "Loconet" in digitrax. That is necessary to communicate commands from the command station, to your panels where you connect the DT400 throttle either via radio or plug in.
Digitrax has radio availible. With the correct panels with antennas you can communicate to the command station.
DONT confuse your command station (DCS 100 or whatever) with a second station (OR several more) which is called a BOOSTER wired to provide slave power to a specific part of your railroad.
Also the loconet provides a platform to communicate to the extra booster or to switch machines or even to the signalling and in extreme cases to your personal computer via JMRI. But let's not worry about all of that now.
I have a small industrial branch. A loop of track in a 12 by 8 room. I would run 12 gauge about 10 feet from command station to a big power distribution board. Then run from that PDB to 4 PDB's equally spaced around the walls of the room. Each PDB is probably 10 feet away from the first one.
All track feeders in each of the 4 sections of the rectangles feed off the PDB's in my scheme.
My kato switches run off the Digitrax DS 64's which are connected to the Loconet (Your 6 wire cable) however the DS64's are connected to the house via thier own power plugs.
Each of the 5 PDB's present in my plan will recieve a local circut breaker. My train room will recieve a fast Ground Fault plug in the wall. Finally my Digitrax power supply plus the command station are all good fast protection.
I have somewhat over-engineered my electrical. I retain the ability to move into O gauge with it's greater power any time in the future when vision finally goes too bad for HO.
Finally I use color coding. Kato track for me gives me blue and white feeders tracks. I mark the underside of the track white rail, blue rail. If you drew a circle of track on a peice of paper. Stick a pole in the middle of that circle. Call it north pole. Suddenly your outside loop rail track is south rail and your inside loop track rail is the north rail.
I need to keep all the rails facing the right way (If that makes sense) towards that center north pole in my room so that there is no conflicts in the power anywhere. I dont run turntables or reverse loops.
Back to color coding. The switch machines have red and black wire to the DS64's
That means my bus wires will need to be something like Blue/Yellow or something like that. That way i can look under the layout at any time and instantly recognize which pairs of wires are doing what.
Finally but not last, I pernamantly marker the underside of every track feeder... such as "West Run around track feeder" or... "West Mainline feeder" Refering to the tracks on west wall of the room.
Stranded wire is better than solid wire in my opinion. The bigger you go like the 10 gauge or 12 gauge is better for you.
Your layout is a monster compared to mine. But my house has wiring carrying up to 12 amps like 50 feet to a plug and thence across a 10 gauge extension cord 150 MORE feet to feed my 12 amp chainsaw at times outside. That is way way way more power and danger than we will ever see down here in the 12 volts or whatever.
I cannot hope to run a 12 volt engine 200 feet outside of the home because there is just simply too much metal in the wire all the way to the choo choo. But I can load it with 120 VOLTS and make that chain saw growl across that mass of metal.
Finally but not last, 100 feet of wire is about what you can do with a Binary signal from your command station to a DCC decoder onboard your engine. After 100 feet, the signal starts to break up and the engine is hearing impaired unable to clearly understand commands.
First the Chief (DT100 throttle), then the Chief II (DT300 throttle), and now the Super CHief (DT400 throttle) have always been the top of the line systems. The Empire Builder series has been the middle of the road, until the Zephyr was introduced. Given features like CV readback and a dedicated programming track, I put the Zephyr ahead of the Super Empire Builder. A Zephyr plus a DT400 outdoes the Super Empire Builder in every feature except absolute power, the Zephyr being 2.5 amps vs the 5 amps of the SEB.
I agree. #14 is overkill for model railroading applicatons but we use it 'cause it is the standard size for house wire and thus readily available. According to the wire table #14 wire has a resistance of 0.2525 ohms per 100 feet. If all the current of a five amp booster went the full distance (no locomotives nearer than 100 feet) then the voltage drop might be 1.26 volts, which is nothing to worry about.
I avoid wire heavier than #14 because it is very stiff and hard to bend around terminal lugs and such.
David Starr www.newsnorthwoods.blogspot.com
dstarr. If all the current of a five amp booster went the full distance (no locomotives nearer than 100 feet) then the voltage drop might be 1.26 volts, which is nothing to worry about.
Actually, while we were running btests for the NTRAK wiring RP adopted in 2005, we found that a voltage drop of more than 1 volt could lead to DCC signal degradation. The RP uses 12awg cable. We decided it was simpler to have it than to need it.
"signal degradation"? Does that mean failure of the locomotive to respond to commands? Or does it mean 1 signal packet out of 10,000 packets is missed?
I don't do DCC, so maybe it is more tender than it ought to be. I have done RS-232, RS-422, IEEE 488, modbus, and USB. All of those worked just fine with a 10% voltage drop. I used to test digital signal processors. We required the DSP to operate properly and pass diagnostic tests with the power supply both 10% high and 10% low. I'd expect a DCC decoder to do as well, and work properly with track signal 10% low.
It's not so much an absolute signal level issue as it is quality, I think. Many decoders are designed to work on anywhere from 12 to 22 volts! That's a HUGE range. Over what can be a rather unreliable transmisison medium - track to wheels. With longer bus runs and loads, you can start to get some serious ringing in the signal, and it seems to easily confuse the decodersI don't think the signal sepration in DCC decoders is very sophisticated - perhaps an area of improvement in the future, or to distiguish a more 'premium' decoder for lesser ones. However, it's not a problem for the majority of people running DCC, even large modular layouts, so there is probably no reason to increase cost with more sophisticated signal detection circuits.
dstarr "signal degradation"? Does that mean failure of the locomotive to respond to commands? Or does it mean 1 signal packet out of 10,000 packets is missed?
It means failure of the locomotive to respond. Also the frequency of runaways increased. I mentioned that that limit was part of tests for NTRAK. We run at 12 volts so 1 volt is an 8.33% drop. Tests were done using a 3 amp load with relatively new or new connectors on our modular bus lines. 1 volt drop became the absolute maximum as we know that wear and tear, different levels of skill, increased current draw,etc. would come to play as well. The idea was also to decrease the number of expensive booster/power supply combos needed for large layouts. Wire is much cheaper. Power Districts that need to be shortened won't suffer either. As a bonus, we've found that our analog DC operations have improved as well and even had to turn down our DC power supplies that had been turned up to 14 volts to overcome voltage drop. We were burning out 12 volt indicator lamps with the heavier wire.