thanks to every one for the great information.I'm sure I'm not the only dcc beginner benefiting form the information. thanks again.
Oh yes, as for the 'properly balanced output'. I agree. But as soon as you hook that up to track and gap the division, you introduce possible issues. There's always potential for the two gaps to NOT be crossed at exactly the same time. This creates the common rail situation, with the first gap being bridged becoming the common rail. Granted, this is starting to get out there on the fringe and is probably not something to lose sleep over. It is probably more an issue with a steam loco with offset pickup, or a diesel with the old 4 wheel pickup instead of 8 wheel. You introduce a common rail with the metal wheel across the gap and have a current path via the motor. Or more accurately the decoder - witht he potential for double track voltage.
Now, either a) this is not a big issue because we don't hear about people with large multi-booster layouts blowing decoders on a regular basis or b) it's not a big issue even though it does happen constantly because it is for such a short time period that it takes years or more of this happening to actually damage a decoder.
Bototm line, I'd still hook up a heavy ground wire between boosters, and also to any PM42's being used. And still not connect the system to earth ground, and always use an SELV power supply so the low voltage site is isolated from the house wiring side. And as convenient as it might seem, i think I would refrain from runnign any house current wiring along the layout. Yeah it might be convenient to have some outlets along the front edge of the layout, but with narrow benchwork is it really that hard to reach a wall outlet? Also makes it pretty much imposisble to drill through a live 120VAC line while installing a turnout throwbar, or having a connection come loose and 120VAC applied to the track or something else you expect only safe low voltages. I realize in some cases this isn;t completely practical - such as lighting for the lower deck of a double deck layout - just be careful!
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
mfm37 What would it hurt to run a larger wire? Pins 2 and 5 are tied to the Ground terminal and the metal case already. With a loconet cable, the connection already exists. It is my understanding that the more robust ground (common) may be needed in the case of a reverse loop short circuit. Martin Myers
What would it hurt to run a larger wire? Pins 2 and 5 are tied to the Ground terminal and the metal case already. With a loconet cable, the connection already exists. It is my understanding that the more robust ground (common) may be needed in the case of a reverse loop short circuit.
Martin Myers
Nothing. The recommendation for between boosters is actually to pull out the ground pins from the RJ12 connectors and use the heavier wire.
Another thing they don't tell you inthe manual, but when you use an auxiliary power supply for the UP5 panels, if you daisy chain a coupel per power supply as they say you can do, there's one reasonably robust wire carrying one side of the current and the other side goes over - those thin phone wires int eh Loconet cable! I haven't built big enough to need it yet, one of these day I'll have a basement again, and when I do the extra power will be supplied to the UP panels with a plug that plugs in where the power supply plugs in - no relying on the thin phone cord although given that the throttles don;t draw THAT much power it's probably no big deal. I think it's more of an issue if you use somethign bigger than the PS12 and supply many or all panels form a single power supply - which is entirely possible. But then if you have 10 throttle plugged in downstream of the first powered panel, that ends up being significant current on the little phone wires.
Another bit about the ground wire - you are also supposed to hook that up to PM42's. I'm sure there is some reference between the rail connections and that ground. I've seen reports where peopel had problems with using PM42's as reversers - and when they hooke dup the groudn wire that hsould have been there all along it started working. Although the AR1 does not use a ground wire. Soon as I get new equipment I'll pop the lid and take a careful look at the circuit layout and see just what's up. I think I had the cover off my first Zephyr before I even hooked it up to trains - I'm like that with gadgets.
rrinker If you use the recommended power supplies, there is NO connection to the house ground. There is no ground connection in the PS515. This too has been discussed many times and the idea is to NOT connect your layout to the house wiring at any point for any reason. Not needed, and not safe if you have an outlet wired backwards. And for the very reason you listed - another good one why you should NOT connect that ground terminal to the AC house ground. Want proof the ground teminal IS referenced by both sides of the output H bridge in the booster? Just look at the recommended way to check track voltage if you don't have a fancy meter that can handle the variable frequency square wave: Test from Rail A to GROUND and test from Rail B to GROUND and add them up. If the ground terminal was only connected to the booster case and maybe the Loconet ground wires but not part of the power circuit you couldn't do that. Digitrax even lists this procedure in an app note for measuring track voltage. As for the opto-isolation, as far as I know it's still an option from Digitrax. It's not really needed if you don't use common rail wiring, which you shouldn't. This link has a lot of interestign tidbits. http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000hqP --Randy
If you use the recommended power supplies, there is NO connection to the house ground. There is no ground connection in the PS515. This too has been discussed many times and the idea is to NOT connect your layout to the house wiring at any point for any reason. Not needed, and not safe if you have an outlet wired backwards. And for the very reason you listed - another good one why you should NOT connect that ground terminal to the AC house ground.
Want proof the ground teminal IS referenced by both sides of the output H bridge in the booster? Just look at the recommended way to check track voltage if you don't have a fancy meter that can handle the variable frequency square wave: Test from Rail A to GROUND and test from Rail B to GROUND and add them up. If the ground terminal was only connected to the booster case and maybe the Loconet ground wires but not part of the power circuit you couldn't do that. Digitrax even lists this procedure in an app note for measuring track voltage.
As for the opto-isolation, as far as I know it's still an option from Digitrax. It's not really needed if you don't use common rail wiring, which you shouldn't.
This link has a lot of interestign tidbits. http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000hqP
The URL above talks mostly about common rail wiring, which basically takes the balanced differential outputs and makes them common to a rail (thus creating an artifical reference) and you no longer have a balanced output. Digitrax recommends optical isolated boosters for this to avoid feedback problems due to an unbalanced condition.
From page 22 of the Super Empire manual:
4.1 Direct Home Wiring vs. Common Rail Wiring
Digitrax strongly recommends direct home wiring where each power district and its booster are electrically isolated. This type of wiring is safer and more convenient to work with for debugging and for adding reversing sections and detection later.
I am not saying there is no reference to ground. I am saying that with a properly balanced differential output the ground reference is not used for the output and all power flows across the balanced leads. If any of it ran to ground the output would become unbalanced and you'd have all kinds of problems develop. If ground were really needed (because one half of the output needed something the other half didn't) then you'd see three wire tranmsission and there would be some current to ground. Pull your ground leads off and things still work.
Now one example could be if the outputs are not properly balanced from the boosters themselves (not due to a load condition). In that scenario it is possible to have one side (A or B) flowing some current to ground or through the other booster. In that case the current to ground flow is generally a better option than through the other booster, since the additional unbalanced current flow condition may overload the other booster. This is hard to determine without seeing the internal design of the boosters.
After looking again at the Digitrax power supplies, I agree they do not have a ground connector for the low voltage output. So, I must assume then that they do not expect the ground leads on the boosters to be any type of safety ground. I'll eat a little crow on this and say if the ground pins aren't connected to a safety ground then I don't see any downside of connecting them all together as a common reference but I also don't see the need either.
I'd like to see more information from Digitrax on this. I've never seen a balanced transmision system require a common ground reference. It's a contradiction in terms.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
rrinker Especially important to run that heavy ground wire if oen of the downstream boosters is used as an auto-reverser. The ground is the reference and as a train crosses the gaps, full track current will flow through the ground wire briefly, until the booster reverses. Now, do you want that in 28ga phone cord or a piece of 14ga wire? --Randy
Especially important to run that heavy ground wire if oen of the downstream boosters is used as an auto-reverser. The ground is the reference and as a train crosses the gaps, full track current will flow through the ground wire briefly, until the booster reverses. Now, do you want that in 28ga phone cord or a piece of 14ga wire?
Randy,
I am not buying this for many reasons. I'll just point out two to start with and then I'll need some pretty hard data to show why this is needed.
1. The DCC outputs are a differential balanced output and thus do not have a commonn ground reference. Their reference is each other (i.e. differential voltage between A and B). The "short" you describe should be between A of one booster and B of the other, with the return back through the other lead. Not through any common ground or Loconet. If so, there is a problem. In fact the new 8A boosters are optically isolated between Loconet and the outputs, making this impossible.
2. From a safety perspective the ground on the boosters is an AC protection ground back through the power supply to your AC outlet. Thus if you plug in all of your booster power supplies to a properly grounded 3 prong outlet and then wire them again together on the front of the booster with another piece of wire, you have setup a possible safety issue. If one of the three pronged AC outlets ever loses its ground lead you now have your AC safety ground running from one booster to another and then to the AC outlet ground that still exists. Not an ideal situation.
I have other reasons than just these but these are the two major ones. I've seen other folks also post what you are saying but I'll want to see the manufacturer back this up.
mfm37 jbinkley60Ditto on my DB150 but not the DB200+. Digitrax shipped a bunch of the DB150s with A/B backwards. I think it may be a crap shoot on the orientation of the A and B outputs. It's probably more to do with railsync orientation. My club ordered two DCS200's on the same day. Both came directly from Digitrax in the same order. To this day one unit's outputs are reversed to the other. I've tried making one unit an auto reverser and shorting it one time to correct the outputs. That works but as soon as the unit is reset to defaults, it reverts to its original out of phase condition. I've installed a DPDT reversing switch on its outputs. We just flip the switch to correct phase problems now. Martin Myers
jbinkley60Ditto on my DB150 but not the DB200+. Digitrax shipped a bunch of the DB150s with A/B backwards.
I think it may be a crap shoot on the orientation of the A and B outputs. It's probably more to do with railsync orientation.
My club ordered two DCS200's on the same day. Both came directly from Digitrax in the same order. To this day one unit's outputs are reversed to the other. I've tried making one unit an auto reverser and shorting it one time to correct the outputs. That works but as soon as the unit is reset to defaults, it reverts to its original out of phase condition. I've installed a DPDT reversing switch on its outputs. We just flip the switch to correct phase problems now.
I dug around on Digitrax's site and found this. It explains things pretty well.
http://www.digitrax.com/kb/index.php?a=865
DCS100 and Boosters I recently split my layout in half, with a DB150 acting as a booster powering one side and a DCS100 powering the other. I'm trying to reconnect the bus feeders to the rails, which all worked properly before the split. Now when I reconnect the feeders there is no short indication, BUT when a loco goes over the insulated gap between the two sections, a short occurs.This is a known issue, a common occurrence when a modeler adds their first booster to a DCS100 command station. MOST DCS100 rail connections are the opposite phase from the DB100 and DB150 boosters, thus Rail A on a DCS is the same phase as Rail B on a DB. A short occurs when a locomotive passes from one phase to the other. The easiest solution is to simply reverse the Rail A and Rail B wires connected to the DB150; you can also set the Booster to auto-reverse to reverse it's phase:To set up DB150 for autoreversing:1. Start with an un-powered DB150.2. Connect the DB150‘s CONFIG A, CONFIG B & GROUND terminals with two short lengths of wire.3. Set the DB150’s MODE switch to RUN .4. Power up the DB150. The DB150 will automatically convert to automatic reversing booster operation when you power it up.5. Connect to other DB150s on LocoNet via either LocoNet Jack A or B using LocoNet cables that have been tested with an LT1.
As for the 'flipped' rail connections - they did indeed make soem that way. I don't knwo if enyone has opened them up to see if what got flipped was the two output wires from the power transistors or the railsync likes on the loconet connectors. Whichever it is - if it's flipped and you aren't doing auto reversing, it's going to STAY flipped. If it goes back and forth as changes are made to your system, you have mixed in with the Loconet cables one or more wired as 'phone' cords instead of 'data' cords, which is another culprit for flipping the booster output as a crossover 'phone' cored will reverse the phase of the railsync lines. Even if you have exactly two boosters and one cable - check to make sure the cable is wired properly before assuming you got a flipped booster. This is one place where the properly wired cable DOES matter.
simon1966Look at page 24 in the PDF link http://www.digitrax.com/ftp/superempire.pdf
It's good practice to add a 14awg ground wire between boosters and the command station ground terminals. Depending on the 28ga wires in the loconet cable could bite you.
simon1966 locoworksand if you get a short running from one power district to the next, change the rail out leads on the DB150. This is exactly what happened to me when I added an Empire Builder Set to my existing command station. Instant dead short as soon as a loco hit the gaps between the power districts. Turned out that the DB150 had its A and B rail outputs reversed with respect to the other command station.
locoworksand if you get a short running from one power district to the next, change the rail out leads on the DB150.
This is exactly what happened to me when I added an Empire Builder Set to my existing command station. Instant dead short as soon as a loco hit the gaps between the power districts. Turned out that the DB150 had its A and B rail outputs reversed with respect to the other command station.
Ditto on my DB150 but not the DB200+. Digitrax shipped a bunch of the DB150s with A/B backwards.
Yeah, just get a small power supply and a piece of track and use the PR3 as a standalone programmer - even that does more than using a DB150 to program through. And JMRI works with the PR3 in standalone mode too.
When I took my initial plunge in to DCC I bought a Digitrax Super Chief Radio (DCS100) with a DT-100R throttle and UR-91; and a regular Empire Builder (DB150) with a DT-100 throttle and UP-3 as it was the best way to go. I have since picked up another DB150 on ebay.
I use Decoder Pro with an MS-100 for programing through my DCS100 on the home layout.
I am currently using one of my DB150 as a command station and a new Digitrax PR3. (I am away from home and have some of my locomotives with me to add decoders). I am also going to try the PR3 alone as it is difficult to go back to programing through a DB150 when I have used the full features of the DCS100 all of these years.
My point is to go with a Chief (DCS100) if you can afford it as the additional features will pay off in the long run.
Jim, Modeling the Kansas City Southern Lines in HO scale.
Hi!
Thank you Simon for the reference - it sure does explain how to wire in the second booster.
Thanks,
Mobilman44
ENJOY !
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
I cannot answer your question but there is a very active Yahoo Digitrax DCC Group I belong to.
http://groups.yahoo.com/group/Digitrax/
There is quite a lot of info in the Files and Photos section of the group.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Sure does.
Look at page 24 in the PDF link http://www.digitrax.com/ftp/superempire.pdf
There is a ton of good support info on the Digitrax Tech support depot pages.
Simon Modelling CB&Q and Wabash See my slowly evolving layout on my picturetrail site http://www.picturetrail.com/simontrains and our videos at http://www.youtube.com/user/MrCrispybake?feature=mhum
Martin,
Curious, is the instructions for wiring the second control/booster included with the manual for the set/booster?
I'm the one who usualy says "if you want to expand, buy a Super Empire Builder". I also always qualify it with saying IF YOU NEED ANOTHER DT400. For exactly the reason mentioend above - the set combination is less than the individual prices of the DB150 and DT400. Plus you get a UP5 thrown in.
But if you do NOT need a second throttle, it's cheaper to just get the DB150.
I also recommend no one get the Empire Builder as their only set. The lack of CV readback and program track are the two biggest issues. IMO, not having a dedicated program track makes it HARDER for a beginner, not easier. There is the potential to accidently program every loco, and there is no safe low-current location to test a decoder installation ebfore puttign it under full power. You can avoid the first problem and simulate the second with a toggle switch and the resistor that comes with the LT1 tester - but now we're back to wiring up DPDT toggles and isolating track sections. Isn't it easier to just hook two wires to a piece of track and a couple of terminals labeled "Program"? Then, always test a new installation on the program track first. If it won't program or read back, something's wired wrong, but since the current in the program track is very low, it won't fry the decoder. Fix it and get it to work on the program track first and you'll know that at least it won't smoke when you put it on the main.
and if you get a short running from one power district to the next, change the rail out leads on the DB150.
You'll continue to use the DCS100 for the programming track. To make sure we're clear here, your DCS100 will power one part of your layout and the DB150 another. This means you'll have gaps setup and the layout dvided into at least two blocks, each powered by a different booster.
.
martin,
thanks for clearing that up. I rember now the you dont have a program track with the DB150
Purchasing a Super Empire Builder starer set will get you a DB150, Dt400, and a UP5 for less money than buying them separately.
The DB150 can then be used a a booster only by installing a jumper wire between the ConfigA terminal and the ground terminal. You also need a loconet cable between the DB150 and the Command station. Doesn't hurt to add a larger gauge ground wire connection between the two as well. 14awg would be fine.
There won't be two command signals because installing the jumper wire disables the command station in the DB150. As a "booster only", DB150 just boosts the signal sent by the one and only command station.
Why get a Chief to be the command station? You will gain all of the extra features that Chief has to offer:120 slots vs 22Separate current limited program outputCV readbackRoutes
hello,
I have a digitrax super chief, did i read correctly, on another post that i can buy an empier builder starter set and use the DB 150 as a streight booster, and also have a 2nd dt400 Wont this put 2 dcc signals on the track at the same time. If not why did i not just buy the empire builder and add another empire to expand insted of sepnding the extra money on a my chief.