# power supplies for mth dcs



## mark d (Mar 11, 2012)

How many power supplies can I hook up to the MTH DCS System? I have two 100 w mth power supplies now, and if I expand my layout, can I hook up another 100 w to it? Someone at my hobby shop told me I be better off buying the MTH Z4000 transformer to power my layout, but I'm not sure how I would hook it up to the dcs system. Has anyone used a MTH Z4000 with dcs? I'm not sure what I can do. mark d.


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## Big Ed (Jun 16, 2009)

mark d said:


> How many power supplies can I hook up to the MTH DCS System? I have two 100 w mth power supplies now, and if I expand my layout, can I hook up another 100 w to it? Someone at my hobby shop told me I be better off buying the MTH Z4000 transformer to power my layout, but I'm not sure how I would hook it up to the dcs system. Has anyone used a MTH Z4000 with dcs? I'm not sure what I can do. mark d.


BUMP for you.

This is a question for our in house MTH ASC Certified Tech. 
John?


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## gunrunnerjohn (Nov 10, 2010)

You can use any combination of power inputs up to 180 watts for each channel of the MTH TIU. The Z4000 would work fine, as will almost any other sine wave transformer. Don't use transformers with electronic controls that vary the voltage. At our club, we have four 180 watt bricks powering the TIU, one for each channel. Here, I have two 180 watt bricks and I parallel the inputs for one fixed and one variable for each brick.

You could add another 100 watt supply, but remember that you can NOT parallel the outputs, so anything running on the tracks connected to a single TIU output would be limited to 100 watts total. 

For any transformer that doesn't have a modern circuit breaker, you MUST provide a fast acting circuit breaker or fuse between the transformer and the inputs of the TIU.


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## mark d (Mar 11, 2012)

When you say not to parallel the outputs, does that have anything to do with the lockons that are on the track? I have one lockon on the outside track and one on the inside track parallel from one another.


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## gunrunnerjohn (Nov 10, 2010)

Well, you probably should have more than one lockon for a loop, but that's a different story. 

What I'm saying is, the outputs of the TIU channels must NOT be electrically connected to each other, they each feed a separate power district on the layout.

The inputs can be paralleled to provide power to more than one channel from one transformer.


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## mark d (Mar 11, 2012)

Would a Z-4000 be easier to hook up for DCS than having 3 to 4 power bricks? This way I know I have the power as I expand my railroad.


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## gunrunnerjohn (Nov 10, 2010)

Well, the Z4000 would work fine, as for easier, that's for you to decide. I know I want more than 100 watts for a single power district, as having a couple of passenger trains on a loop would exceed that. I personally like the 180 watt Lionel bricks for DCS. They have the best circuit breaker of any of the modern transformers, and they also give you the full 180 watts for a channel. No handles, no fuss, just power them up and go.


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## mark d (Mar 11, 2012)

So, if I go with two Lionel 180w power bricks, I connect them to the fix inputs of the DCS Imputs of the TIU?


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## gunrunnerjohn (Nov 10, 2010)

Yep, and you can parallel them to the variable inputs as well, that's what I do. Then I can just swap the outputs to the track from the fixed outputs to the variable outputs and run conventional stuff.


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## mark d (Mar 11, 2012)

Do you think two power bricks (180W) would be enough to power a 8 wide by 18 length ft running three trains?


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## gunrunnerjohn (Nov 10, 2010)

Plenty of power, we ran 4-5 on the modular layout with two 180W bricks. We have since gone to four bricks, but we have more modules and figured we might need more power.


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## mark d (Mar 11, 2012)

John, one other question. I'm using 18 guage wire for the DCS set up. Some one told me to use 16 guage from the power bricks to the TIU, and 18 guage for the rest.


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## gunrunnerjohn (Nov 10, 2010)

Actually, you should be using at least 16ga all around. The longer the run, the larger the wire should be. The run from the transformer to the TIU is typically very short, seems pointless to get worked up about the size of that one.


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## mark d (Mar 11, 2012)

Thanks, John. You'll be hearing from me again, soon. I'm learning, one thing at a time. mark d.


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## gunrunnerjohn (Nov 10, 2010)

Everyone starts at the same place, with a clean sheet of paper.


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## mark d (Mar 11, 2012)

John, I'm back again. I Have two of the MTH TIU/Barrel Jack Adapter Cables. It doesn't look like 16 guage wire. Can I use them to connect them to the Lionel 180W power bricks and to my DCS TIU?


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## gunrunnerjohn (Nov 10, 2010)

Well, you're going to be connecting the bricks to the banana jacks on the TIU, so the barrel jacks don't seem to be all that useful. I make adapter cables that go from the Molex connector on the PS180 to banana plugs and use those to connect my PH180 to the TIU.

You can use one of those MTH power supplies to power just the TIU, there is a benefit to having the TIU always powered in case channel 1 trips out. You won't lose the other channels in that case.


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## mark d (Mar 11, 2012)

So, the 180ps wire plugs right into the TIU Banana jacks?


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## gunrunnerjohn (Nov 10, 2010)

You need an adapter, the PH180 comes with this kind of connection.


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## mark d (Mar 11, 2012)

Does Lionel have these adapters already made for this?


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## gunrunnerjohn (Nov 10, 2010)

Here's one I made. Lionel has adapters that go to bare wire, not to banana plugs.


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## mark d (Mar 11, 2012)

John, could you give me the part no for those Lionel adapters with the bare wire?


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## gunrunnerjohn (Nov 10, 2010)

I suppose there is, but since I make my own, that kind of research has never been done.


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## mark d (Mar 11, 2012)

John, do you know the part no of those Lionel adapters with the bare wire? Is it part #6-12893, power adapter cable?


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## gunrunnerjohn (Nov 10, 2010)

I think these are the ones you need: Lionel 6-14194.

You can use the center two for the two PH180 plugs and just cut the others ends off and use the binding posts to secure them to the TPC. You could also put some banana plugs on them as I did for my jumpers.


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## mark d (Mar 11, 2012)

John, I'm going to use my mth 100w bricks for now until the lionel ones come in. The hobby shop near my house told me to plug both 100w bricks into fix imput 1 using the mth barrel jack adapters. Is that right?


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## gunrunnerjohn (Nov 10, 2010)

I would not parallel those 100W supplies, but that's just me. I know people that parallel transformers, but IMO that's not a good practice.


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## mark d (Mar 11, 2012)

I was told to use fix imput 1 only. I thought you plug each brick into fix imput 1 and fix imput 2.


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## gunrunnerjohn (Nov 10, 2010)

That's what I'd do.


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## mark d (Mar 11, 2012)

Do I use a terminal block for each outer loop and inner loop of track, and connect one to 1 fix terminal imput and 2 fix terminal imput?


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## mark d (Mar 11, 2012)

John, I called MTH today and talked to a service tech and got his imput, too. He told me it's okay to connect both 100w bricks into fix imput 1 using the mth barrel jack adapters.


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## gunrunnerjohn (Nov 10, 2010)

Well, it'll work, but I personally wouldn't do it.


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## mark d (Mar 11, 2012)

If I connect each power brick to each fix imput, do I need two terminal blocks?


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## gunrunnerjohn (Nov 10, 2010)

You don't need any terminal blocks if you don't want them. Where are you thinking about terminal blocks?


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## mark d (Mar 11, 2012)

My lockons on the track where my wire is connected to. Doesn't the wires from my lockons have to go to a terminal block, and from the terminal block wires go to the imput out on the TIU?


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## gunrunnerjohn (Nov 10, 2010)

You can go directly to the TIU, or you can use terminal blocks.


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## mark d (Mar 11, 2012)

I have four lockons on the outer track and four on the inner track. I was going to have a terminal block for each outer and inner track, and connect each block to fix 1 and fix 2 out puts.


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## gunrunnerjohn (Nov 10, 2010)

Did you read the part about using a star configuration for wiring for DCS? You might want to optimize the wiring for DCS if that's what you're going to run.


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## mark d (Mar 11, 2012)

I don't understand the star configuration, John. Is it easier to do. Can you go into detail about it?


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## gunrunnerjohn (Nov 10, 2010)

If you don't already have it, I suggest this book: DCS O Gauge Companion 
Digital Book.

Basically, star wiring is running a wire from a common connection point (like a terminal strip) directly to the power drop for each power drop. In addition, you will have insulated rails between power drops to avoid creating signal loops that corrupt the DCS signal. 

The other common wiring scheme is bus wiring, which is running the supply wire along the track and having multiple drops from the track to the supply wires. However, this is not optimized for DCS.


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## mark d (Mar 11, 2012)

John, I think I'm going with the mth Z-4000. Fix imput 1 to Z-4000 and output 1 to terminal block to my track. Will that work?


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## Lynn D Bennett (Jul 27, 2013)

mark d:

John is right if you can find the Lionel 180 watt Power Bricks. They appear sometimes on EBAY in the $100 price range. They are not available new even though they are cataloged and an email to Lionel recently stated there was no known schedule for their return to the supply chain. I wanted new and was forced to buy the readily available 100 watt MTH Power Bricks. Here's my experience with them.

I, at first, connected one to the Fixed DCS TIU channel input and another one as the power source for the Accessories Interface Unit (AIU) to run the switches and operating buildings on my layout. But every time I had a derailment and shorted the track the 7 Amp circuit breaker in the track Power Brick would not actuate fast enough and the 20 amp internal automotive fuse inside the TIU would blow. This happened at least half a dozen times before I made a change. By the way, the 20 amp fuses require disassembly of the TIU and the 20 amp current surge inside the TIU can not be good for its longevity.

I went to Passive Mode. That connects the Power Brick directly to the track and the track to the output of the TIU. The result is the current to run the trains does not go through the TIU (it bypasses it) but the control signals ride on the AC power of the Power Brick. This at least protects the TIU from excessive current flow. But the slow to operate circuit breaker on the track Power Brick was protecting nothing so I added a fast acting circuit break in series with the track. It is a 7.5 amp breaker that trips immediately and protect everything. If you search out my post on this site you will be able to find my source of this circuit breaker.

I run a MTH RailKing lighted passenger train and a MTH Premier freight train with no problems on my 9 x 7 foot layout. I use four lockons for power deliver to the track. There are no blocks or divisions. It is all one big electrical circuit. I am saved by the fact that any accessories and switches are run by the second Power Brick (also the MTH 100 watt unit). The switches do not use track power and are so wired. Only the common of both Power Bricks are interconnected.

All of this has worked out fine for me but as John said the best Power Brick is the 180 watt Lionel one, not the MTH 100 watt unit. The Lionel 180 watt Power Brick circuit breaker is said to be very much faster than the circuit breaker in the MTH 100 watt unit. Too bad Lionel is no longer keeping it in stock or doesn't even have a schedule for re-introduction of it into the supply chain. You can find them used on ebay, I'm told.

I really don't think you need the big Z400. The limit of power through the TIU about 180 watts per channel. If your layout is big enough you may want to use more than one TIU channel and break the track up into two section. For my layout I did not find that necessary but it really is small at 9 x 7 feet but uses over 100 sections of RealTrax. I run two trains simultaneously with one TIU channel and one remote. So ?????

I am not aware that each lock-on (power drop as John calls them) has to be on an isolated section of track. My understanding was you can have as many lock-ons on the loop as you might require. There are no isolated track section on my layout and my DCS signal survey done using the remote gives 100% all the way around both of my loops. I use the star wiring as well. I may be wrong but the proof of the pudding is in the eating and my layout works fine the way I did it (??).

Good luck with your layout. If in doubt listen to what John says and not me. He is the expert, not me. He also has lots of experience with larger layouts. I only offer what i have done that is successful for me.

LDBennett


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## gunrunnerjohn (Nov 10, 2010)

You don't absolutely need the isolation for power drops for smaller layouts, as the signal degradation isn't sufficient to cause an issue. However, as the layout gets bigger, the wiring practices become more important. There have been volumes written about DCS in larger layouts and the wiring practices that work and don't work. Many of these lessons were learned at places like the NJ Hi-Railers and similar clubs that have extensive DCS and Legacy installations.


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## mark d (Mar 11, 2012)

I think I'm more confuse now. The DCS manual talks about using a terminal block to connect your wires from the lockons. There's nothing about bypassing the TIU imput with your power source. It says to plug your power source to the TIU imput and your terminal block to your TIU output. If I have 8 lockons, how can I not have a termina block, and connect those wires directly to the TIU output? Am I missing something?


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## gunrunnerjohn (Nov 10, 2010)

You can use a terminal block, that's not a problem. If you're running the star wiring, that's the easy way to do it. Some folks just splice them together and run them out to the drops.


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## mark d (Mar 11, 2012)

Thanks, John and Lynn. I'm beginning to understand now. Thanks for being patient with me. I have a lot to learn about this hobby. Talk to you soon. mark d.


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## mark d (Mar 11, 2012)

One final thought. I talked to Lionel and was told the 180w power supply will be coming out soon. They don't have a date set yet. mark d.


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## gunrunnerjohn (Nov 10, 2010)

The 180W brick is part of their GW-180 transformer package, so I know it'll continue to be produced. I got all of mine on the used market, but it'll be along at some point.

Lots of them on eBay, I'd use something like Gixen and put conditional bids on a few, when you get one, the other bids get cancelled. Very handy, I use it a lot. 

Try an eBay search for PowerHouse in O-scale trains


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## Lynn D Bennett (Jul 27, 2013)

mark d:

You are right about the "Passive Mode" I suggested not being in the DCS manual but it is clearly in the DSC companion manual suggested by John. It was a way I got around blowing fuses in the TIU. It allows much more power to be delivered to the track in DCS mode than the 10 amp limit of the TIU since no current goes through the TIU. The TIU just adds the control signals to the power supply output. It also avoids having to use multiple channels of the TIU to distribute the current load it sees per channel. For my smaller layout is was perfect for me.

That companion book covers the wiring in much more detail than the DCS Manual.

LDBennett


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## gunrunnerjohn (Nov 10, 2010)

We run our club layout in passive mode. It just worked out that it was easier that way. Also, since it's my TIU that we're using there, I figure there was less risk to it.


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## Lynn D Bennett (Jul 27, 2013)

mark d:

As for paralleling Power bricks, that is not a good idea. If due to manufacturing tolerances one power brick puts out a voltage different than the other there will be leveling when connected together and currents from one flowing in the other, wasting some of the power as heat inside the power bricks.

I think your idea of connecting one power brick to TIU fixed #1 and the other to TIU fixed #2 and splitting up the layout into two loops is an excellent idea. Mount two terminal block close to the TIU, one for each fixed channel of the TIU. Then from each Lock-on run the pair of wires to the terminal block. Next wire the terminal blocks individually to each TIU channel. That is Star wiring. The long runs go too the terminal boards and the terminal boards are connected to the TIU with short runs. The advantage is you get the most copper conducting the current and the least drop in voltage to the track due to the wires resistance.

But be aware that the circuit breakers in the MTH 100 watt power brick is not fast enough and you will be blowing TIU fuses if any of the track gets shorted (actually a common event). You would then have to unconnected the TIU and disassembly it to change the fuse. It is a 20 amp fuse and that amount of current going through the TIU can harm it. Passive Mode eliminates that possibility but a fast acting circuit breaker does the same. Most circuit breakers you can buy from Electronic Stores are not nearly fast enough for our uses. The one I used was:

AirPax T21 with a -61 trip speed

Where I got mine (and the link to the specific part doesn't work anymore) was Data Com Solutions. A work around is to wire the TIU in the Passive Mode. Without doing that or without the fast acting circuit breaker or a fast blow external fuse you are risking the TIU. John was so worried about his loaned out TIU for his Club layout getting smoked that he wired it in the Passive Mode. If you can get the Lionel 180 Watt Power Brick its circuit breaker is fast enough.

Do get the DCS Companion Book. It covers the wiring much better than the DCS manual.

These are just my thoughts and are based on my engineering background. John is certified by MTH and is an engineer as well. We don't conflict in our recommendation here but there is more than one way to "skin a cat". My DCS experience is limited to my smaller layout and John's experience is for larger layouts, club level.

LDBennett


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## mark d (Mar 11, 2012)

Lynn or John, I have a question about passive mode. If you wire the power brick to the track, do you do it to the terminal block that is connected to the lockons? And the TIU output, how and where do you connect that to?


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## Lynn D Bennett (Jul 27, 2013)

You wire the power brick to the terminal block that distributes the power to the track. The TIU is also connected by its output connectors to the terminal block. There is no power to the input of the TIU. It is powered up back through its output terminals.

The red emergency button on the remote will no longer work. I use a remote lamp controller I got at Home Depot to control the power brick as an emergency off remote control. It has a key fob controller.

Since no power goes through the TIU, which has a limit of about 10 amps, very much more powerful AC power sources can be used. But some circuit breaker protection should be provided. A fast acting circuit breaker like I suggested in the earlier post is necessary to keep from having welding taking place where the track inadvertently get shorted by a derailment.

Below is a copy from the O Gauge Campanion for Passive Mode (Sorry, it got attached upside down but printing it out will solve that):


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## gunrunnerjohn (Nov 10, 2010)

Note that you must have either #1 fixed powered or use the aux power supply for the TIU. I recommend the aux power supply, that way if the track connected to channel 1 trips it's breaker, you don't lose control of the DCS stuff on other tracks.


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## gumguy (Feb 11, 2014)

Very informative discussion for my information. I have taken a leap of faith apparently in my 81 foot loop of track with one TIU, one mth z1000 brick attached to fixed #1, and z750 used as the TIU power source. My questions started as I have added 2 Mth steam locomoties both 3.0, 2 Mth Diesel 3.0, 3 Mth Diesel 2.0 with 2 lashed and started running them on all from the DCS remote. Until I added the steam locos I never noticed any difficulties then I ran them all still no problems until I turned the smoke on all and the transformer fuse stopped everything. Needless to say I only run one smoke unit at a time now. The setup also has six passenger cars and 4 other lighted cars. I am now aware I need some education advice on powering my Track. If I am listening correctly I need the Lionel 180 at least or go passive which I loose the emergency stop button which I have become accustomed to when I make a train management mistake going from one train to the other during the running of all 7 on one loop. My loop is around the ceiling of my 12 by 27 foot all purpose room. All suggestion appreciated on what I am doing. Thanks.


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## Lynn D Bennett (Jul 27, 2013)

First use the "STAR" wiring scheme (terminal block at transformer with multiple pairs of 16 gauge wires running to the track with lock-ons every12 to 24 feet).

Run Passive with a bigger 18 to 22 VAC pure sine wave transformer. To regain a panic button buy a remote lamp controller for less than $20 at home depot and plug the transformer into it.

People with larger layouts block the track in order to use multiple TIU's and power sources. I am not aware of exactly how that works but you are suppose to be able to move trains from TIU to TIU seamlessly from a single controller. Perhaps Gunrunnerjohn will explain it. His club layout uses this method, as I understand it.

Passive and many lock-ons with STAR wiring of 16 gauge may get you what you want. It is good to separate the accessories and switch controllers from the track power supply to assure enough power for the track.

LDBennett


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## gumguy (Feb 11, 2014)

Thanks for your reply. I do have one smaller loop on fixed channel 2 with switches and accessories but run only one locomotive with no problems. I am using 16 guage wire but no star or buss wire configuration on both. I have one lockon on the smaller loop, only 4 by 7. On the other main loop I direct connect to the center rail and outer rail of the 81 feet of fastrack. You suggest the Mth brick is not large enough. Is there no way to to run through TIU unless you have two TIUs splitting the track loop into 2 sections. I know you can treat the TIUs as one but one 10 amp transformer seems easier, but whose transformer and will that work without going passive? Thanks


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## Lynn D Bennett (Jul 27, 2013)

gum guy:

The limit is not the transformer as such but the current capacity of the TIU circuits. It is about 10 to 12 amps, I am told. When you go Passive you do not send any of the track current through the TIU. You just power up the track. The TIU is also attached to the track and it provides the command signals on top of the track voltage. All you loose in Passive is the emergency stop which you regain with the household remote lamp switch powering the transformer. I am wired this way exactly.

You really need Lock-ons for every 12 to 24 feet of track. It not only assures no dead spots but it also assures max voltage to all trains on the track and max DCS command signal strength everywhere.

I did not invent any of this. It is well documented in the "DCS Companion" book.

As for transformers avoid the high capacity in a small box variety as they may not produce pure sine wave AC, but rather noisy AC that interferes with the DCS signal that gets impressed on the AC track power. It is possible to duplicate the transformer function using switching processes that are too noisy for DCS. In the instruction manual for the DCS TIU there is a list of possible transformers know to generate clean AC.

Doing it the "DSC Companion" way assures trouble free operation of your layout. I think you should reconsider the way you have implemented your wiring and power sources. I can not tell from your posts but also get the switch motors off of track power and onto you accessories power source, if you have not already, to maximize the available track power. If your transformers are not 180 watt sources (10 amps at 18 VAC) you should consider the Lionel Power Brick 180 watt device. I use the MTH 100 watt power brick source and easily runs four engines (No smoke as it fills my house quickly). Modern MTH engines are pretty low power users compared to Lionel trains of old.

LDBennett


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## gumguy (Feb 11, 2014)

Lynn thanks for the help. I believe I understand more fully my requirements. First I need to add more lock-ons at the intervals you suggested, second add a Lionel 180 watt brick to channel one, third go passive if I am going to run that many locomotives( I did take 2 diesels off last night) and fourth purchase a remote lamp switch for an emergency remote. I am using another MTH 100 watt brick for my accessories and switches and I am not running them through the TIU. I do like the idea of having all channels covered by a Lionel 180 watt brick for switching between conventional and DCS but I have only been doing this since spring of this year so I need to walk before running and have a lot to learn. I eventually would like to add some Lionel TMCC and Legacy engines. 

Thanks again.


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## gumguy (Feb 11, 2014)

I forgot one I need to add the DCS companion to my list. Thanks


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## Lynn D Bennett (Jul 27, 2013)

Switches and accessories are directly controlled by the AIU product. It is basically a relay bank. The TIU controls the AIU which controls the accessories and the switches. No power for the switches and accessories goes through the TIU but only control signals. The AIU handles the power for the switches and accessories with the relays. Half of its output is dedicated for momentary power for the switches and half of the outputs are dedicated for continuous ON or OFF for accessories.

Read the DCS Companion book before you do anything. It is very enlightening. It can be tough to understand if you have no experience with DCS but that is not your case. You appear to understand the basics and the DCS Companion book will help you to decide how to do it all better. I am certainly not an expert on DCS. I have done my layout the way the DCS Companion suggests and have had zero problems. I have both the TIU and AIU with the MTH 100 watt power brick for the track and another MTH 100 watt power brick for the switches and accessories. I have four lock-ons for about 100 sections of track. The signal strength for the command signals is very close to 10 all around the layout when 5 is considered good. (The DCS has a mode where the engine sends back the signal quality live as the engine moves.)


LDBennett


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## gumguy (Feb 11, 2014)

Last night I added some star wiring to my layout and now have 10 signal strength all the way around the track. I do have one locomotive reading 23 and 24 volts while the other four are reading 16 to 17.9 track volts, nothing over 18 in the exact location. Any idea what is up with that? Thanks.


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## gunrunnerjohn (Nov 10, 2010)

If the one locomotive is a PS/3 model, it's a known bug with the PS/3 code and/or measurement hardware. I haven't heard of any move to fix it.


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## gumguy (Feb 11, 2014)

Yes it is a PS/3. Thanks for the information. I assume this will not effect locomotive operation. I have not noticed any glitches just the strange track voltage reading.


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## Lynn D Bennett (Jul 27, 2013)

The track voltage as measured by the engine (incorrectly in this instance) is not meaningful in DCS as the voltage is supplied continuously and at the same level to the track everywhere. But to get that condition you must use STAR wiring to lock-ons every 12 to 24 feet, in my experience. Getting a signal strength of 10 all around the layout is excellent results and shows that the STAR wiring probably makes a difference since the wiring and the track carry the DCS command signals.

LDBennett


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## gunrunnerjohn (Nov 10, 2010)

In answer to the original question, the erroneous track voltage reading is not significant as Lynn says.


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