Digitrax hook up question.

[Howardr]

Hello all,

I've been using Bachman EasyTrack and I'de like to know the best way to hook up a Digitrax system to the track system.  Would the standard EasyTrack connections do?

Thanks.

 

 

[selector]

If you have the crossing piece that doubles as a rerailer, and it also has two elecrical tabs on the side, I don't see why you couldn't use those two tabs as direct connections...at least, for a total of about 12'.  Once you get beyond 10-12', your voltage losses will begin to impose themselves noticeably in engine performance deterioration.  So, you may, depending on your total trackage, have to use a short bus of heavier wire than the leads that normally attach to those two tines we were just talking about, and then solder feeders off that bus every 6' or so.

Note that you don't need the rerailer/crossing piece.  If you can solder, or don't mind learning the basics over the span of 20 minutes, just solder feeder wires of about 20-22 gauge to the sides of the rails...what we call the web.

[jamnest]

In between basements (home) I lived in an apartment.  I set up a large oval of EasyTrack on the living room carpet as a test track.  I used my time in the apartment to convert my locomotive fleet to DCC.  I have Digitrax Chief.  I ran an 18ga bus wire around the inside of the oval and connected the buss wire to the easy track connector/rerailer tracks.  I had severeal of them.  I turned on the command station and pluged them in one at a time as you will have a short if you get them reversed.  Your Digitrax command station will tell you if you have a short by beeping and shutting down.

This was my layout for two years, then I constructed a modular layout which could be moved from appartment to apartment until I could find a new basement for the layout.

[Howardr]

Thanks all for you replies.

[jeffrey-wimberly]

As can be clearly seen in this photo I use such connections where it's convenient. This one serves just 1 of 16 blocks.

[Last Chance]

I spread my feeders out around my Kato Loop because there is a marked loss in engine performance at the furthest point from the track feeder to the Chief. (I think 14 feet or so from the command station's feeder if that set is the only one active.) I plan a power distribution board in several locations to consolidate feeders so that the engine is no more than 3 feet from a feeder.

I have 14 gauge wire for power bus I can lay a pair all the way to the other end of the house and run the loop there if I have to. I deliberately oversize the wires and use big power to make it happen regardless of the metal rail on the layout. Some rails eat voltage more than others.

The feeders must not be more than a few inches because the potential load from the power bus will cause the smaller feeder wire to get warm if you try to make too long of a feeder. So the power bus wires can follow your track anywhere and it will be well.

Im assuming that you have the layout safely off the floor on a dedicated benchwork or table set. Running wires on the floor itself is a recipe for trouble.

[my05hammer]

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OK, I am posting only because this topic has me wondering.  It baffles me like the “Monster Cable” threads over at my favorite Home Theater forum. 

I am trying to be open minded about this so bear with me. 

Why do we need a “buss” when using DCC?  Why is the engine performance degraded after “X” amount of feet away from the power feed? 

I am having a hard time understanding this.  I am an industrial electrician for a local paper mill and while I am not saying that the buss is not necessary, I am just wondering WHY its necessary. 

The code 100 rail is about the equivalent of a 14ga solid wire.  According to my SquareD slide rule a 14ga solid wire is good for 15A of continuous power draw.  15 Amps, that’s a lot of locomotives in HO scale.  Is it the properties of the nickel silver that limits its capabilities? Is nickel silver naturally resistive?

At work we use nothing but Siemens PLC’s.  Siemens has a system of controls that work similar to DCC.  The “A.S. Network” has a cable (approx. 14 ga.) that stretches around a given machine, on the cable are sensors or actuators that clamp to and pierce the cable for connectivity.  These devices then are given an address and works similar to your DCC loco at home.  While there is a limit to how far we can run one of these network cables, and how many devices can be installed on the cable, it is by far more than the 12 feet or so suggested for DCC.  The cable is copper, so maybe there lies the difference?

Please enlighten me on why locomotive operation degrades after "X" amount of feet from the source without a buss.  I am starting the construction of my layout here in a month or two and do plan on running a buss because everyone states that it is required for good operation, and its going to be easy to install.  But I want to know why I am intalling it.  "Because they said so" isn't good enough.  I guess I want to know and understand the technicals behind why we run a buss. 

 

 

[jeffrey-wimberly]

Why do we need a “buss” when using DCC?  Why is the engine performance degraded after “X” amount of feet away from the power feed? 

I am having a hard time understanding this.  I am an industrial electrician for a local paper mill and while I am not saying that the buss is not necessary, I am just wondering WHY its necessary.

Many modelers use nickel silver rail. While it doesn't need cleaning as often as steel rail does, it's not as good a conductor of electricity, therefore there's more resistance, meaning the further the track goes the more the power drops. This can be a problem even on a simple 4x8 loop. The solution? Run a simple pair of 14 gauge copper wires beneath the layout from which smaller feeder wires can go up through the layout base to the rails. This keeps the amount of power on all parts of the track constant no matter how far the train is for the front of the layout.

[my05hammer]

Why do we need a “buss” when using DCC?  Why is the engine performance degraded after “X” amount of feet away from the power feed? 

I am having a hard time understanding this.  I am an industrial electrician for a local paper mill and while I am not saying that the buss is not necessary, I am just wondering WHY its necessary.

Many modelers use nickel silver rail. While it doesn't need cleaning as often as steel rail does, it's not as good a conductor of electricity, therefore there's more resistance, meaning the further the track goes the more the power drops. This can be a problem even on a simple 4x8 loop. The solution? Run a simple pair of 14 gauge copper wires beneath the layout from which smaller feeder wires can go up through the layout base to the rails. This keeps the amount of power on all parts of the track constant no matter how far the train is for the front of the layout.

Gotcha.  

Makes sense now.  I did not realize that the NS rail was resistive.  

Thanks. 

 

[WSOR 3801]

Rail is a poor conductor.  I think the actual material in cross section of code 100 rail is quite a bit less than 14 gauge wire.  Add in all the joints, switches, etc, and sometimes it is a wonder that anything moves.  I try to add feeders to every length of flextrack used, and connected directly to the buss (not 5-6 feet across the module, improperly terminated under a screw).  Might be overkill, but it isn't hard to do.  Things do seem to run better.  I spent a lot of time under the club layout fixing sins, and adding feeders in spots. 

On my 4x8 home layout, I soldered all the joints, except at switches.  I used quite a bit of Snap-Track, for the 18" curves I am stuck with.  Concrete columns do not move easily.

About 30 feet is the limit for buss length.  After that, another booster is recommended.  On the club layout (18 x 44 feet, C-shaped), the power comes in from one area, and the buss wires run around, about 50-70 feet (haven't really measured it).  We have circuit breakers hooked up, one for each of the blocks, as the layout used to be DC.  The yard is on the side farthest away from the power source.  We put another booster to run the yard.  You can tell when you get into the yard powered area, it takes off. The length of the wire run, and the plugs every 5-7 feet degrade the signal quite a bit. 

DCC was based on those PLC jobs you use at work. 

 

[wjstix]

For Bachmann EZ Track, you can also use the Atlas code 100 rail joiners with the connection wires soldered on.

[jeffrey-wimberly]

For Bachmann EZ Track, you can also use the Atlas code 100 rail joiners with the connection wires soldered on.

Just be careful with them. The wires tear off easily.

[Last Chance]

Ethernet requires workstations to be no more than 100 feet or so from the NIC to something else in the network. Binary signals are attunated or degraded over a long distance.

it is possible that with the roar of the house electrical systems which are not usually that "Clean" and the fade experienced by the binary signal as it flows to and from the engine decoder it's a wonder of technology how that Chip onboard manages to hear anything useful at all.

Also a Power bus with feeders every few feet bypasses the joints and flaws in the track and keeps the engine thinking it's no more than a few feet from the command station hearing the binary loud and clear. Savvy?

[NeO6874]

Ethernet requires workstations to be no more than 100 feet or so from the NIC to something else in the network. Binary signals are attunated or degraded over a long distance.

 

That's 100 *Meters*, or about 390"/300'/100 yd (all imperial values approximated) for 10/100/1000BaseT Ethernet (Cat5e/6 UTP cable).  ANY signal will attenuate over distance - same reason "standard" DC setupd need a wire jungle underneath for power (negating multiple-cab operation... that's a whole 'nother story)

it is possible that with the roar of the house electrical systems which are not usually that "Clean" and the fade experienced by the binary signal as it flows to and from the engine decoder it's a wonder of technology how that Chip onboard manages to hear anything useful at all.

 

I would expect that the rectifiers (and whatever fun electronics go into the booster/command station) would have some way of cleaning out the noise before sending out the signal... now you've gotten me wondering what the SNR is for a DCC system....

[Last Chance]

Well a SNR will be similar because DCC Loconet is the same as Ethernet using metal wires to transport the commands yah?

But if someone had to hit the limits of SNR, it's going to be a Mega Club that would have hit it way before a simple homeowner like me with a tiny room and 40 feet of wire. Ive just about exhausted my knowledge and just enough to hurt myself LOL.

[NeO6874]

Last Chance -- I think you're confusing Loconet with the DCC signal bus...

 

per my understanding, Loconet is only used for human interface/command interface between the throttle in your hand and the command station/boosters (additionally, every booster is linked to every other booster and the command station as well). IIRC this is a LV application, on the order of 1.5 or 3vDC.  In other words - loconet, while a "command" bus of sorts, is just the transport medium between you and the booster, and has no effect on the DCC signal itself.

However, you then have the ~12vDC(C?) that is wired to the tracks... it was this that I was referring to with the SNR comment.

[Last Chance]

I appreciate your thoughts on the matter.

[fwright]

Why do we need a “buss” when using DCC?  Why is the engine performance degraded after “X” amount of feet away from the power feed? 

I am having a hard time understanding this.  I am an industrial electrician for a local paper mill and while I am not saying that the buss is not necessary, I am just wondering WHY its necessary. 

The code 100 rail is about the equivalent of a 14ga solid wire.  According to my SquareD slide rule a 14ga solid wire is good for 15A of continuous power draw.  15 Amps, that’s a lot of locomotives in HO scale.  Is it the properties of the nickel silver that limits its capabilities? Is nickel silver naturally resistive?

At work we use nothing but Siemens PLC’s.  Siemens has a system of controls that work similar to DCC.  The “A.S. Network” has a cable (approx. 14 ga.) that stretches around a given machine, on the cable are sensors or actuators that clamp to and pierce the cable for connectivity.  These devices then are given an address and works similar to your DCC loco at home.  While there is a limit to how far we can run one of these network cables, and how many devices can be installed on the cable, it is by far more than the 12 feet or so suggested for DCC.  The cable is copper, so maybe there lies the difference?

Please enlighten me on why locomotive operation degrades after "X" amount of feet from the source without a buss.  I am starting the construction of my layout here in a month or two and do plan on running a buss because everyone states that it is required for good operation, and its going to be easy to install.  But I want to know why I am intalling it.  "Because they said so" isn't good enough.  I guess I want to know and understand the technicals behind why we run a buss. 

There are 2 buss involved with DCC.  The 1st is the power buss that links the track with the booster.  Normal advice is to use 12-14 gauge wire from booster to buss and for buss running close to track.  Short feeders (20-22 gauge typical) are dropped at regular intervals to tie the rail to the buss.

Reasons for power buss:

• nickel silver resistance is 19 times higher than copper.  Even though cross sectional area of rail is pretty decent, the higher resistivity hurts.  It hurts even more when using more scale size rail such as code 70 or code 55.
• rail joiners eventually fail as electrical connectors between rail sections.  Minute working of the joint by passage of trains, humidity adjustments of the wood benchwork, and oxidation of the rail joiner cause the almost knife-edges of the joiner to electrically fail in push-fit connection to the rail.  Failure to hold rails in mechanical alignment over long periods of time for the same reasons is another property of rail joiners.  Rail joiners are frequently soldered to help them maintain both the electrical and mechanical connection oover time.
• DCC is not very tolerant of voltage drops between command station and decoder.  Voltage drops are indicative of signal degradation, and can result in loss of comms or loss of response between throttle and decoder.  Published figures I have seen recommend maximum voltage drops of less than 5% (0.7 volts) for a DCC power circuit.  Remember, the DCC power buss (depending on booster and power supply rating) is called upon to carry 5 amps with that less than 5% voltage drop.

Yes, wire sizes on model railroads buss are frequently overkill.  But for many mr's the cheapest and most available wire of 16 gauge or larger is household Romex wire - 12 or 14 gauge.

The command or throttle bus is a much higher speed low current digital signaling circuit which links the DCC components.  Cat3 or 5 cable works just fine for this application.

hope this helps

Fred W