In my couple of years in lurking and reading TrainBoard, it seems obvious that most of you are N-scale. DCC EX can handle multiple locos and consists with the typical current draw of N-gauge locomotives at 1/4 A. If your interest is HO, though, the current draw (~very average) goes up to 1/2 A, or more, per loco. At the DCC EX basic current limit of 1.5A, HO-ers can have that in a single consist, much less trying to run several trains at once. My interest is also passenger trains, so lighted cars exacerbate the current draw even more. (Yes, I understand it's much more involved to be accurate with current draw. For bulk estimates however, the 1/4A and 1/2A are good enough.) Don't get me wrong - I've built a DCC EX command station with the WiFi shield and use it regularly for my test track, along with JMRI Decoder Pro. I've had absolutely zero issues with it! I'd just as soon pursue DCC EX for my entire layout plans - it's that good. Now with servo control and EX-Rail, it's even better. Or, I should say - everything I've been looking for(!), with the exception of current handling. Methods that exist to overcome that current limitation (with power districts, of course), are fuzzy. There are different motor shields, but they all seem to need some sort of opto-controller to work with a DCC EX command station. OTS boosters might be an option, but connecting to DCC EX again gets very fuzzy with mentions of an opto-controller or a LocoNet interface board. Bottom line, the DCC EX current limitation appears to be a show-stopper for HO. Please correct me if I'm wrong. ;-) I have some questions: 1. Why are opto-controllers mentioned so much for boosters using DCC EX? I have no issue with building add-on PCBs, but opto-control for the DCC signal seems like a kludge, at best. Why not just read the buss from the DCC EX command station? Is it because DCC EX has no internal networking capability that can interface with an OTS booster? 2. Would use of an OTS booster, such as Digitrax, require the LocoNet interface PCB? 3. Since DCC EX can work on WiFi, is it the preferred networking protocol? If not, how do you ever connect a booster (or anything else) and interface with the DCC signal? 4. Is there some sort of architecture diagram in work for DCC EX - something that might show proposed peripherals and their connections? The DCC EX website's "The Big Picture" is a good start, but again - it seems to gloss over this current limitation. On GitHub there is an open item about using a DCC EX command station as a Smart Booster, but it doesn't seem like it's going anywhere at the moment. As an HO-er, I'm having trouble understanding how to move forward with DCC EX, outside of my test track and programming use, unless all one would want is to run one or two HO locos around a loop. P.S. I'm still very new here and none of this is intended as a slight toward DCC EX - far from it. The work is simply outstanding. People are saying that even the support is as good or better than OTS DCC mfrs. I'm just confused about the current limitation and looking for help.
The limitations that you mentioned are there in most 'starter' systems from about any of the DCC manufactures and you are going to spend more money to get around them regardless of the DCC system used. The solution for them and DCC++EX is 'booster's as you mentioned. DCC++EX can run with probably about any of them. I've decided to go with Tam Valley myself and can get a 3-5 amp booster for about $65 delivered. Check the other manufactures also. My layout is fairly large at 6' x 24 foot but I'm a single operator and a lot of that is scenery. Still I'm going to get multiple boosters and circuit breakers for the layout. I'm N scale but you'd do about the same with any layout that is larger or needs the amperage. My DCC++EX command station will only provide the DCC signal. If you want to build your own there are options out there like Dave's booster ( HERE ). I have the parts but decided not to build it as I want to put my time to something else. Maybe look into it or I think the DCC++EX guys are also exploring booster options. If you don't want multiple power districts (or even if you do) you can go to a motor board/shield that accepts more power than the basic motor board/shield. How about 43 amps? IBT_2 BTS7960 Motor Board One would give you all the amps you need for the main and if you wanted more for the program track you use two. You change the config.h file to set the new current limit. You could still have different power districts with lower amperage circuit breakers to each one. The disadvantage, as I see it, maybe wrong, over the boosters I'm running is that an overcurrent could shut the whole command station down (safely) where the boosters and circuit breakers I'm using only cut power to the one district. Maybe with circuit protection (a simple fuse??) and using the 'IBT' the command station wouldn't shut down. So in summary don't see any reason to not use DCC++EX with any size layout or scale if you want to. Sumner
I would recommend you post this question on the dccex discord channel they answer sometimes within minutes! I don`t know the technical part of what you are asking but I have a dccex command station built using the bt2 motor driver it is capable of suppling 43 amps. I have a 4.5 amp power supply so I have mine set to trip the overcurrent output at 4 amp maximum output but if you have a power supply rated at more amperage than mine you could go up quite a bit. My layout is 20 ft by 20 ft and have had 6 locomotives running at the same time on it.
Thank you for this response. Yes, I've seen Dave's booster and was actually referring to it without name, when I mentioned the Opto-Coupler. He states that it is needed to enable it for operation with a DCC EX command station. You mention that you're buying the Tam Valley booster, which is the economical choice for off-the-shelf. However, one of my questions regarded basic connectivity to a DCC EX command station. The Tam Valley page markets the booster for "accessories," but to use it for a power district tied to a command station, it then mentions LocoNet. There is some discussion that you can connect it to the rail power on a Digitrax command station, but then it states that it will be distance-limited if LocoNet is not used. That all goes back to Dave's booster and why he built an opto-coupler (along with a transistor converter circuit at the connection between command station and booster - whatever that does). This tells me it's not as simple as purchasing an off-the-shelf booster such as the Tam Valley one, connecting it to rail power from a DCC EX command station, and expecting it to work.
Thank you! This confirms for me that a higher-amperage output is possible with a different motor shield, but it doesn't really address the question about boosters. The DCC EX guys repeatedly state that if you think you need as much as 5 amps, you better be using power districts and splitting that current up. I'm trying my best to design a double-decker layout, with an additional lower level for staging. The room is about 11.5 x 21, so I was thinking about using at least one power district per level. I guess it could all be handled by a single command station at 5 amps and using a PCB with a bank of circuit breakers, but the more elegant solution is to use boosters. If one is planning ahead, the "future upgrade" pathway for boosters is clear with Digitrax, not so much with DCC EX. I greatly appreciate your advice and will try to work up to posting my questions on Discord.
With DCC++EX you have the option of the different motor shield but also can easily use boosters. You would use the boosters exactly like you would with Digitrax. They sell them so probably explain them in more detail. Here is an example using a Tam Valley booster for instance... The Command Station would be your DCC++EX command station. The outputs from it would go to however many Track Boosters you wanted to use and or also one or more Accessory Booster. From Tam Valley....You can also use the booster as a "powered circuit breaker". It fills all the functions of a circuit breaker but provides its own power. Each of your power districts puts no load on the command station as it is fully buffered. I use several of these with 16 V power supply which gives about 14.5 Volts on the track to power my own layout with just a single NCE PowerCab. The NCE PowerCab is similar to the basic DCC++EX command station with both capable of less than 2 amps of output (without the use of a booster or larger motor board/shield) but running with boosters capable of about anything you want to do. Instead of thinking upper or lower level think about power usage in your districts as to how many locos could maybe running at the same time in that district. Also how you can set the districts up to diagnose a short easier. Sumner
I think that graphic belies the complexity of what's going on. I downloaded the Tam Valley manual and studied the photo of the PCB. The arrow below is pointing to a white chip in a DIP-8 planform (TVD should've socketed it). It's a 6N137, an Optocoupler. So this is how the Tam Valley Depot booster can work with a wide range of DCC systems and why Dave made an optocoupler for his H-Bridge booster. However, this statement on Tam Valley's website still has me concerned: "To use the booster with Loconet you can connect it to the railsync lines (the outer pair in the loconet cable) or to the rail outputs of your commend station. The Loconet method has the advantage that the signal can be sent farther without significant degradation in quality." This implies that using the optocoupler method to sync the DCC signal has worse distance limitations than LocoNet alone. It would be helpful to know that specific distance limitation. For instance, I just watched one of Tom's Trains videos last night, where he assembled a bunch of peripherals around a DCC-EX station, using an I2S buss hub. I think that's the limitation of DCC-EX regarding peripherals (including boosters, remote servo controllers, etc.). Its only connectivity buss appears to be I2S, which from my experience in other electronics is about 10 feet. Maybe you can use wi-fi or ethernet protocols to tie together multiple DCC-EX units together, but that may require JMRI to make it all work. I don't know what NCE uses, but LocoNet could be one of those things that's hard to do without if your layout has any distance on it.
I don't have a strong enough electronics background to answer some of your questions but I did just run a test to alleviate any concerns I might have about using the boosters I bought. I went out and made an extension cable out of 20 or 22 gauge wire 28 feet long that I had. I connected one end to the 'Main Track' connector on the command station. Stretched the wire out in the shop and connected the other end to my test track and started up the DCC++EX command station. Pulled up EngineDriver on the phone and connected. Selected a loco and it ran fine. I didn't connect a booster and then connect it to the track but assume that the booster would of gotten the same signal the engine did. My layout is 6' x 24.5'. I'll have the command station about 1/3 of the way along it. I plan on Having the boosters very near to it and then will run 14 gauge buses off of them to the different power districts and drop feeders for ever track section (3 ft flex track) to the buses. I feel that this is going to work for me. I'd suggest putting your questions out there to the guys on Discord. Also since you have a DCC++EX Command Station proceed with it and if there is a problem then look at spending the money for something else when the problem does arise. Please keep us up on what the final solution is/was. I don't plan on using LocoNet so haven't studied up on it but recently did find this video. Not sure if it will answer any of your questions or not ... Sumner
Yep. The IOTT guy has been doing yeoman's work on model train control networking. I just wish he didn't stand and lecture in all his videos. I get the feeling I'm back in class watching one of his videos. ;-) Thank you for the test! I'll keep studying and try out Discord when I get a chance!
From Tam Valley's statement, I took it that transmitting the RailSync (low power DCC waveform, part of Loconet) signal over Loconet wiring preserves the signal integrity far better than sending DCC over the track wiring (and the track itself), given all the stubs and such accompanying the track bus, not to mention the locos drawing power from it. Thus, a booster driven from Railsync is immune from noise generated on the CS DCC track bus.
