Hi All. I am in the design phase of my new layout. I have an NCE PowerCab, but plan to upgrade to a SB5. I am thinking of going with the Cobalt IP Digital switch machines, mainly due to how incredibly easy there are to wire up. I was watching a video by Larry Puckett (Model Railroading on YouTube) and he did a couple of videos about how simple this switch machine works. In subsequent videos, he suggests having a separate accessory DCC power bus for the turnouts. Question, have any of you set up a separate accessory power buss for your switch machines? Did you power it with the same dcc system booster that powers your track? In my head I am thinking powering the Accessory buss just as if it was another block on the layout. Larry suggested to use a second booster, but if that was the case, how would the DCC signal get from the main booster to the accessory booster? This would be important because the Cobalt IP Digital has an output to power the frog.. Am I making sense? LOL
This might answer some of the questions and I would assume it would probably apply to other products also. https://www.tamvalleydepot.com/products/dccbooster.html Sumner
Basically, with DCC controlled turnouts there are three ways to power them: From your track bus. That's fine as long as you have enough power and since those don't draw much you most likely would. There only real problem with this method is if you have a short you can't operate the switch machines until the short is cleared. Where this is really an issue is when you run an improperly lined turn out - the easiest way to clear the short is to throw the turnout but you can't because of the short. That means you have to manually move the train to clear the short. Separate circuit breaker isolated busses but track and switches still running from the same booster. Again, you have to have enough power for the trains and the turnouts. You don't necessarily have to have a circuit breaker on the turnout bus, but you do have to have one on the track bus so that if you have a short on the layout you can still throw the turnouts. Separate booster for the turnouts and track buss. This is generally only needed on large layouts with lots of switches. There's certainly nothing wrong with doing it on smaller, less power-hungry layouts, it's just not necessary. The command station outputs a low power DCC signal that the booster boosts to output to the track. Most DCC systems have the command station and first booster in the same enclosure but functionally they are still separate components with the low power signal also accessible to the outside. If you add more boosters they use this same low power signal so that all of the boosters will have the same output. I took a look at the manual and personally I don't like the way they do the frog. Usually you have the frog on the same bus as the track but the way they have it, if you have a separate turnout bus the frog will be powered by the turnout bus instead of the track bus. It seems to me that you could have the turnout bus shutdown if you cause a short by running a turnout.
Thanks Sumner, I think this is exactly the solution I am looking for!! And its much cheaper than buying a second booster, AND is still simple to wire up! Also, with that booster I wont be robbing power from the track bus.
I did some more looking and the Cobalt IP does have a second internal switch with all three terminals brought out that you can use to power the frog. If using this with separate track and accessory busses you really should use the second switch for frog power and have it's inputs connected to the track bus. It's still buying a second booster, it's just much less expensive than a traditional "plug and play" booster from the typical DCC manufacturers. An added feature of that booster is an "accessory" mode which will supply DC power to the accessory bus in the event of the DCC signal being shut down. What that does is allow you to get the DCC signal for this booster from the main booster's output without having a separate circuit breaker for the track bus. If there is a short on the track bus, you can still throw turnouts as long as you have local pushbutton control (you wouldn't be able to throw them with DCC commands because the DCC signal would not be getting to the accessory decoders). If using the accessory mode of that booster, I absolutely would not use the frog output of the Cobalt IP because in the event of a track short you would have DC power on the frog of the turnout. An alternative would be to feed this booster the low power DCC signal from the command station. With that alternative, if there is a short on the track bus you can still throw turnouts using DCC commands. If you want to feed this booster with the main booster output and be able to throw turnouts with DCC commands during a track short, you still need a circuit breaker to isolate the track bus from the accessory booster input.
Question: I have Tam Valley boosters and circuit breakers that I will be using. I will wire from the Command Station to a couple boosters and then have a couple circuit breakers after the booster to help identify a short quicker. Command Station is DCC++EX. 1. No track or accessories will be powered by the Command Station. It will only provide the DCC signal to the boosters. I'm thinking that in my case if there is a short in any district powered and protected by either a booster (as they also act as a circuit breaker) or a circuit breaker after a booster that only that district will shut down and anything in any of the other districts will continue to work normally and still be able to be controlled via DCC. Is that correct? 2. Also in the scenario above as long as the short wasn't in the accessory district (after that dedicated booster) the accessories wouldn't need to be shut down after 5 minutes so one wouldn't have to use the accessory mode on the booster if they didn't want to. Is that correct? At the moment I don't plan on having any DCC accessories but who knows down the line. Thanks, Sumner
