Free-moN accessory bus question

[CNR5529]

Quick question for you Free-moN guys out there: from experience, what do you recommend to power the accessory bus? Is the cost of a dedicated DCC booster justified, or have you found that a simple 16V AC transformer is generally good enough?

[RBrodzinsky]

Silicon Valley FreeMoN typically runs the DCC signal on the accessory bus, with its own PSX.  But that is mostly because it is convenient, and we don’t have to bring something else to plug in. It then is up to the module builder to ensure they have the proper rectifier and voltage regulator for their accessories.

[jpwisc]

I use my accessory bus to power my tortoises and grade crossing flashers. I have a single 12V wall wart that I hook up to that bus.

[ryan_wilkerson]

I use NCE Switch-It connected to Tortoise machines and run them off the accessory bus. I remember a show with Rick and the rest of the SVL team where we were going to just give it non-DCC power but my Switch-Its needed the DCC signal to function.

[CNR5529]

Thanks for the insight guys.

@RBrodzinsky, when you say that SVFMN runs the DCC signal on the accessory bus with its own PSX, is this power coming from the same booster/command station that is feeding track power? Or do you guys have a dedicated booster for accessories? Running a separate protected circuit off the main booster would certainly be an easy solution to implement.

[RBrodzinsky]

Thanks for the insight guys.

@RBrodzinsky, when you say that SVFMN runs the DCC signal on the accessory bus with its own PSX, is this power coming from the same booster/command station that is feeding track power? Or do you guys have a dedicated booster for accessories? Running a separate protected circuit off the main booster would certainly be an easy solution to implement.

Mostly, just a separate protected circuit off the main.  On some occasions we've run a dedicated booster, mostly when dealing with other issues (like when, as it turned out, the main booster was starting to die - then the spare became the prime).

Just a reminder, the specifications say the Aux bus can be DCC, DC or AC.  Nothing utilizing it should rely on it being one of them (particularly DCC) when in a multi-group setup.

[CNR5529]

Just a reminder, the specifications say the Aux bus can be DCC, DC or AC.  Nothing utilizing it should rely on it being one of them (particularly DCC) when in a multi-group setup.

Good point, thanks! Our group is very much new to the Free-moN game, and as such we have the luxury of being able to specify/clarify whatever we think is best going forward, whether it is good practice, observations made by other clubs, etc. That's why I am curious as to what you guys have found in your respective groups. It sounds like there would be value in specifying either that all accessories should be able to handle any source of power (which the spec already hints at), or updating the standard to specify one particular power source.

That said, how would you handle getting commands to turnout/function decoders, like @ryan_wilkerson mentioned, if you only have an ac power source? Speaking of which, in a multi club event, how do you prevent your turnout decoder from accidentally being triggered when a switch on another module from another club is being toggled? I guess isolating the accessory bus into power districts and commands is also needed in this case?

[RBrodzinsky]

If you have an accessory which is a DCC decoder, then you should, at least, have a method to switch its input to the main bus, if not have it directly on it.  I also have some SwitchIts, utilizing the push buttons (same as Ryan). They only take DCC as power in, so I have them setup with PosiTaps to quickly change the power inputs, as necessary.

If the aux decoders have DCC addresses by which you want to activate them, then it becomes really messy when combining groups. Hence the detailed planning which goes into force usually about a year ahead of time (for major shows like NTS). Coordinating addresses, either static decoders for turnouts and (even more so) mobile decoders for everbody’s locos, is a major task. It is amazing how many folks have 844 or 4449 in their roster, for example. Typically, each individual is given a range of addresses available to them, and they need to reprogram their equipment to comply with the joint setup.

[CNR5529]

That all makes perfect sense. Thanks for the input!