RailPro > RailPro Specific Help & Discussion
RailPro and DCC discussion on Model Train Forum
Homeless by Choice:
The topic of RailPro and DCC systems was revisited yesterday, Feb 17, 2017, on the Model Train Forum (see link below and goto page one). Some of you may find it interesting and may care to comment. This particular thread was started back on Jul 25, 2016 and that was when I became aware of RP. Then I found this Forum and the rest is history.
If you are not allowed to post a reply/comment on the forum, you could email me what you would like posted and I can copy it as a reply stating your name or whatever direction you specify.
http://www.modeltrainforum.com/showthread.php?t=93649
One confusing point that is of no consequence to me is that one person called RailPro a 14v DC track system and another called it a 14v AC system. Which is it?
LeRoy
William Brillinger:
RailPro will run on 12 to 18V DC or AC, but the RailPro power supplies are 14V DC.
Homeless by Choice:
--- Quote from: William Brillinger on February 18, 2017, 10:35:42 AM ---RailPro will run on 12 to 18V DC or AC, but the RailPro power supplies are 14V DC.
--- End quote ---
Bill,
I have been thinking about this ever since I made the initial post and came to the conclusion that RP had to be DC because a reverse loop device is needed for loops. I answered my own question, came back here to post that conclusion and found your reply. It would be really nice if the track voltage was AC so reverse loop devices weren't necessary. I have a very limited understanding of electronics and have no idea how an AC radio powered control system could be designed thereby eliminating the reverse loop requirement.
Thank you,
LeRoy
William Brillinger:
--- Quote ---I have a very limited understanding of electronics and have no idea how an AC radio powered control system could be designed thereby eliminating the reverse loop requirement.
--- End quote ---
Alan?, I'll let you explain...
melarson:
--- Quote from: William Brillinger on February 18, 2017, 10:35:42 AM ---RailPro will run on 12 to 18V DC or AC, but the RailPro power supplies are 14V DC.
--- End quote ---
I have been searching all morning on this because I have a recollection that Ring specifically states not to use AC, but I can not find it. It might have been in an email or phone call with Tim. Either way, I can think of two reasons using AC would be unadvised and detrimental.
AC sine wave voltage levels are stated in terms of Root-Mean-Square (RMS), which is the equivalent ability of the same level of DC voltage (12VAC and 12vdc can perform the same amount of work). But the peak voltage of an AC sine wave (the instantaneous max and min of the sine wave) is the RMS value times the square root of 2. For a transformer whose secondary output is 12.6VAC, the peak voltage would be 12.6 x 1.414, or 17.8 volts. When rectified and well filtered, this is the raw, unregulated DC voltage that results. As you can see, 17.8vdc is very close to the upper end of what is recommended to power an LM. Saying that you can apply 12 to 18 volts DC or AC would lead the unsuspecting to think that 18VAC would be OK. It really isn't. Applying 18VAC to an LM would result in an internal DC level of 25.4vdc (sort of), well above the recommendation. Now, I say "sort of" because this would be the level of a well filtered signal. However, it takes fairly large capacitors to filter 60Hz AC to a nice smooth DC level; too big to fit into an LM. So the second problem is the LM would have an inordinately large amount of ripple on it's internal DC supply. Not desirable.
And then there is the question of whether the AR-1 would even work on AC. My educated guess is it wouldn't, but Tim would be the better person to ask that. I don't have a schematic to look at to determine the answer definitively.
--- Quote from: Homeless by Choice on February 18, 2017, 11:44:08 AM ---It would be really nice if the track voltage was AC so reverse loop devices weren't necessary.
--- End quote ---
In a 2-rail situation, using AC or DC wouldn't matter. There would still be a polarity (DC), or phase (AC), mismatch at the gaps, leading to dead short circuits when the gaps are bridged by your engine's wheels. In both cases you would need to account for this. The only way AC wouldn't also need a reverser is in a 3-rail system like Lionel or Marklin, where there is a center rail for one feed and the two outside rails for the other feed, and no matter how you set up your track, they never meet. BTW, this would work for DC as well, but who wants to run center rail? ;)
Michael
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