# Another DCC reversing loop question...



## pfdx (Jan 2, 2008)

I am considering converting my basement layout to DCC once the snow flies this winter. It is a loop to loop that uses EPL components and two relays to throw the loop switches and reverse polarity of the three districts as needed while the train is in a loop. My reason for converting to DCC is to eliminate all the blocks for parking trains and I would like to have a wireless handheld and simplify the wiring in general as the layout has a transient life.

My question, I intend to retain the EPL components to throw the loop switches as the trains leave the loops, and use the relays to flip the polatity under the train. Will this work without major problems? The relays that I am currently using are rated at 10A with a 25ms open and close times and again from what I have read online (both forums and manufactures) that response time is comparable to the loop controllers. Is that 25ms too fast or slow and should I consider adding gold caps to the decoders to cover the momentary loss of power?

I'm pretty sure that I'll need to run the EPL components off a separate power supply, not the DCC track power without a decoder, again is this correct? Also, the Massoth switch decoder is the only one I've found that has provisions for using switches or non-DCC systems in conjunction with a decoder.

Now, the only letters I can tack on to my name are BS, but from what I have been reading it should work. I'd rather spend money on a larger central station and decoders at the start than replacing bits that I already have that will do the job.

Thank you in advance for your comments.


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## toddalin (Jan 4, 2008)

Sounds like the way to do it to me without the need for short-circuit sensing (and the associated arcing and pitting, etc.). I don't know if 25 ms is too long a delay for the ??? DCC system that you may select, but if there is no short circuit, it should _probably_ work. I would think that any system that is well designed should be able to take a 25 ms break and remember what it was doing.
Good luck and let us know how it turns out.


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## mbendebba (Jan 22, 2011)

pdfx: 
If you were to setup a DCC system without the reverse loop configured as you have proposed, you would not need a sperate power supply to control you EPL components once you install switch decoders. You would need an external power source for lighting up switch lanterns or semaphore lights. Without stwitch decoders, an external power source would be needed to operate the switches, and lighting the accessories. 
I agree with toddalin that most DCC system these days are capable of tolerating 25ms break. however, I would not test that assertion on my equipment, particularly since a digital reverse loop module costs around $100, and a big DCC station could cost 10 to 15 times that much. 

Mohammed


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## krs (Feb 29, 2008)

Mohammed - 

I'm not sure what you were reading in pdfx's post when you say: 
If you were to setup a DCC system *without the reverse loop configured as you have proposed*, 

Didn't he clearly state: 
It is a loop to loop that uses EPL components and two relays to throw the loop switches and *reverse polarity of the three districts as needed while the train is in a loop*. 

To me that means he is running analogue, ie DC, right now and manages the reverse loops using EPL components and relays. 

If that is the case, I see no reason why he can't just continue to do this when converting to DCC. 

As to: 
you would not need a sperate power supply to control you EPL components once you install switch decoders 

Not a good idea to power EPL switches using DCC track power unless you have lots of current to spare. 
You can control the switches via DCC if you like and if that makes sense - questionable for a small layout in my opinion, but the power to actually throw the switches should not come from DCC track power. 

And as to the 25 msec relay times. 
The comment about that is a red herring in this situation. These are relay operate and release times which have no bearing on the polarity switching times - those are determined by the relay transfer time which is probably a millisecond or less depending on the contact configuration. 

And I don't really understand your last comment: 

I would not test that assertion on my equipment, particularly since a digital reverse loop module costs around $100, and a big DCC station could cost 10 to 15 times that much. 

Are you suggesting to buy a $100 Massoth reverse lopp module because the way reverse loops on this layoutare handles right now might destroy a $1500 Massoth Central station? 
That's what I read between the lines. 

Knut


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## mbendebba (Jan 22, 2011)

KRS: 
1) if I were to convert to DCC, I would take advantage of all that DCC has to offer, I would control the entire layout using DCC. 
(2) you may choose not to control epl switches using DCC, I would choose to control them using DCC, their power consumption is nil
(3) you need to read the actual lines, not what's between the lines. you should have read and quoted, the preface to that statment


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## pfdx (Jan 2, 2008)

Thank you for the comments so far. I should have stated in my first post that while I am keeping the three districts intact I intend to connect the DCC system directly to the center district and only flip the polarity of the loops. Part of my goal is to eliminate the majority of the wires running back and forth for the loop control so when I have to pack it up, and put it back together, it doesn't take a whole day to re-wire it. 

Eventually I would like to have the switches under DCC control, but with the inital cost of a central station, remote, decoders to 3 locomotives of around $2000 I'd like to try using what I already have first. The additional cost of two reverse loop controllers, at least two switch decoders that cost get higher in short order. Besides right now I rarely throw the loop switches to change the path because I have to stop and change the direction of the train to do so. Something that may change once I start using DCC.


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## mbendebba (Jan 22, 2011)

There is one additional point I would like to make. For me the purpose of a DCC system is to control multiple trains on a layout, at the same time, no matter how big or small is the layout. Small layout are the most challenging. In pdfx 's case, I would add a siding or 2 between the 2 loops and have at least 2, and maybe 3 trains going at the time. To accomplish uneventful operation of such a layout, the swithching tasks have to be given to the DCC system with the operator controlling the speeds and sounds of the locomotives. That's not easy to do, but it become impossible to do, if one were to worry manually throwing switches.


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## Greg Elmassian (Jan 3, 2008)

I'm going all relay, I threw out all my autoreversers and put in relays. As an added bonus, the arcing of 10 amps across the contacts helps light the layout at night. 

(by the way, the PSX-AR autoreverser also has outputs for switch machines to be thrown when polarity reversal is needed, i.e. you could automate your switch machine for the reversing loop) 

Greg


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## East Broad Top (Dec 29, 2007)

As an added bonus, the arcing of 10 amps across the contacts helps light the layout at night. 
I _knew_ you'd finally see the "light!" 

(Sorry, that was just too good to resist.) 

Later, 

K


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## krs (Feb 29, 2008)

Posted By mbendebba on 29 Jun 2011 01:56 PM 
KRS: 
1) if I were to convert to DCC, I would take advantage of all that DCC has to offer, I would control the entire layout using DCC. 
(2) you may choose not to control epl switches using DCC, I would choose to control them using DCC, their power consumption is nil
(3) you need to read the actual lines, not what's between the lines. you should have read and quoted, the preface to that statment 

Well Mohamed,

Looks like you either didn't read my post or don't understand it.
I said *controlling* the switches using DCC is fine if pfdx wants to spend the money on the DCC switch decoders, what is not so great is using DCC track power to actually *throw* the switches.

These switches take a surge of current every time they are activated, better to take the power from a separate power bus rather than the DCC power that runs the loco motor, lights, sound, smoke etc.

Somehow people forget about that.

And since I didn't do so well "reading between the lines", what did you mean by your statement:
particularly since a digital reverse loop module costs around $100, and a big DCC station could cost 10 to 15 times that much.


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## krs (Feb 29, 2008)

Posted By pfdx on 29 Jun 2011 02:44 PM 
Thank you for the comments so far. I should have stated in my first post that while I am keeping the three districts intact I intend to connect the DCC system directly to the center district and only flip the polarity of the loops. Part of my goal is to eliminate the majority of the wires running back and forth for the loop control so when I have to pack it up, and put it back together, it doesn't take a whole day to re-wire it. 

Eventually I would like to have the switches under DCC control, but with the inital cost of a central station, remote, decoders to 3 locomotives of around $2000 I'd like to try using what I already have first. The additional cost of two reverse loop controllers, at least two switch decoders that cost get higher in short order. Besides right now I rarely throw the loop switches to change the path because I have to stop and change the direction of the train to do so. Something that may change once I start using DCC.


If you need to take the layout down every once in a while and then put it back up again, yeah, then going DCC wherever you can makes sense.
But if you have your layout wired for DC right now so that the auxiliary contacts (and relays) on the switches control the reverse loops there is really no benefit to change all that immediately.
With DCC you no longer have to stop the train and change direction since direction is no longer controlled by track polarity.


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## krs (Feb 29, 2008)

Posted By Greg Elmassian on 29 Jun 2011 02:46 PM 
I'm going all relay, I threw out all my autoreversers and put in relays. As an added bonus, the arcing of 10 amps across the contacts helps light the layout at night. 

(by the way, the PSX-AR autoreverser also has outputs for switch machines to be thrown when polarity reversal is needed, i.e. you could automate your switch machine for the reversing loop) 

Greg 
Greg,

I realize you're being funny after several previous recent threads on MLS on similar subjects, but before people take you comments too seriously..............

The suggestion here is to just keep what already exists and move to DCC in reasonable steps that don't break the bank.
Nobody is talking about adding more relays.

And there will be no arcing across the relay contacts since there is no current flow when the relays switch polarity.

And finally - the PSX-AR will control Tortoise and dual-coil switch machines, in their instructions it says nothing about controlling EPL switch machines.
Maybe the PSX-AR can be programmed to handle EPL switch machines and maybe it can handle the current required, but there sure is no indication that this is possible reading their documentation.


Knut


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## mbendebba (Jan 22, 2011)

Posted By krs on 29 Jun 2011 08:28 PM 
Posted By mbendebba on 29 Jun 2011 01:56 PM 
KRS: 
1) if I were to convert to DCC, I would take advantage of all that DCC has to offer, I would control the entire layout using DCC. 
(2) you may choose not to control epl switches using DCC, I would choose to control them using DCC, their power consumption is nil
(3) you need to read the actual lines, not what's between the lines. you should have read and quoted, the preface to that statment 

Well Mohamed,

Looks like you either didn't read my post or don't understand it.
I said *controlling* the switches using DCC is fine if pfdx wants to spend the money on the DCC switch decoders, what is not so great is using DCC track power to actually *throw* the switches.

These switches take a surge of current every time they are activated, better to take the power from a separate power bus rather than the DCC power that runs the loco motor, lights, sound, smoke etc.

Somehow people forget about that.

And since I didn't do so well "reading between the lines", what did you mean by your statement:
particularly since a digital reverse loop module costs around $100, and a big DCC station could cost 10 to 15 times that much. 





Knut: what can I say, I am a little thick sometimes

Mohammed


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## Axel Tillmann (Jan 10, 2008)

Nobody asked what is actually trying to accomplish. In general going DCC is a good decission for many reasons. But is always important is to understand what the customer wants to accomplish and what his budget constrains are. And before we are 10A on the relay we need to ask what engine is he really running. My engines (LGB and Kiss) don't draw in my reversing loop more than 1A. And even if I woud double head I only would draw 2A (and Greg Lighting in car is at daytime overrated and at nighttime I enjoy my vino







).

And would someone educate me whats wrong using a 10A relay switching lets say 4A (or even 10A) lines? Aren't the rating of the relays designed to priceisly stay operational at that rating? Or did I misunderstand something here? Nonetheless nobody will run in an indoor layout 4 SD45 with 60 freight cars behind it









Now as far as the exisitng reversing loop goes, I am a little confused. In analog I typically solve for a single train the reversing problem by NOT switching the loop(s) but by switching the main track, otehrwsied you end up with two much switching.

If that was the existing applicaiton the desgin has to be different. Aslo it has to be pointed out that if something changes in the longest train configuration the loop has to get bigger, in order to absorb the entire train + the additional reaction time to switch the loop after triggering around.

So if budget is intially is the issue there isd nothing wrong with the "old" analog setup - first. Even keeping the switches analog controller is a viable option. As matter of fact I just read in a couple of European magazines that some hobbyists prefer a physical switchboardand some go to length to accomplish this via DCC. Doing this via DCC in you basement layout will only pay dividends if you are also looking at train automation via computer controller software, which requires that you use DCC decoders to accomplish this.

But why don't you tell us more about what your plans are?


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## krs (Feb 29, 2008)

Axel - 

I thought it was pretty clear what pfdx wants to accomplish. It's right in his second sentence of the original post: 
My reason for converting to DCC is to eliminate all the blocks for parking trains and I would like to have a wireless handheld and simplify the wiring in general as the layout has a transient life. 

And he explains the "transient life" a bit more in a later post. 

As to the relay with the 10 amp contacts, you have to have followed some other threads on MLS recently that Greg became rather frustrated with to relate to that. 

Anyway, if the set up now somehow provides for reverse loop in DC operation, and there are number of ways to accomplish that, changing the train control to DCC should not make any difference in that respect. 

Knut


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## pfdx (Jan 2, 2008)

Axel, 

I'll summarize some of what I hope to gain by converting to DCC. 

1. Wireless hand held throttle. The layout in on the floor in a 12x39 foot room I have 3-4 places i like to sit and watch things go round. Only 4 out of 12 switches have drives, two are automatic on the loops and the other two are behind furniture (which I will likely convert to DCC). I the remaining switches will keep the manual throws because I still have to uncouple the cars. Currently I'm running a LGB 51070 and while to would be possible to go wireless I'm not sure I want to go that route for cost and other reasons 

2. Simplify wiring. The relay driven polarity control isn't that bad but the seven isolated blocks to park locomotives and lighted cars that create the spaghetti and take up space for controls and wire runs. Oh, and cats, two of them. Nothing like having 12 pounds of fur ball convinced that the bundle of wires moved. Someday my wife may receive a nice calico muff as a gift... but moving on. If I have a handle on things I should be able to hook up the central station at one loop control use the rails to buss the track power to the other and power the other control from a wall block with minimal to no wires in between. 

3. Intuitive direction. I never guess right having to check where all the switches are gets old. Headlight control would be nice too. 

Locomotives, all LGB. two with factory MTS decoders, one decoder ready and two pre-DCC 2055's. If I make the jump I'll start with the two decoder equipped to limit my initial confusion. Then convert the decoder ready loco or add more sophisticated loop controls but converting the 2055's would be towards the end as they are going take some work. 

The biggest current draw is with the two 2055's and 5 lit coaches, but the two 2055's pulling 18 cars puts on a good load too. Neither train has tripped the circuit breaker but you can tell where the slope in the floor is. 

I've also thought about adding a second handheld to run two trains at once. Yes, Mohammed there is a passing siding between the loops, with a three track yard. Gomez Adams would have a blast! 

Sound? Undecided. I've been around steam and diesel for 20 years and my ear is tuned to what should and shouldn't be so to me even the high end systems sound like rubbish. But to me these are toys so I may opt for a sound decoder with a simple sound set to amuse the kids. 

BTW Axel, I've been meaning to call to find out if drive wheels for an LGB Chloe are available. I have one side on my wifes engine that is arc pitting and causing it to stutter. 

Thanks for the comments.


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## mbendebba (Jan 22, 2011)

Axel: 
Doing the switching via DCC pays dividends even when you are not involved in train automation via computer control software, particularly in the case smaller layout. The more trains you have to control on a small layout, the less time you have to control switching manually . I would bet that most people will have a thought time running 2 or 3 trains simultaneously on a loop to loop with a siding or 2 between the loops and managing the switches manually. DCC control of the switches would make such a layout much easier to handle. With a single train running throught such a layout, I would even consider spending the money on DCC, and most certain not a system that would cost a couple thousand of dollars. 

Mohammed


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## mbendebba (Jan 22, 2011)

pfdx: 
Ther is no question in my mind that you layout is the perfect candidate for DCC conversion. Once you are settled in with DCC, I will bet that you will even consider doing uncoupling via dcc as well. This stuff is addictive and it grows on you. Just take it in small calculated steps, as you are doing and see where it leads. I, like you, am not into sound either, but for the kids it is everything. I like to run my layout with 4 or 5 trains running at the same time, through changing routes, and the challenge is to have them complete their trips whitout incident, no computer involved-just me, the central station, and 1 or 2 remotes. I ran a hybrid layout for a least 2 years (dcc trains control, analog control for everything else) without a single mishap. You choice of a large central is very wise and with the number of locomotives and switches you have, you will definetly has plenty of power in reserve. Whichever central station you end buying, make sure that you power supply meet its maxiumum current requirements. 
Enjoy, 

Mohammed


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## Jim Agnew (Jan 2, 2008)

And finally - the PSX-AR will control Tortoise and dual-coil switch machines, in their instructions it says nothing about controlling EPL switch machines. 
Maybe the PSX-AR can be programmed to handle EPL switch machines and maybe it can handle the current required, but there sure is no indication that this is possible reading their documentation. 

Knut, you're correct the PSX-AR will not control EPL switch machines. I learned the hard way... $$.


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## krs (Feb 29, 2008)

Posted By Jim Agnew on 01 Jul 2011 12:03 PM 

You're correct the PSX-AR will not control EPL switch machines. I learned the hard way... $$. 

Thanks for the feedback, Jim.

If you still have a need to have the PSX-AR control an EPL switch machine you could use this circuit as a base:










Decoder output 1 and 2 would be the PSX-AR drive for the dual-coil switch machines, the decoder common of course the return path.

"Motorized switch" is of course the EPL drive. 


Requires that the PSX-AR can drive sufficient current and that the output can be a times 1 second (or so) pulse.

This schenatic is copied from the original DCC handbook.
I haven't tried it out but I see no reason why this wouldn't work if the PSX-AR meets the requirements I mentioned above. 


Knut


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