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Analog loop reversing relay

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Posted by Mark R. on Tuesday, March 23, 2021 12:13 PM

ATLANTIC CENTRAL

  

I have seen it in print and seen it in use before, works well if you can except those limitations.

I would have to dig thru a few old books that are currently packed up to find who published it.

Sheldon

 

Believe me, I wasn't laying claim to inventing the idea. Being so simple, surely somebody long before me had to have come up with it. But I will admit, I came up with it on my own without having seen it in print prior to.

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

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Posted by SeeYou190 on Tuesday, March 23, 2021 12:18 PM

Mark R.
Believe me, I wasn't laying claim to inventing the idea. Being so simple, surely somebody long before me had to have come up with it. But I will admit, I came up with it on my own without having seen it in print prior to.

I had also never seen it in print. One of the "old guys" at Scale Rails Of Southwest Florida suggested it to me as a simple solution on the club's N scale layout.

It works.

ATLANTIC CENTRAL
I have seen it in print and seen it in use before, works well if you can except those limitations. I would have to dig thru a few old books that are currently packed up to find who published it.

Expanding on this possible solution, I would suggest Dave do this to solve the problem:

This uses a bridge rectifier and a reversing DPDT switch (center-off if you want to park a train) to control train direction in the reversing section.

This is simple to control, and there is no need to stop the train. It is also fairly straightforward to build.

The biggest draw-back is that the train will slow in the reversing section a bit because of the voltage drop in the rectifier diodes.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Lastspikemike on Tuesday, March 23, 2021 2:21 PM

Turns out we've been at cross purposes. Dave is using snap switches (I.e Atlas turnouts they branded Snapswitch for some reason). 

The reversing switches in the one photo are Atlas Twin switches. 

The wiring schematic in the Atlas Wiring Book shows that the powerpack connections are made to the side terminals while the reversing loop and the main power are taken from the four terminaks across the top (oriented with the branding word readable). 

The upper side terminal connecting power from the powerpack (lets call it black) routes power to the left hand terminals of each pair  at the top of the switch. The other (red) connects to the two right hand terminals, again each pair. 

Allowing for the fact that the Twin Switches are mounted "upside down" which is perfectly ok,  I see that the wiring to the tracks is incorrect.

The first pair of wires of the four need to be swapped red for black. Right now the Twin Switch is wired as a dead short as soon as either the red button is slid in either direction.  Technically either pair of red and black can be swapped depending on which way the operator  to consider to be Up or East. 

The order of the wires is the top power wire (actually the bottom as oriented by Atlas) is red so the order of wires along the bottom of the Twin Switch (top as oriented by Atlas) should be black/red/black/red. According to the schematic. Unfortunately, the sketches in the Wiring Book do not clearly display the buttons on the Twin Switches. The schematic is clear. Assuming right way up for the Twin Switch the schematic shows power as upper side terminal connects to the left side of each pair in the four top terminals. 

Reverse order if you mount the switch upside down. Rofl. Get it. Reverse!

Alyth Yard

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Posted by Lastspikemike on Tuesday, March 23, 2021 2:39 PM

The photos show facing reversing loops which can get a little mind bending when wiring the Twin Switches. If you want individual control of polarity for each reversing loop, and usually you do, then the second twin switch is needed. But because of the Atlas powerpack  power flow through design you only need to connect the second reversing loop to the second Twin Switch. The other pair of terminals on the second Twin Switch is not used. You can wire the second Twin Switch backwards if you wish if you want all three red buttons to line up when running a train in one direction through the loops. East and West again. 

It is important to recognize that track power to main line only needs one Twin Switch connection (one pair of red and black). If you try to wire up the main line to both Twin Switches you'll get a dead short in one of the red button positions. 

It actually doesn't matter if you swap red and black on the reversing loop terminals. It really depends on which direction through the loop is "main" from the operator's perspective.  Atlas wires theirs In figure 2.6 as if the diverging route continues the main line, which frankly is a tad confusing. It is also arbitrary. The connections to the actual main line are determinative of East West direction. Reversing loop direction is arbitrary. 

Alyth Yard

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Posted by Dave K on Wednesday, March 24, 2021 11:06 AM

Still awaiting from others?

 

Dave

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Posted by Dave K on Wednesday, March 24, 2021 11:56 AM

I do not want to complicate thing with a bridge rectifier.  Just want to use a transformer and a twin switch for polarity reversal.

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Posted by SeeYou190 on Wednesday, March 24, 2021 5:16 PM

Dave K
I do not want to complicate thing with a bridge rectifier.  Just want to use a transformer and a twin switch for polarity reversal.

If you do not have the rectifier you will need to either stop the train in the reversing section, or flip the direction switch on the power pack and the DPDT to the reversing section simultaneously.

The reason for the rectifier is to allow the DPDT reversing switch to control the reverse section independent of the controller direction position. As the train goes through the reversing section the direction switch on the controller can be flipped without affecting the direction of the train in the reversing section.

This is simpler to control, which is a preference for me.

You would need a separate DPDT switch for each reverse section, but they could be supplied by the same rectifier.

When I build my layouts, I am OK with complicated builds in exchange for simple operation. You might hear the phrase "With DCC you control the train, but with DC you control the track", but, that does not need to be true.

I do not control the track, just the turnouts, which you need to do with DCC as well. The turnout position controls cab selection, signalling, isolation, and power routing.

As described previously, my reverse section has industries on it. All trains must stop and either pick up or drop off a freight car. The first direction change is done with the reverse section DPDT reversing switch. This makes control through the reversing section almost invisible.

There are almost no electrical controls on my panels other than turnout toggles. However, it is more difficult to build this way.

Reading about the Atlas Twin (which I have never used) it is supposedly just two DPDT reversing switches (not center-off) in a plastic housing. It is priced higher than a pair of DPDT Center Off Toggle switches, so I will never use one.

From how it looks to me... you could feed the Atlas Twin from the DC terminals on the recitifer, and use each side of the Atlas Twin to control a reversing section. Someone familiar with the Atlas products will need to verify that this is correct.

Also, another detail I am not sure about, but if the Atlas Twin is not "break before make", I would never consider using it.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by gregc on Thursday, March 25, 2021 6:00 AM

SeeYou190
If you do not have the rectifier you will need to either stop the train in the reversing section, or flip the direction switch on the power pack and the DPDT to the reversing section simultaneously.

i thought the common approach (Linn WestCott) is NOT to use the direction switch on the throttle and have separate reversing switches for the mainline and reversing section(s) connected to the throttle.   with separate mainline and reversing-section reversing-switches for each throttle a single reversing-switch can be used for all reversing sections.

with the reversing-section switch properly set to match the mainline polarity for the route entering the reversing-section, the mainline reversing-swith is toggled after the train completely enters the reversing section and the turnout switched so the train can re-enter the mainline from the reversing-section.

i don't understand the need for a "rectifier". (the reversing-section reversing-switch is connected to the throttle and is independent of the mainline polarity)

greg - Philadelphia & Reading / Reading

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Posted by ATLANTIC CENTRAL on Thursday, March 25, 2021 6:31 AM

gregc

 

 
SeeYou190
If you do not have the rectifier you will need to either stop the train in the reversing section, or flip the direction switch on the power pack and the DPDT to the reversing section simultaneously.

 

i thought the common approach (Linn WestCott) is NOT to use the direction switch on the throttle and have separate reversing switches for the mainline and reversing section(s) connected to the throttle.   with separate mainline and reversing-section reversing-switches for each throttle a single reversing-switch can be used for all reversing sections.

with the reversing-section switch properly set to match the mainline polarity for the route entering the reversing-section, the mainline reversing-swith is toggled after the train completely enters the reversing section and the turnout switched so the train can re-enter the mainline from the reversing-section.

i don't understand the need for a "rectifier". (the reversing-section reversing-switch is connected to the throttle and is independent of the mainline polarity)

 

Actually it is/was common DC practice to use all three reversing switches.

Using the added main and reverse loop switches as "system" switches and using the power pack or throttle switch to change direction during actual switching moves, etc.

A few post back is an explanation of the rectifier approach, a whole different way to control a reverse loop with its own set of limitations.

Sheldon

    

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Posted by Dave K on Thursday, March 25, 2021 7:21 AM

To begin with, neither of my Atlas twin switches work.  I used a DVM to check output voltage and polarity from both.  I applied voltage to the input terminals and measured output on each switch in the three possible positions.  Very erratic output.  Going to go with simple DPDT 6 post switches.

 

Dave

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Posted by Lastspikemike on Thursday, March 25, 2021 10:30 AM

The latest Atlas product is made in China. I bought a 220 controller which was completely dud right out of the packaging. I took my multimeter to the same hobby shop to test a second brand new one out of the sane shipment before buying, in order  to save a trip. Tested the circuits as per Atlas schematic right in front of the store Owner. Complete dud as well. The problem seems to be in the spring switch aspect of the plastic sliders. The electrical contact clearance (air gap) inside the switch must be tiny and if the plastic mouldings are poor there's no way they can build them consistently to work properly.  

Atlas Made in the USA switches work really well, even when quite old. Current Atlas QA leaves a lot to be desired apparently. 

Atlas Twin Switch replaces the function of the powerpack reversing switch. For common rail designs I think you need to use the reversing switches closest to the track power and not use the powerpack reversing switch at all. 

Alyth Yard

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Posted by SeeYou190 on Thursday, March 25, 2021 10:50 AM

gregc
i thought the common approach (Linn WestCott) is NOT to use the direction switch on the throttle and have separate reversing switches for the mainline and reversing section(s) connected to the throttle. 

Yes, That was the approach that Linn Wescott promoted. When he suggested this, walkaround DC throttles did not exist, and this approach was easier.

With walkaround DC throttles, having a seperate mainline and reverse loop direction switches became less practical.

The OP wanted simple, and I just put out one option that is simple to control and fairly easy to build.

Dave K
Going to go with simple DPDT 6 post switches.

That sounds like a good idea.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by gregc on Thursday, March 25, 2021 12:04 PM

all of the ideas discussed in this thread would make a good chapter in Best Book about Wiring a Layout

greg - Philadelphia & Reading / Reading

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Posted by ATLANTIC CENTRAL on Thursday, March 25, 2021 2:16 PM

gregc

all of the ideas discussed in this thread would make a good chapter in Best Book about Wiring a Layout

 

Years ago I started writing a book about my Advanced Cab Control system, and advanced DC ideas in general. Then life got busy again and it sits unfinished.

Sheldon

    

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Posted by Dave K on Thursday, March 25, 2021 2:17 PM

I will return the Atlas junk.  I purchased four DPDT switches to control my two turnbacks.

 

Dave

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Posted by ATLANTIC CENTRAL on Thursday, March 25, 2021 7:29 PM

Lastspikemike

The latest Atlas product is made in China. I bought a 220 controller which was completely dud right out of the packaging. I took my multimeter to the same hobby shop to test a second brand new one out of the sane shipment before buying, in order  to save a trip. Tested the circuits as per Atlas schematic right in front of the store Owner. Complete dud as well. The problem seems to be in the spring switch aspect of the plastic sliders. The electrical contact clearance (air gap) inside the switch must be tiny and if the plastic mouldings are poor there's no way they can build them consistently to work properly.  

Atlas Made in the USA switches work really well, even when quite old. Current Atlas QA leaves a lot to be desired apparently. 

Atlas Twin Switch replaces the function of the powerpack reversing switch. For common rail designs I think you need to use the reversing switches closest to the track power and not use the powerpack reversing switch at all. 

 

As much as I am a fan of Atlas track, I have never cared for their wiring devices or their promoted wiring system, even back in the 70's when I worked in the hobby shop.

Sheldon 

    

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Posted by SeeYou190 on Thursday, March 25, 2021 8:11 PM

gregc
All of the ideas discussed in this thread would make a good chapter in Best Book about Wiring a Layout

Greg, one of the items I think people should ask themselves when deciding to use DC or DCC to control a layout is if they have enough DC knowledge to design, install, and troubleshoot the system all by themselves.

There are just too few people left that can help with complex DC systems, and the books, all written decades ago, were for a different audience.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by ATLANTIC CENTRAL on Thursday, March 25, 2021 9:13 PM

SeeYou190

 

 
gregc
All of the ideas discussed in this thread would make a good chapter in Best Book about Wiring a Layout

 

Greg, one of the items I think people should ask themselves when deciding to use DC or DCC to control a layout is if they have enough DC knowledge to design, install, and troubleshoot the system all by themselves.

There are just too few people left that can help with complex DC systems, and the books, all written decades ago, were for a different audience.

-Kevin

 

That's partly why I started to write a book, and maybe one day I will finish it, after the layout is built.

This was a bad week for construction progress here at home, but this weekend looks promising.

Kevin, it sounds like you and I use a lot of similar wiring methods, one day after the pandemic we must get together in person.

Sheldon

    

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Posted by SeeYou190 on Thursday, March 25, 2021 9:18 PM

ATLANTIC CENTRAL
Kevin, it sounds like you and I use a lot of similar wiring methods, one day after the pandemic we must get together in person.

We share a great many similarities.

1954, no Big-Boys, DC control, private roadnames, no foam, etc.

I would love to meet up if there is ever another Timonium show!

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Dave K on Friday, March 26, 2021 9:06 AM

Guys,

 

My other hobby is restore Chevy Corvettes so I have plenty of knowlege with simple 12volt systems.  I do not consider my layout with two turnbacks to be complex.  I have been away from model railroading for a long while and need to catch up on the electric side.

 

Dave

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Posted by ATLANTIC CENTRAL on Friday, March 26, 2021 2:04 PM

Dave K

Guys,

 

My other hobby is restore Chevy Corvettes so I have plenty of knowlege with simple 12volt systems.  I do not consider my layout with two turnbacks to be complex.  I have been away from model railroading for a long while and need to catch up on the electric side.

 

Dave

 

No worries, everyone is just trying to understand both what you have, and what your goals are.

I'm pretty deep into some really advanced DC, with wireless throttles, signals, detection, one button route control. I never assume a correct answer until I know what I'm dealing with, so I tried to just let the others help - mostly.

I'm a car guy from way back, worked on a lot od Chevy's, and other stuff.

Restored and built this little hot rod in 1976:

1963 Nova SS convertible - only made that year, never made with a V8 but easily converted with 64 and later parts.

283, Corvette heads and cam, Torker, 600 Holley with vac secondaries, headers/Corvair turbo duals, 4 speed - and a unique drive line that worked well for such a light car - M20 with the low 1st gear, 3.08:1 rear axle.

Enough starting ratio, but lots of top end. 

0-60 - 5.5 sec

1/4 mile - under 14 sec

Top end - my 160 mph Corvette speedo said 135 mph and it was still pulling in 4th gear - that was fast enough in the little unibody convertible.

Fuel economy - driven like you had any sense - 20 mpg highway

Today I just drive a factory hot rod of sorts - 2015 FORD FLEX LIMITED w/ecoboost - almost the same performance stats as the Nova......

Had lots of other hot roads over the years.......

Sheldon

    

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Posted by Lastspikemike on Friday, March 26, 2021 7:01 PM

Dave K

Guys,

 

My other hobby is restore Chevy Corvettes so I have plenty of knowlege with simple 12volt systems.  I do not consider my layout with two turnbacks to be complex.  I have been away from model railroading for a long while and need to catch up on the electric side.

 

Dave

 

It's not. Red and black. The main challenge is presented by reversing loops (any alignment that may connect the red rail to the black rail.) So you need to isolate both rails at both ends of any track that might switch polarity of a rail to the wrong one. Then devise a switching system to reverse polarity at the correct time as your train traverses the loop. Quite easy to arrange with a little thought. 

You had it figured out and Atlas let you down. 

Plus it seems none of us were alert to what your difficulty actually was. Sorry about that.

 

Alyth Yard

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Posted by Lastspikemike on Friday, March 26, 2021 7:05 PM

Dave K

I will return the Atlas junk.  I purchased four DPDT switches to control my two turnbacks.

 

Dave

 

You'll probably be fine just using three of those. It can be done with only two depending on how many trains you want to run and in which directions through the loops. The section you choose to be the "main" line needs only one polarity reversing switch. 

Alyth Yard

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Posted by SeeYou190 on Friday, March 26, 2021 7:26 PM

Lastspikemike
Plus it seems none of us were alert to what your difficulty actually was. Sorry about that.

So now you are speaking for the group?

Confused

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Lastspikemike on Saturday, March 27, 2021 8:35 AM

SeeYou190

 

 
Lastspikemike
Plus it seems none of us were alert to what your difficulty actually was. Sorry about that.

 

So now you are speaking for the group?

Confused

-Kevin

 

Nope. Pointing out the obvious. 

Double checking the thread and the third post is the correct reponse to the question actually being asked, had we but known.

Fortunately, the OP figured this out despite all the helpful suggestions about solutions to a different problem. 

Alyth Yard

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Posted by Dave K on Saturday, March 27, 2021 10:20 AM

This is a great forum and I like everyone's help.  I will stay connected as I am sure to have more questions.

Dave

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Posted by Dave K on Wednesday, March 31, 2021 9:24 AM

I have installed two DPDT (center off) switches.  One for the main track and on for the gapped turnback.  What is the process to reveres the polarity as the train leaves the main line, enters thr turnback and leaves turnback back on to main line?

Regards

Dave K.

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Posted by Lastspikemike on Wednesday, March 31, 2021 2:44 PM

Match polarity as the train enters the reversing section, wait until the entire train is within the reversing section (assuming metal wheels at the tail end car or pusher loco) then throw the polarity on the main before your train exits the reversing section.  You do not need to stop the train despite what some people still think is necessary. 

Reversing sections are like a three dimensional Möbius strip. The left rail becomes the right rail somewhere around the reversing loop. By flipping polarity of the main line you match the main line polarity to what is now the new right rail polarity within the loop. It's the movement of the train around the loop that creates the need to reverse polarity on the main line.

The outside rail of the loop connects the left and right raiks of the main line at the turnout. The inside rails of the reversing loop  are a discrete loop of nickel silver not connected to the main line at all. That's why you need isolating gaps and separate power to the reversing loop.  

The confusing part comes from the fact that the rails don't change so you don't really notice the left rail crossing over to connect with the right rail. Thinking about it is harder than just running a finger over the outside rail around the reversing loop and considering the fact that your finger does not change polarity. So, polarity must change electrically.

I just realized that an ME turnout forming a reversing loop only needs power to

the inside rail, no gaps are needed on that inside rail and only the outside rails (stock rails) need gaps. Cool.  The frog rails are dead on an ME turnout. 

Alyth Yard

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Posted by SeeYou190 on Wednesday, March 31, 2021 2:52 PM

Dave K
What is the process to reveres the polarity as the train leaves the main line, enters thr turnback and leaves turnback back on to main line?

Dave,

I am starting a new thread.

Stand by...

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Dave K on Thursday, April 15, 2021 10:01 AM

I gave up n the two DPDT switches to control the turnback and have gone back to one.  Still having difficulty synchronizing the DPDT switch when the train leaves the block and enters the main line.  

Dave

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