# Figure 8



## tbar (Jan 26, 2009)

Looking to run a figure 8 switched from a outer loop with 4 10' wide AC switches,to inside of loop to a 19.5 AC cross-over, using DC power. I put a UBoat on and put power to it and blew a fuse on the TE receiver,twice. Any ideas out there??? Thanks


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## Greg Elmassian (Jan 3, 2008)

Yeah, but I've got so many ideas it's too much to type!!! 

Seriously: 

Did the U boat move at all... does it run ok when it moves, have you run it on straight DC, is it a trackside TE, what voltage input, what size fuse.... 

There's a few questions that will help narrow it down. 

Regards, Greg


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## kormsen (Oct 27, 2009)

if it is a figure 8 made with switches from a circle or ovaloid, you created two short circuits. no way, how that could work, save the use of insulated rail joiners at both diagonals.


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## aceinspp (Jan 2, 2008)

Sounds like a reverse loop in the works and a short has now been created. Later RJD


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## Greg Elmassian (Jan 3, 2008)

I thought the Aristo crossing just was wired like 2 straight through pieces of track? 

A figure 8 should be ok. 

Dunno... 

Grfeg


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## wchasr (Jan 2, 2008)

Greg, I think the point being with 4 switches to create the figure 8 from the oval he's created a reverse loop or rather 4 reverse loops. Recognizing it I can do wiring it? Not my bag of chips. Sorry I can't help. 

Chas


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## Greg Elmassian (Jan 3, 2008)

You are dead right, missed the part of loop to figure 8... 

This is serious reversing loop stuff. If he connected the figure 8 to the outer loop at one end only I think he is ok... 

Regards, Greg


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## tbar (Jan 26, 2009)

THANKS to all.....at work today I thought also about the reverse loop, and the possible short.....I have heard there's ways to get around it, is this true????...Greg, Uboat runs fine on DC , just tried it here, and no it didn't move at all, just blew the fuses. The TE receiver is the ART-5471 with a 10 amp fuse, that is what it uses, as far as I know. It's worked fine before. Haven't checked voltage. I power the receiver with a Crest Ultima 10 amp power supply.


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## Greg Elmassian (Jan 3, 2008)

Yep the others got right to it, I overlooked the part about the figure 8 in a loop. 

If you want the same track plan, you will have to wire up what is used for reversing loops and put insulated joints in the right place. 

I would recommend a different track plan first. With the setup you have, if a train is on the outer loop, then you cannot run a train on the figure 8 and vice versa. This problem combined with the reversing loop wiring nightmare would cause me to reconsider and make a track plan with no reversing loops and the ability to run 2 locos at the same time without it looking like the addams family! 






















Regards, Greg


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## toddalin (Jan 4, 2008)

Does it happen as soon as you turn on the power _even without a train on the track_ (direct short) or only when you put the train on, and then _if it gets to a particular spot_ (induced short)?


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## tbar (Jan 26, 2009)

toddalin, it blows the fuse shortly after I hold the button on the transmitter down with an engine on the track, it dosen't move....and for everybody...I broke track connections between the switches on each side of the loop, and the figure 8 runs great. Would still like to figure out how to run loop and the 8.....Greg, only ONE train would run on this loop/8 combo.


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## Greg Elmassian (Jan 3, 2008)

OK, reverse loop seems to be confirmed. 

The problem you will have is basically (and there's different ways to solve the problem) when going to/from the figure 8 to/from the loop, you have a reverse loop situation. 

You could isolate the 2 "legs" of the outer loop as reversing loops and use some electronics to automatically switch the track polarity. 

Luckily, there are things you can buy off the shelf to do this, although I don't mess with them since I run DCC and it's simpler. 

Also, you have Todd here, who is an expert in figuring out this stuff, so he will probably come up with a number of solutions. 

I guess I would put a Massoth autoreverser on the figure 8, and then isolate the 2 lobes of the outer loop. You will still have to be careful not to have super long trains, I believe. 

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 08 Jul 2010 04:38 PM 
OK, reverse loop seems to be confirmed. 

Also, you have Todd here, who is an expert in figuring out this stuff, so he will probably come up with a number of solutions. 


Regards, Greg 

We need to see a copy of your track plan to best assess how to address the situation. It may be easiest to draw it out and scan it.


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## tbar (Jan 26, 2009)

OK , on copy of track plan.....don't see a place for attachment here, of a drawn plan in my computer.


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## toddalin (Jan 4, 2008)

Posted By tbar on 08 Jul 2010 06:20 PM 
OK , on copy of track plan.....don't see a place for attachment here, of a drawn plan in my computer. 







You need to have the plan stored somewhere on the internet on a server. Or, you can e-mail it to me and I can probably put it on the net.

[email protected]


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## kormsen (Oct 27, 2009)

tbar, 
do you want to run around the loop in both directions, or just always in the same? 
how long is the straight between the switches in relation to your trainlength?


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## tbar (Jan 26, 2009)

kormen, i'd like to run both ways...but what ever works...theres 4 to 6 ft of track between the switches....train length can vary


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## tbar (Jan 26, 2009)

OK, toddalin...e-mail on way, thanks


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## wchasr (Jan 2, 2008)

Greg, 
I'd never known what the Addams family layout looked like! That's awesome! Thansk for posting that! 

Tbar, 
Looks like you've got some "expert" help now that things are getting clearer as to what you are doing. Looking forward to see the answers myself too. 

Chas


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## toddalin (Jan 4, 2008)

This is the track plan that Tbar sent me last night. As you can see it is not a single reversing loop, but four simultaneous reversing loops with four simultaneous points of short circuit. Looking at the plan, a couple relatively simple solutions present themselves to me, but there are a couple caveats.

Before I post my solution, I would like to hear from others who may also have a solution. Maybe they could solve the caveats I've encountered and I don't want to sway anyone's _free thinking_ on this.


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## toddalin (Jan 4, 2008)

Tbar,

I don't know your level of experience in large scale or background in electrical wiring. Are you familiar with the standard LGB components and how they work (i.e., turnout motor, supplementary switch, and track insulators)? If I/we simply describe a solution could you follow it (some here could), or will I/we need to do drawings for you?

Thanks,

Todd


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## DougArcher (Jan 2, 2008)

how about battery power?


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## Greg Elmassian (Jan 3, 2008)

How about unhelpful suggestion? 

Greg


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## tbar (Jan 26, 2009)

toddalin.....that would be a negative, on this scale of electronics....anything basic, is all I can master at this time.....I'll need the MOST info, with the drawings , I'm not to up on LGB...only got a couple cars.....FYI...I did some more playing...like I said before....I broke track sections between the switches on each side of the loop and a UBoat run fine on the "8".....what I also found out is when I touched track sections on one side together, real quick, so I wouldn't blow a fuse, the UBoat stopped....Thanks


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## vsmith (Jan 2, 2008)

Posted By toddalin on 09 Jul 2010 10:34 AM 
This is the track plan that Tbar sent me last night. As you can see it is not a single reversing loop, but four simultaneous reversing loops with four simultaneous points of short circuit. Looking at the plan, a couple relatively simple solutions present themselves to me, but there are a couple caveats.

Before I post my solution, I would like to hear from others who may also have a solution. Maybe they could solve the caveats I've encountered and I don't want to sway anyone's _free thinking_ on this.








http://www.largescaleonline.com/eim.../Tbard.jpg />


This layout only works on 3-rail O where the track is AC powered. otherwise is reverse loop spaghetti fest of wiring and swithes, suggest the easiest solution would be to make it a simple figure 8.


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## toddalin (Jan 4, 2008)

OK, this is really so simple as to be ridiculous. (I like a challange.) But it does go to show that practically anything can be done using simple track power with a little "engine-uity."

I, or anyone familiar with LGB stuff will instantly see what's going on here and once you grasp the concept we can help you with the build if so desired. I use the LGB turnout motors on my AristoCraft 10-foot turnouts and you can too. I'll put the diagram in this post and discuss it further in the next. Once a diagram is posted on this web site, if you try to edit that post, your diagram is destroyed/lost.


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## toddalin (Jan 4, 2008)

The red and black lines represent the wires from your power pack that go to the track. They also go to what appears to be a double pole, double throw (dpdt) switch. That "switch" is actually the LGB dpdt supplementary switch (EPL) that attaches to the back of that LGB turnout motor. To make this work and ensure that there are no short circuits we will use four LGB turnout motors. (I think we could also use the AristoCraft turnout motors with some modification to the circuit, but this is far simpler.)

We will use one momentary, four pole, double throw (4pdt), center off, toggle switch to simultaneously throw all four turnouts either to the "O" or the "8" position. This is not shown in the diagram nor are the turnout motors, but is common LGB practice and once the rest of the circuit makes sense, we can discuss how this is done using a couple diodes and a/c power source if you opt to go this route.

The four orange lines represent LGB/AristoCraft track insulators. You will need two packs of four and the eight are arranged as shown just off the ends of the turnouts.

The CAVEATS!

The train must be short enough to fit on the curved section of track between the two turnouts where the power supply is connected. This is because when you throw the turnouts, they will all throw at once and you don't want wheels fouling the turnout.

If you change the turnouts from the "O" to "8" or vice versa when the train is anywhere except between the above two turnouts, the train will start running backwards. This is not a bad thing and will keep you from accidently crossing the wrong gap and shorting out power pack blowing the fuse.

So, if you can live with those requisites, this is probably the easiet and cheapest way to go.

Todd


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## Greg Elmassian (Jan 3, 2008)

Pardon the dumb question, but of course you replicated the circuit on the other "wye", right? 

By the way, to avoid "disappearing stuff" when editing... you can go into the HTML view, and add some blank lines in the proper spot so as not to type "into" some existing code... the tinymce editor seems to do it on this forum. 

It's especially helpful with quoted text. 

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 09 Jul 2010 03:56 PM 
Pardon the dumb question, but of course you replicated the circuit on the other "wye", right? 

By the way, to avoid "disappearing stuff" when editing... you can go into the HTML view, and add some blank lines in the proper spot so as not to type "into" some existing code... the tinymce editor seems to do it on this forum. 

It's especially helpful with quoted text. 

Regards, Greg 


I am assuming that the "crossover" is a simple 30* crossing and not an LGB double slip switch. That being the case, I think the circuit is complete as is. Maybe I'm missing what you are getting at? I'm seeing this as four reverse loops and not seeing a wye per se.


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## Greg Elmassian (Jan 3, 2008)

Oh, I did not see where you put insulators... is the "hatched area" isolated? Four locations where insulated joiners (8 counting both rails) are? 

If that is so, I understand. 

Thanks, Greg


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## toddalin (Jan 4, 2008)

Let's Take a Ride!

OK, lets take a ride through the figure. We will place the train on the left side of the layout between the turnouts where the power enters the track and place our train to run clockwise.

For the first run, well take the outside loop (O). We throw the turnouts and all four throw toward the straight path to make the train follow the “O” path. This is actually the position of the EPL dpdt as shown in the illustration. As the train goes around, the polarity to the inner and outer rails don’t change. When the train gets to the turnout at the bottom left, it crosses the insulator and is still in sync so there are no short circuits. The fact that electricity also runs though the X is of no consequence as there are no trains there and the insulators keep this electricity from getting through the turnouts.

Once the trains is between the turnouts we throw the turnouts to the “8” position and all four turnouts move to their diverging paths. The EPL is also thrown simultaneously with the turnouts as it is mounted to the turnout motor and now routes power to the upper left portion of the “X.” The train proceeds though the “X” and into the area between the two right side turnouts. But this is also in sync with the “X” and the train proceeds around through the top right turnout through the diverging path back toward the “X” and finally back to the lower left turnout, and finally back to the left side between the turnouts. The fact that electricity also runs though the O is of no consequence as there are no trains there and the insulators keep this electricity from getting through the turnouts.

As I noted, if a train is anywhere other that on the left side between the turnouts, it will reverse direction when the turnouts are thrown. This would then keep you from crossing the insulators in the event that the turnout is thrown when the trains is not on the left side between the turnouts.

If we want the trains to change direction and run counterclockwise and it associated “8,” we can do that too.

When the train is between the two turnouts on the left we stop it and throw the turnouts for the “O” position, if that’s not how they were set. We then _back_ the train through the two lower turnouts into the area between the two turnouts on the right. If we then throw the turnouts to the “8” position, the train reverses direction and now it is headed _forward_ again, but this time the other direction through the “8” and “O.”


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## Greg Elmassian (Jan 3, 2008)

When I started my post, your second post (the one after the one with the drawing) was not up yet... so was not able to read and look for the orange lines... 

I took a while to complete the post, got distracted by something else... so now the explanatory post is there... was wondering why you were already talking about editing the post. 

Perfectly clear. 

Thanks, Greg


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## tbar (Jan 26, 2009)

Thanks again Todd.....will go with throwing the switches manually for now...tackle the motors down the road...will go w/LGB, as I understand they're better for outside also....when it dries up here, I'll try the wiring in the diagram.....I got 2 12v (auto)rocker switches, with center off...is that OK?...got to get some track insulaters too...I won't mess with diagram...also the cross-over is a AC 19.5...


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## toddalin (Jan 4, 2008)

Posted By tbar on 09 Jul 2010 06:27 PM 
Thanks again Todd.....will go with throwing the switches manually for now...tackle the motors down the road...will go w/LGB, as I understand they're better for outside also....when it dries up here, I'll try the wiring in the diagram.....I got 2 12v (auto)rocker switches, with center off...is that OK?...got to get some track insulaters too...I won't mess with diagram...also the cross-over is a AC 19.5... 

Assuming that you hand throw the necessary turnouts, you could certainly replace the LGB EPL dpdt with a simple dpdt switch (not center off) and wire it up just as shown. To go clockwise, you would need to hand thow the upper left and the lower right turnout and put the switch in the position shown for the "O" to made "O's" and upper left and upper right turnouts and put the switch in the "8" position to make "8's." The wheels _should_ push the other two turnouts into place or you can just throw them all by hand.

To go counterclockwise, you would need to hand throw the lower left and upper right turnouts and put the toggle switch in the "O" position to make "O's" and the lower left and lower right turnouts and put the switch in the "8" positions for "8's" or just throw them all as necessary.

It's really that easy but you can see why the automation makes it easier.

I would NOT use two spdt switches to replace the dpdt switch because unless you throw them both at the same time, each time, you'll create a short circuit and pop your fuse.


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## tbar (Jan 26, 2009)

Todd,..first....that was quite a "ride"...had to read it a few times..make sure I got it right...what I meant by not messing with diagram ..was I won't try to edit it...just don't want to lose it and your other post...will it stay here..or should I copy it....like I said before....got some down pours here...be a little bit before I can get out there....got that on the DPDT switch, and have to get that to....just 2 more questions...are those AC 10' switch and the AC 19.5 cross over insulated to prevent any problems??.. and can you show the wiring to the DPDT switch??...also put some electrical grease on the wiring and connections on the under side of switches/crossover, to help against moisture.


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## Greg Elmassian (Jan 3, 2008)

Silicon caulking on the connections would be better than grease... clear silicon will let you know if any corrosion is happening. Just put it on the places where the tin-plated copper wires connect to stainless steel screws. Dissimilar metals in water will equal corrosion or galvanic action. Grease can become displaced.

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By tbar on 10 Jul 2010 05:40 AM 
Todd,..first....that was quite a "ride"...had to read it a few times..make sure I got it right...what I meant by not messing with diagram ..was I won't try to edit it...just don't want to lose it and your other post...will it stay here..or should I copy it....like I said before....got some down pours here...be a little bit before I can get out there....got that on the DPDT switch, and have to get that to....just 2 more questions...are those AC 10' switch and the AC 19.5 cross over insulated to prevent any problems??.. and can you show the wiring to the DPDT switch??...also put some electrical grease on the wiring and connections on the under side of switches/crossover, to help against moisture. 

The AC crossings and turnouts should be fine as they are so long as you install the 8 insulators as shown in the diagram.

The wiring to the dpdt switch is _exactly as shown in the drawing_. Nothing changes and if you decide to automate this in the future using the four LGB turnout motors and the one LGB EPL dpdt that mounts to the turnout motor, the track/EPL wiring is exactly as shown except that the EPL _is_ the dpdt switch. The only wiring that will change will be the addition of some wiring to power the LGB turnout motors, but it's not necessary for manual throws. The EPL _IS _just a dpdt switch that moves with the turnout instead of having to move it by hand.

BTW, off topic, look for my railroad on page 66 of this month's (August) _Garden Railways_ Magazine.


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## Greg Elmassian (Jan 3, 2008)

Todd, even after I read to look for the orange lines, I can see only 4, 2 on each switch on the "left side" of the crossing.So 8 refers to 2 insulators per line I guess.


Sorry, just want to be completely clear, you did not explicitly come back when I asked early on if the "hatched area" was the isolated area. Of course the right end of the 8 is not hatched.


I played with your diagram a bit so I can follow more easily. It sure looks like a simple, elegant solution.











Regards, Greg


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## tbar (Jan 26, 2009)

Thanks again Todd...just drying out here....plus, need to pick up switch and insulators...then we'll give it a try...keep you posted here.


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 10 Jul 2010 10:36 AM 
Todd, even after I read to look for the orange lines, I can see only 4, 2 on each switch on the "left side" of the crossing.So 8 refers to 2 insulators per line I guess.


Sorry, just want to be completely clear, you did not explicitly come back when I asked early on if the "hatched area" was the isolated area. Of course the right end of the 8 is not hatched.


I played with your diagram a bit so I can follow more easily. It sure looks like a simple, elegant solution.











Regards, Greg 





Yeah, you've got it. Two packs of 4 for a total of 8 insulators. My orange lines did not come through very well, but note that they do go all the way through both rails. The crosshatch is the ties in the original drawing from Tbar.

Thanks for the complement. I know it's ego talking, but I just love it when a dozen people say it can't be done, or easily, and it only takes a little thought, a few insulators, and a switch.


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## Greg Elmassian (Jan 3, 2008)

Well, I'll throw another one at you while you head is a couple sizes larger ha ha! 

I'm glad you understand that I want to understand. I look forward to your solutions, because they are always "reduced down" to the minimum components and maximum simplicity. 

As an engineer, that's always been a design goal that evokes respect and admiration. 

Regards, Greg


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## toddalin (Jan 4, 2008)

Tbar,

When you get your DPDT switch and are ready to wire it it, you don't really need to send two set of wires to two different places on the track on the "right side" of the insulators. If you think about it, this whole section is connected electrically and all you are really doing when switching from the "O" to the "8" is reversing the direction of the current that is flowing to this entire right-side section.

In actually, you can just reverse the direction of the current right at the DPDT switch and then only send the wires to the topmost portion of the "O" as shown. (You still need all of the 8 insulators in the track.) This saves you wire and the necessity of either soldering wires to the track in two areas (rather than one) or buying two sets of connectors (4 connectors) rather than one set (2 connectors) for the "right side" of the track beyond the insulators When you want the train to take the "8" just flip the DPDT switch to reverse the direction of the power going to the topmost portion of the "O" as shown in the prior diagram.

The following diagram shows how you would wire up the DPDT or LGB Supplemental ELP switch to reverse the durrent. The wires come from the power pack on the left and go to the track toward the bottom right of the diagram.


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## Axel Tillmann (Jan 10, 2008)

Sorry for potentially throwing a monkey wrench into this.







But I can't see why this solution works - or let me rephrase works for a continued layout. Let me explain why:

Prelude:
The Switch with the DPDT is for my explanation A. and then clock wise switches are B, C, D (which is the other switch with insulation)

Here we go:
Train goes over A into the figure 8 and leaves figure 8 over C, goes straight on B and approaches A on the outer loop. Now what? You switch A to straight which now matches the "Main" polarity, but now your train goes backwards?

So is the requirement (I may have not seen that) that the train can only go back into the figure 8? Of course that works, but is limiting to what options you can do with the layout - And of course no second train on the track allowed.

While upfront costs may be prohibitive, but in DCC this is a no brainer. 1 Reversing Loop module on the inner figure 8, the figure 8 insulated from the the out loop. Done. As many trains on the track as you like, all switches controlled by the same system. Additional function, sound and engine controls .....


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## tbar (Jan 26, 2009)

OK Todd, I'll try the "1 2wire hookup" on top part of the "O", between the switches....to the rt of the insulators,...as per diagram...looks like I'll have to order insulators...get back to you


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## toddalin (Jan 4, 2008)

Posted By Axel Tillmann on 11 Jul 2010 04:05 AM 
Sorry for potentially throwing a monkey wrench into this.







But I can't see why this solution works - or let me rephrase works for a continued layout. Let me explain why:

Prelude:
The Switch with the DPDT is for my explanation A. and then clock wise switches are B, C, D (which is the other switch with insulation)

Here we go:
Train goes over A into the figure 8 and leaves figure 8 over C, goes straight on B and approaches A on the outer loop. Now what? You switch A to straight which now matches the "Main" polarity, but now your train goes backwards?

So is the requirement (I may have not seen that) that the train can only go back into the figure 8? Of course that works, but is limiting to what options you can do with the layout - And of course no second train on the track allowed.

While upfront costs may be prohibitive, but in DCC this is a no brainer. 1 Reversing Loop module on the inner figure 8, the figure 8 insulated from the the out loop. Done. As many trains on the track as you like, all switches controlled by the same system. Additional function, sound and engine controls .....










As I noted, _all four turnouts are thown simultaneously_. 

" Train goes over A into the figure 8 and leaves figure 8 over C, goes straight on B and approaches A on the outer loop. Now what?"

This doesn't happen.

Train goes over A into the figure 8 and leaves figure 8 over C, goes straight on B and *approaches D* (not A) on the outer loop. For the train to approach A would require that turnout B is set to the straight, rather than to the diverging path. If the operator purposely throws the four turnouts while the train is between B and C, it will run backwards, as I had noted. So, when he throws the turnouts to go in the direction you indicate, he could also reverse the current at his power pack to keep the train running in the right direction.

With some thought, I could add a simple "detector" to determine whether the train is on the "right" of "left" side of the layout and whether it needs to reverse polarity at the power pack to match the DPDT to keep the trains running in the same direction, but this would be way beyond the experience level of the original poster. (Remember I asked for input to aid in the caveats but no one came forth?)

As for no second train, that too could be done with a little more thought, and probably a couple caveats. But, that is not the intent or goal of the original poster who stated that this is only to be used by one train at a time and run in the manner that I've prescribed. 

Furthermore, even with DCC, I would like to see a simple wiring plan that would accomplish these goals and allow two or more trains to run simultaneously. I imagine that too could get "dicey." What happens when both trains simultaneously bridge gaps of opposite polarity (it would happen eventually), etc.?

Is that really any simpler or more effective? Maybe..., but not my field of expertise.

Additionally, while I never see it mentioned, DCC, and any form of power that allows the train to continue on its heading with a reversal of current to the rails, presents its own set of problems, many of which are for more difficult to fix. Any piece of polarity sensitive rolling stock or track accessory will be rendered "screwy."

Say I'm not made of money and don't want to put sound units in all my DCC engines, I can easily mount an analog sound unit in a trailing car and pull it behind anything. Cheap and easy. So if my engine is DCC and I cross a gap that requires track current reveral, my train now blows signals like it's going backwards? (Actually, I guess it wouldn't even work except to think the train is continually going an "Run 8.")









I cross a gap and now the directional signals on my caboose are backwards even though the train is still heading forwards?

My sheep are very amourous. If I only want the sheep in my stock car to "mate" when the train is going backwards and I use track power, I just pick up power from the track and wire in a diode. So, now with DCC every time I cross a gap my sheep have an orgy?

With a simple 555 chip/relay I can setup a reversing unit in my control panel and have _any engine_ automatically reverse between any two back-to-back sidings anywhere on the railroad because they all have diode protection. It's that simple. I've no idea if/how you could do this with DCC but it I can't imagine that it would be be that easy.

The list goes on, but is off topic here.

I guess it all comes down to how you want to run your trains, and while DCC may be great for those who are serious about operations, I would bet that most of us just "kick back" and watch them run, occasionally changing their courses, and for that, as well as $$$ savings, it's hard to beat old fashioned analog track power.


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## Greg Elmassian (Jan 3, 2008)

I did not point this out before, but Todd is right, using DCC there are restrictions on train length and of course bridging the insulated gaps at the same time. 

If the trains are any length at all, then you might re-think which sections you would isolate and probably still have to restrict train length. 


Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By Axel Tillmann on 11 Jul 2010 04:05 AM 
Sorry for potentially throwing a monkey wrench into this.







But I can't see why this solution works - or let me rephrase works for a continued layout. Let me explain why:

Prelude:
The Switch with the DPDT is for my explanation A. and then clock wise switches are B, C, D (which is the other switch with insulation)

Here we go:
Train goes over A into the figure 8 and leaves figure 8 over C, goes straight on B and approaches A on the outer loop. Now what? You switch A to straight which now matches the "Main" polarity, but now your train goes backwards?




Actually, if this is automated, this is a cinch and no detectors are necessary. If you can follow this:

Rather than using one turnout toggle for "O" or "8", we give each turnout its own toggle as is standard practice. Each toggle operates all 4 turnouts such that if any is toggled to one pattern or the other, all turnouts toggle to that pattern by default. A fifth LGB turnout motor and EPL is added that is only connected to the two turnouts on the right, B and C. This motor only triggers the EPL and is only wired to work with the two turnouts on the right. The EPL simply reverses the current to the left side of the diagram before the EPL take-off.

Now,

Train goes over A into the figure 8 and leaves figure 8 over C, goes straight on B. Train would normally go to D by default, but the operator toggles B to go straight though the "O" rather than take the the "8". All turnouts are toggled to the "O" position and the current is reversed. Normally this is when the train would start running backwards.

But the current to the entire system is reversed by the fifth turnout motor/EPL. So the current that was reversed by the EPL is re-reversed by the second EPL and the train continues straight. Furthermore, when the train reaches the section between A and D, its current has also been reversed so it now matches this other direction of travel.

Train proceeds through the left section, and if nothing is toggled proceeds to C through the last selected "O" pattern and continues around in the circle.

If the operator toggles turnout D when the train is in the section between A and D, the EPL mounted on turnout A properly reverses the current and the train proceeds to B, then C back to A (by default) and the polarity is correct throughout the path. If the operator toggles C from the "8" to the "O" when the train is between B and C, the would toggle the EPL on turnout A and again, this is where the trains would begin to run backwards. However, turnout C also throws the fifth turnout motor/EPL to the other direction and this re-reverses the current so the trains don't run backward and restores the original direction of current though the left section.

Piece of cake.


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## Axel Tillmann (Jan 10, 2008)

Greg:

Using the same design as above would almost eliminate the legnth problem, since you can't be any longer than "bumping" into yourself (last car still on the crossing, while engine(s) approach crossing. As far als Multitrain operation goes, you can actually circumvent length restrictions by using three short DCC reversing segments. This method is actually used on a triangular intersection.


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## Greg Elmassian (Jan 3, 2008)

Posted By Greg Elmassian on 11 Jul 2010 12:18 PM 
I did not point this out before, but Todd is right, using DCC there are restrictions on train length and of course bridging the insulated gaps at the same time. 

If the trains are any length at all, then you might re-think which sections you would isolate and probably still have to restrict train length. 


Regards, Greg Right, I believe I said that in my previous post, 1st sentence refers to using one DCC autoreverser.

Second sentence is self explanatory, the re-think part is what you just mentioned.

Was trying to compare apples to apples. I'd be spending more money for more autoreversers. Todd's solution is elegant and saves $$ with a few restrictions.

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By Axel Tillmann on 12 Jul 2010 07:39 AM 
Greg:

"Using the same design as above..."



If you use my latest design (note the addition of the fifth turnout motor/EPL) continuous running is possible without stopping or having trains run in reverse and it doesn't matter if you run DCC or simple track power as no autoreversers would be necessary for DCC because it is all taken care of through the turnout switching.









One of the "beauties" of track power is that if you can make it work with simple track power (and with some thought you typically can), it will in _all probability work with any __system_ simply by pluging in the appropriate piece of equipment to the track to replace the analog "throttle." 

Can any other system make that claim?


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## tbar (Jan 26, 2009)

Todd...got my track insulators and installed them as per diagram...also wired everything...the only thing I did different was the power to the DPDT...I tied in at the upper left track switch, at the clamps (insulators on the ohter side)....put on the AC Uboat...put power to it and run it though the "O"...with the toggle on the DPDT "down". Then when the engine was to the left of the lower left track switch...I threw the upper left and upper right track switch to the figure 8...along with fllipping the DPDT switch "up"....and..yup, people, ...the uboat walked though that, too,...not skipping a beat...no blown fuse either.....I want to give MANY THANKS to you , Todd, for being patient with me with this, and solving my problem.


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## toddalin (Jan 4, 2008)

Posted By tbar on 16 Jul 2010 07:16 AM 
Todd...got my track insulators and installed them as per diagram...also wired everything...the only thing I did different was the power to the DPDT...I tied in at the upper left track switch, at the clamps (insulators on the ohter side)....put on the AC Uboat...put power to it and run it though the "O"...with the toggle on the DPDT "down". Then when the engine was to the left of the lower left track switch...I threw the upper left and upper right track switch to the figure 8...along with fllipping the DPDT switch "up"....and..yup, people, ...the uboat walked though that, too,...not skipping a beat...no blown fuse either.....I want to give MANY THANKS to you , Todd, for being patient with me with this, and solving my problem. 


I'm so glad it worked out for you. When you are ready to move on, we'll take this to the next step (full automation).


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## tbar (Jan 26, 2009)

OK, Todd, in the mean time, I'm still getting a kick out of people scratching there head on this one....thanks


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## tbar (Jan 26, 2009)

OK, Todd, in the mean time, I'm still getting a kick out of people scratching there head on this one....thanks


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## toddalin (Jan 4, 2008)

Posted By tbar on 18 Jul 2010 07:25 AM 
OK, Todd, in the mean time, I'm still getting a kick out of people scratching there head on this one....thanks 



Gotta love it!


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