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 Post subject: Double Crossover wiring
PostPosted: Thu Sep 07, 2006 3:34 pm 
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Joined: Mon Nov 14, 2005 8:50 pm
Posts: 73
Location: Cassville, MO
Does anyone have a working schematic for a HO double crossover (built on a fast tracks fixture) and using tortoise machines?????

I am having problems getting it figured out!

Thanks


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PostPosted: Fri Sep 08, 2006 11:45 pm 
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Joined: Mon Nov 21, 2005 9:28 pm
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littletree wrote:
Does anyone have a working schematic for a HO double crossover (built on a fast tracks fixture) and using tortoise machines?????

I am having problems getting it figured out!
No kidding! I have the same problem. It looks like we have 4 "frogs" to deal with. The problem is that different combinations of polarity are required depending on which way you go through. I believe using it as an "X" is out. It would require the red and blue pieces to be dead or a short would happen. So you can (for the sake of discussion) go through straight on either track, from the lower left to upper right or upper left to lower right. Straight through is no problem. The others are! If you look at the colored scan I attached, to go from lower left to upper right, the left rail on entry needs the blue and yellow rail to match it and the right needs the cyan and red. If you go from upper left to lower right the left rail needs the yellow (same as the other way) but now you need the RED to match the left rail. The same flip happens to the right rail, instead of cyan and red, it needs cyan and BLUE. This assumes that the two main lines are electrically parallel.

The big problem is that the thing needs two DIFFERENT polarity swaps to take place for each route through. For the lower left to upper right, the cyan rail needs to change polarity to match the right rail and so does the red. The blue and yellow must match the left rail. In other words, if the left rail is +, then the blue and yellow must also be + and the cyan and red must be - to match the right rail.

LL to UR left = +, blu = +, yel = +, cyn = -, red = -
UL to LR left = +, blu = -, yel = +, cyn = -, red = +
Straight left = + blu = +/-, yel = -, cyn = +, red = +/-

I don't see a good way to change these areas to 3 different combinations. You might be able to make it work with Tortoise points AND a reverse loop card(?). Or do I need more coffee?

Jim


Attachments:
File comment: Double crossover with polarities marked (crudely)
polarity.jpg
polarity.jpg [ 82.21 KiB | Viewed 13977 times ]
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 Post subject:
PostPosted: Mon Sep 11, 2006 2:55 pm 
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Joined: Mon Nov 14, 2005 8:50 pm
Posts: 73
Location: Cassville, MO
Thanks for the info Jim, I had not thought about the reversing card. I have considered auxilary relays but still have not came up with anything, on paper, that looks like it will work.

Thanks again!

Anyone else have info? The hobby really needs a solution other than "dead frogs" on the R-O-W.


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 Post subject:
PostPosted: Mon Sep 11, 2006 7:56 pm 
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littletree wrote:
Thanks for the info Jim, I had not thought about the reversing card.

I "think" that a reversing card on the BLU and RED frogs, combined with Tortoise swapping of the YEL and CYAN, has a good chance of working. The BLU and RED only get hiit when the thing is diverted from the main line. The card will deal with the polarity and, since the left and right rails have the same polarity for any given route through, the cards short length reverse district shouldn't be an issue. You'd still need two sets of points from at least one Tortoise to swap the other two (CYN and YEL). Since I use ine set of points for C/MRI status, I'd need to swap the CYN with one Tort and the YEL with the diagonally opposed one. That's OK, because they should never be set differently.

You DO need to be sure that you somehow interlock them so that you don't make an "X" crossing. If you do, you create a dead short at the CYN and YEL sections. That's an issue I have to address somehow, as although my system has computer control (C/MRI) it doesn't "wake up" with its' brains attached and the first thing I have to do in the program is check occupancy (don't want to move an occupied turnout) and then set all my turnouts to a known configuration. As the track power has to be on to check occupancy, and as the thing comes up more or less set randomly, I stand an excellent chance of a dead short on powerup. That, I have to solve. I may have to dedicate a latching relay and an output port to enable Tort-switched track power to only one set of two Torts at a time. That way, if it comes up goofy, only one way through is energized.

It seems to me that by adding a few ties with strategic cuts, the RED and BLU regions could at least be made a good deal shorter. That way, the need for a reversing card woul be a great deal smaller. The length of dead frog would be much shorter.

Jim


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 Post subject:
PostPosted: Tue Sep 12, 2006 9:15 pm 
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Joined: Fri May 07, 2004 11:22 pm
Posts: 311
Location: Port Dover, Ontario
Hi All,

I wired up one of these for my layout last year, and as I recall, they are nasty things to figure out!

Unfortunately I can not remember how I did it, and at the moment I am not at home (the one with the layout) and can not say exactly how it was done. I did get it to work using 4 Tortoises and I believe a few additional relays. Once I am back at the layout I will have a closer look and make up a sketch on how it was done.

I do recall thinking this could be done easily with an automatic reversing module like Digitraxs' PM42, but have not confirmed this.

Sorry I can't be of more help, yet....

_________________
Cheers!

Tim Warris
Fast Tracks
http://www.fast-tracks.net
service@fast-tracks.net


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 Post subject:
PostPosted: Wed Sep 13, 2006 10:31 pm 
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Joined: Mon Nov 14, 2005 8:50 pm
Posts: 73
Location: Cassville, MO
Thanks for the posts! Mabey we can get something that will work nicely and post it for all the people in this hobby that can use it.

I have what I think will work, I used one DPDT 12V DC relay to control two areas with. The actuators are Tortoise. They are interlocked such that only one crossing route can be selected at a time. There may be two things that are missing - the NON selected crossing route leads are not "dead" and there are no contacts left for signalling. This can be corrected using two more relays or Torts.

Here are the drawings. Anyone, let me know if there is a problem with them - they are UNTRIED. Should be easy to adapt this to DCC. The drawings are electrically identical - the three scans just show the 3 possible routes selected, color coded to show polarity and contact positions for each route.

Thanks,
littletree


Attachments:
2nd #8 double crossover wiring - straight thru routes selected.jpg
2nd #8 double crossover wiring - straight thru routes selected.jpg [ 220.33 KiB | Viewed 13712 times ]
2nd #8 double crossover wiring - crossover route 1 selected.jpg
2nd #8 double crossover wiring - crossover route 1 selected.jpg [ 229.58 KiB | Viewed 13697 times ]
2nd #8 double crossover wiring - crossover route 2 selected.jpg
2nd #8 double crossover wiring - crossover route 2 selected.jpg [ 225.13 KiB | Viewed 13683 times ]
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PostPosted: Mon Sep 18, 2006 4:22 pm 
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Joined: Mon Nov 21, 2005 9:28 pm
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I believe that this will work as a possible DCC configuration. It has the restriction that it must be set to all straight through or all diverted. A single crossover configuration would cause a hard short. It should work fine with a $24 reversing unit. The need for interlocking is eliminated from an electrical standpoint. It is necessary to provide for "power up symmetry". By doing all the polarity switching from one pair of Tortoises, the possibility of a hard short on powerup due to Tortoises being out of sync is eliminated.

I think.

Jim


Attachments:
File comment: Assumes parallel tracks are the same polarity!
MAIN.jpg
MAIN.jpg [ 206.69 KiB | Viewed 13940 times ]
DIVERTED.jpg
DIVERTED.jpg [ 240.28 KiB | Viewed 13931 times ]
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 Post subject:
PostPosted: Tue Sep 19, 2006 4:25 pm 
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Joined: Mon Nov 14, 2005 8:50 pm
Posts: 73
Location: Cassville, MO
Thanks for the input - we are getting the info out to all the other hobbyists that need it! How does all the wiring interconnect for the DCC ready method you describe? Does the reversing module operate automatically via tortoises or something else, or require operator input?

Since this requires both tracks to be the same polarity, this would not work for DC Analog. Correct?

Thanks again, lets keep hammering this out and mabey the final results can be included in Fast Tracks general information for us customers!

Ron/Tim - any thoughts about doing that?

littletree


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 Post subject:
PostPosted: Tue Sep 19, 2006 4:43 pm 
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Joined: Mon Nov 21, 2005 9:28 pm
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littletree wrote:
Thanks for the input - we are getting the info out to all the other hobbyists that need it! How does all the wiring interconnect for the DCC ready method you describe? Does the reversing module operate automatically via tortoises or something else, or require operator input?
The reversing module is totally automatic but only works with DCC. You just connect one output from the module to each rail and it flips the polarity instantly when it sees a short. The Tortoises each have 2 sets of points. I used one set each from 2 Tortoises. You hook the normal "right rail" to one point, the "left" rail to the other and as the Tortoise moves, the 3rd connection is switched to whichever output you need. They're break before make. Hooked up properly, the wire from the Tortoise to the turnout frog will always be correct.

Sorry! I happen to run DCC, so my part is solved, I think.

Jim


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 Post subject:
PostPosted: Wed Sep 20, 2006 5:10 pm 
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Joined: Mon Nov 14, 2005 8:50 pm
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Location: Cassville, MO
Jim - Looks and sounds great! I have dealt mostly with DC Analog, but want to go to DCC. I beleive what I posted will work fine for either, with some small changes for DCC (mostly where the track power comes from). Your description of an automatic reversing module usage seems even simpler than my DC method, I am going to try both to see.

I have copied your drawings and comments to a file for future use.

If anyone else tries the DC Analog drawings, I would appreciate some feedback - good or bad.

Everything we do is a learning experience.

Thanks to all.


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PostPosted: Thu Dec 21, 2006 10:22 pm 
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roadkill_97006 wrote:
It is necessary to provide for "power up symmetry". By doing all the polarity switching from one pair of Tortoises, the possibility of a hard short on powerup due to Tortoises being out of sync is eliminated.
I have the solution for the power up problem. I use C/MRI to control my layout (block detection, turnout control, signals) - and specifically I use the SMC-12 cards to drive the turnouts. I do this so that I can use a local bypass switch if the computer is sick or for testing, and because it's easier to have all the Tortoises wired the same way (and if you get it wrong, all you need to do is swap two wires at the board and the Tortoise runs the other way).

http://www.jlcenterprises.net/Products.htm#Controller
If you look at the picture, the screws on the bottom would be the input screws and the pairs of screws at the top go to the Tortoises.

If you use the SMC-12 to drive the Tortoises and wire the inputs in common so that only one wire to the SMC-12 controls all 4 Tortoises, then the problem is solved because they will always be driven the same way on power-up by the SMC-12, regardless of whether the computer is running or not. In fact all you need to switch a Tortoise with this board is 5V or ground connected to the input to make a Tortoise run one way or the other. Easy for anyone, even if you don't do computer control. The board supplies the Tortoise power, so there's no way they can ever get out of sync, and thus they can never cause a short.

Jim


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 Post subject:
PostPosted: Fri Dec 22, 2006 5:23 pm 
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Location: Cassville, MO
Thanks for this information. It may take me a while to digest it, I haven't done any computerization of a layout yet. Looks interesting, particularily the ability to use this w/o a computer connected.

Thanks again,
littletree


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 Post subject:
PostPosted: Fri Dec 22, 2006 5:51 pm 
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littletree wrote:
Thanks for this information. It may take me a while to digest it, I haven't done any computerization of a layout yet. Looks interesting, particularily the ability to use this w/o a computer connected.
One thing I forgot to mention is that the board is designed to be sliced up into two-Tortoise chunks. So you don't have to have 12 in any one place to make use of it. I've got them spotted right in the middle of a bunch of Tortoises so as to cut down on wires. It only takes one wire from the panel to the board to make a Tortoise work. They also put out enough current to drive two Tortoises from one side of one chip, so you really can run 12 pairs, if you want to - and by swapping which wire goes to which side of a given Tortoise from the board, the two Tortoises of a pair don't even have to run the same way! Good stuff.

Jim


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PostPosted: Tue Dec 26, 2006 1:37 pm 
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roadkill_97006 wrote:
I believe that this will work as a possible DCC configuration. It has the restriction that it must be set to all straight through or all diverted. A single crossover configuration would cause a hard short. It should work fine with a $24 reversing unit.
OK. I finally put the thing in service and it works great. I went with the DCC Specialties OG-AR unit, as it's solid state and this is on my main line. Two of the Tortoises switch the remaining center sections. All 4 Tortoises are simultaneously driven by an SMC-12 card as I discussed before. Even a little switcher with one bad pickup will creep right through. No relays, simple wires. :D

Jim


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 Post subject:
PostPosted: Wed Apr 18, 2007 7:24 am 
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Joined: Wed Apr 18, 2007 7:05 am
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Location: Morth Plains, OR
Not sure about the drive current of the SMC-12 but if you are using 4 switch machines why not drive the other three of them with the DPDT switch in the first one. This would give you an effective 6PDT switch to use for the other functions at no cost.

I am using a mechanical linkage to control all four sets of points so it is not an issue for me. The "wire" is 0.030 copper plated wire feed welding wire that solders very easily to a piece of rail for the "push rod".

Image
Image
Image


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