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PostPosted: Mon Aug 01, 2011 2:05 pm 
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Location: Port Dover, Ontario
Hi,

Andy Tait submitted a full set of schematics that illustrate how to wire a double crossover using four Tortoise switch machines. Wiring a double crossover is a bit complex and can be confusing for some (OK most) modelers, which is why a lot opt to use the new Frog Juicers available from us.

Following the schematics posted below will show you how to wire a double crossover to automatically switch the polarity of the frogs based on the route selected. This will work for both DC and DCC on a double crossover with isolated frogs.

I have also included an animated version that shows what happens to the polarity of each of the four isolated frogs when the routes are changed from Normal (all straight), route 1 to 4 (cross over one direction) and route 2 to 3 (crossover other direction).

There are always and only three possible routes when using a double crossover. Normal, which is all turnouts switched for a straight route. Reversed 1 to 4, which is turnout 1 and 4 switched to crossover (diverging), or Reversed 2 to 3, which is turnout 2 and 3 switched to crossover (diverging). It is not electrically possible when using switched frogs wired from a turnout to have all turnouts set to crossover, this will create a dead short, one or the other routes have to be selected. This can be done when using a Frog Juicer however.

Switch Machine Standards

Image
For large version of above image, click here


Wiring Diagram

Image
For large version of above image, click here

Use this diagram to wire a double crossover using four Tortoise switch machines. The contacts on the machines are numbered 1 thru 8, the same as on the drawing. A feeder is run from each of these contacts to either another contact on the machine, another machine, or fed to the rail shown in the diagram. Some contacts will require two wires to be attached to it. Rail gaps are shown on the diagram and must be on the double crossover in the same locations.


Animated Schematic

Image

Watch closely as the double crossover is switched. The color (polarity) of each frog changes relative to the route selected. The switch points and switch machine contacts move indicating the route through the crossover.

Schematic showing routes through crossover
These are the individual images that make up the animated image above.

Image
For large version of above image, click here

Image
For large version of above image, click here

Image
For large version of above image, click here

Thanks very much to Andy for producing these for us!

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Tim Warris
Fast Tracks
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PostPosted: Tue Aug 02, 2011 8:44 am 
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Location: Melbourne, Australia
Very clear and simple diagrams. What more could you want?

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PostPosted: Sat Sep 17, 2011 9:20 am 
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jdm_com_au wrote:
Very clear and simple diagrams. What more could you want?


Since you asked :) ...

Maybe this is obvious to a more experienced modeler, but I'm unclear how best to connect the wiring shown here to a control panel.

Seems like maybe some sort of 3-position switch (knob or slider) would be better than individual toggles for the turnoutsl, but then how are the wires from the switch positions tied in to the tortoise wiring as diagrammed?


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PostPosted: Sun Sep 18, 2011 12:15 am 
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It could be done several ways. I will be using a series of 4 pole, 3 throw rotary switches and probably a handfull of diodes. It will mean more complicated wiring, but simpler switching. I do not know what would be simple or difficult for you, so I may not be able to give the best answer. I am also untested at creating drawn images as shown above, so I would also be unable to give even the simplest of schematics.

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PostPosted: Sun Sep 18, 2011 1:24 pm 
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Although it is probably not prototypical, but ............ a double crossover has basicly only two valid settings:
- all routes straight
- all routes diverting

This could ease your configuration.

Having said this, in the prototype they probably just pulled the points which were "the wrong way for the next train" and would leave all the other points "as is".

So if you want to run prototypical, use the complicated version. If KISS apllies ..........

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PostPosted: Wed Apr 25, 2012 7:43 pm 
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Location: Port Dover, Ontario
Hi,

The issue with selecting "all routes straight, or all routes diverging" is that all routes diverging will create a dead short with powered frogs. With all routes diverging, the frogs are required to be both polarity at the same time, creating the short, so only one cross route can be selected at one time.

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PostPosted: Tue May 01, 2012 12:54 pm 
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Location: Oklahoma City, OK
I may be the old fashion type, but one way to set controls in a panel is with push buttons and a power capacitor supply. You would only need four buttons, one for each straight route and one for each crossing route. You would simply wire the out put from the push buttons to power the two switches needed for the selected route, leaving all others as is.

With this method you would have to double check route setting as you approched the double crossover to make sure your route is selected by puting the one button you need.

Using a capicator style power supply you get enough power to throw the switches and then it recharges for the next set.

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PostPosted: Wed May 23, 2012 7:09 am 
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The switching can be done using only 2 dpdt switches as you will need to throw at least 2 points any way why not throw them from the same switch.

Connect 1 switch to two motors that form the crossover route for one direction, and the other switch to the other 2 motors forming the route for the other direction, easy.

If your doing dcc simply connect to 2 motors that form one crossover to the same decoder output if your decoder can handle the load of 2 motors, and then connect the other 2 motors to another out put, making sure the throw direction the mated motors is matched. IE:- close position or thrown position, and not 1 closed and 1 thrown.

I use Digitrax DS64 decoder and have had no problems with it perfoming this task.

It might be possible to even give 2 out puts the same addres # to split the load on the decoder (check your manuals for this as I am not sure)

You could even do the combo ddc with the manual switches as well.

Cheers
Ray


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PostPosted: Fri Jun 15, 2012 6:35 am 
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Hi all!

I am about to wire all turnouts and the big issue is the double crossover (with live frogs) whose ends have 4 double slips. All turnouts in the layout (Tillig and Weller) have live frogs.
As I am planning to use small servo motors to shift the point blades, this is my question:
should the servo motors directly be connected to a digital decoder (such as Uhlembrock's or ESU's, for instance) that does not provide any polarity and then should the polarity of the 6 frogs be provided by 1 big frog juicer?
Would this scheme work in your opinion?

I am asking as, the classic scheme with double slips would be different:
the servo motors would be connected to the digital decoder that provides the correct polarity to the frogs (and in this case I must use a turnout decoder that also provides polarity).

With a double crossover, the servo motors would still be connected to a digital decoder, but the polarity would only be provided by the juicer. Wouldn'it?
And it seems to me this scheme is fully valid for DCC operations (I would like my layout to be DCC-ready) but not for analog ones.
Unfortunately, as I still have some locomotives without decoder, how can I feed the frogs in analog mode?
I know for sure that, in order to avoid troubles, all analog locomotives will not be allowed to enter the double crossover (DCC operated) but at least, I would like them to go through the double slips.
What happens to the frogs in analog mode? Can they still be polarized by the decoders? Or shall I find another option?

Thanks for your help!!!

Pierre


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PostPosted: Fri Jun 15, 2012 10:55 am 
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Location: East Texas - USA
The frog juicer will not work in DC mode. Even having a juicer connected with DC applied would likely burn up the juicer . . . especially if activated by a short.

Wire each double slip up independently, using standard double slip wiring activated by the points throw. Double slip portion should follow the methods described here and use contacts activated by points throw. You don't have to use Tortoise machines, but you need the equivalent electrical contacts activated by some limit switches from movement of the points throw.

Of course, going ONLY DCC would make it much simpler. There is simply no free lunches.

-ed-

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PostPosted: Sat Jun 16, 2012 5:07 pm 
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Thank you!

I actually suspected the frog juicers could not be used in analog mode: therefeore I will make the double crossover only DCC-friendly and all non-analog engines will avoid it. I have already set 1 track (adjacent to the double crossover) that will allow analog locomotives to enter the main station...whenever it is necessary.

Regards,

Pierre


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PostPosted: Tue Apr 16, 2013 5:41 pm 
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Location: Oklahoma City, OK
How much different would wiring be using the switches with Bull Frogs. I know you would have to switch each turnout manually, but you only have two choices of wire routing.


Kurt :?

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PostPosted: Thu Apr 18, 2013 12:50 pm 
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Hello Kurt,

Although it's not prototypical to control a double crossover manually it's technically feasible with the BullFrog switch machines using 2 micro switches mounted on each of them. Simply replicate the wiring for the Tortoise machines that use contacts 2 through 7 and orient them the same way on the micro switches, where one switch would be contacts 2, 3 and 4 while the other is 5, 6 and 7.

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