Wiring DBL Slip

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The information having to do with frog polarity reversal is irrelevant to Peco InsulFrog turnouts. The information about track connecting to the slip having the correct polarity is applicable to any slip, no matter how itís made or who makes it.

A slip (single or double) has two frogs. For an ElectroFrog slip to work, polarities must come to the slip correctly, and the frogs needs to have individual polarity reversing capability. In most cases itís all fairly easy to do - especially with DCC. There are four wires coming from the bottom side of the double slip - one from each frog. The wires are imbedded in groves in the ties.

A slip, single or double, requires certain things for it to work. This includes polarities being correct, and a way to reverse the polarities of the frogs when needed. Whether itís a single or double slip is irrelevant when it comes to polarities. They are both installed and handled in the exact same way. The only difference is that there is only one slip to allow transition from one route to the other. Regardless, both frogs and all routes have to be considered. Weíll first show how a double slip needs to be installed, then explain how to deal with polarities.

Illustration 1 shows the rails that are fed by each feeder wire. The two blue frogs are separate, each with its own feeder. The red indicates the rails that are fed by the feeder going to the top stock rail, while the green shows the rails fed by the bottom stock rail feeder. The frog feeder wires must be used to control the frog polarity, and insulated rail joiners must be used to connect the adjoining rail to them.



The stock rail feeders can be used to power the stock rails, or the stock rails can be connected directly to the adjoining rails with metal rail joiners. There are four wires (feeders) coming from the Peco ElectroFrog Slip: one from each frog, and one from each stock rail.




Illustration 2 shows that the polarity of the rails joining to the slip must match the polarity of the slipís stock rails.



You can see that this will be connecting both polarities to each frog, which is why those rails must be connected with insulated rail joiners.

If using DCC, there are two ways to control the polarities of these frogs: auto-reversing, or external contacts connected to each throw bar.

If using auto-reversing, you can use two Digitrax Auto-Reversers (D-AR1) or two of the four outputs of a Digitrax PM-42 (D-PM42). If using the D-AR1, connect one output of one D-AR1 to one frog, and one output of the second D-AR1 to the other frog. If using a PM42, connect one wire of one output to one frog, and one wire from the second output to the other frog. It doesnít matter which output wire you use, as long as you use a separate auto-reverser for each frog. In any case, it will auto-reverse when a short circuit is sensed at either frog.



If using external contacts, you have to realize that the throw bar on one end of the slip needs to control the frog on the other end of the slip. Illustration 3 shows how to do that.



This could be Peco contacts mounted on a Peco switch motor, a SPDT micro switch mounted to make contact with the throw bar, or any other common Single Pole Double Throw (SPDT) device. When the throw bar is one way, it feeds power from Rail A,; when set the other way it feeds power from Rail B.



Illustration 4 shows a situation that will have to be corrected before you can make the slip work correctly.



Notice that the track coming into the double slip from the upper right doesnít have the correct polarity. This means that you have a reverse section somewhere on the layout that hasnít been resolved, and will not work. To fix this, you need to go back on that rail and install a reverse section so that the polarity comes into the slip correctly.

There are many variations of this, but regardless of what the situation is, the polarity must match as shown in Illustration 2 above. Note that it doesnít matter what the polarity is as long as it matches in all directions. Once it matches, resolve the frog polarity as described above.

Again, with Peco InsulFrog Slips, you do not have to be concerned about reversing the polarity of the frogs. But you do have to be sure the polarity of tracks attached to the slip is correct.

Illustration 5 shows you how to wire your double slip switch using Tortoise contacts to route the power to the rails properly and adding LED indicators 



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Last modified:  May 23, 2016