Crossovers with Unifrog

[IKB 1985]

I know that Unifrog has been discussed on here, I've read a huge amount of what there is but as a total newbie to model railways I'm really struggling here. After reading the various bits I understood Unifrog was the "best of both worlds" but it's become clear that contrary to what I had (perhaps foolishly) believed there is no isolation when the blades are flipped. For sidings this is no big deal, an isolating section will cure that but what is frying my brain is crossovers. How do you wire these? Insulating rail joiners will leave the area beyond the points dead, surely I don't need two isolating sections either side of the points? Any guidance would be much appreciated as electrics aren't a strong point and this is proving a very steep learning curve!

Edited February 23 by IKB 1985
Typo

[Dominion]

If the cross over is made from 2 Peco unifrog turnouts and if the 2 parallel tracks are intended to use the same power feed as each other, then you can just use metal joiners on both rails. 
This is because the diverging rails beyond the unifrog are already connected to their appropriate stock rail within each Peco unifrog turnout.

Edited February 24 by Dominion

[IKB 1985]

3 hours ago, Dominion said:

If the cross over is made from 2 Peco unifrog turnouts and if the 2 parallel tracks are intended to use the same power feed as each other, then you can just use metal joiners on both rails. 
This is because the diverging rails beyond the unifrog are already connected to their appropriate stock rail within each Peco unifrog turnout.

Thanks mate, but unfortunately they're not. The crossover is between two loops that should be independently powered. I'm just a bit bemused how the track behind the points is still energised.

[Dominion]

If you want the loops independently powered then use insulated joiners between the 2 turnouts.

If you want then to be on different power zones then use 2. If you want them on the same power zone but just independently switchable you could use one depending on your track plan.

The short frog rails beyond the unifrog get their power from link wires on the underside of the Peco turnout from the stock rails.

Just to be sure, by crossover you do mean 2 turnouts heal to heal, and not a diamond crossing don't you ?

[Jeremy Cumberland]

If you have an independently powered section of track, you need insulated joiners between it and any other independently powered section of track that might join on to it, otherwise the two sections of track won't be independently powered. This is a different issue from needing insulated rail joiners behind a live frog to guard against reverse polarity.

[IKB 1985]

Thanks all, it's a bog standard crossover consisting of two sets of points facing each other creating a sort of zig zag shape if you will. The issue I have is that these points need to be controlled from the outer circuit when accessing the yard, with the points set to curved, or as two independent loops with the blades set to straight. If I fit insulated rail joiners then option two works but not one, if I don't then the reverse is true. I'm just scratching my head how I can achieve both depending on the routing required. I'm increasingly being drawn to just going DCC and eliminating these quirks, at this stage of proceedings it would be relatively straightforward.

[Dominion]

If you have power feeds to both rails on both tracks the cross over should work with 2 insulated joiners. Is that what you have ?

[Jeremy Cumberland]

As I understand it, you have an outside loop, an inside loop, and a yard that is on the inside of these loops, something like this:

 

You want power to the yard to be from the inside loop when the crossover is set normal, and you want power to the yard to be from the outside loop when the crossover is set reversed.

 

With insufrog points you can just about get away with only having two track feeds, one to the outside loop and one to the inside loop (the inside loop feed must not be placed between the crossover and the yard points), but (or perhaps I should say BUT) you must then remember always to switch the points in the sequence yard points - inside crossover points - outside crossover points when sending a train to or from the yard from the outside loop (and the reverse sequence when resetting them) or else make sure that the inside loop track power is always turned off when setting the points from the outside loop to the yerd and accept that trains on the inside loop may get power from the outside loop controller while you are changing the points. This is the sort of thing I probably did on my very first layout, but it is so restrictive I can't possibly recommend it.

 

Instead, what you want is a third track feed, on the inside loop between the crossover and the yard points. You need to insulate this from the other two feeds by using  insulated rail joiners. There's no need to skimp on insulated rail joiners and so I recommend you use six (although you could get away with three if you are using a common return): One on each rail between the two crossover points, one on each rail at the frog end of the yard points and one on each rail at the frog end of the inside loop crossover points.

 

You now need a way of powering this third track feed from either the inside loop controller or the outside loop controller. In one way, this is straightforward enough: you need a DPDT switch (or an SPDT switch if you are using common return). If you are using point motors, then you can probably arrange for the switching to be done automatically (exactly how to do this depends on what point motors and point motor switches you are using). If you aren't using point motors, then use a separate switch, and remember to throw the switch at the same time that you change the points (the sequence of changing the points and throwing the switch does not matter).

 

Here is typical DPDT switch. Connect the middle pair of terminals to the track feed between the points, one of the outer pairs to the inside loop controller and the other outer pair to the outside loop controller, using one side of the switch for the inner rail and ther other side for the outer rail.

[IKB 1985]

Thank you very much Jeremy, I had to read it a few times but I do believe you have it cracked. This would also mean adding extra power feeds beyond the IRJs to ensure continuity but it would work. I need to give some serious thought to whether these sorts of workarounds are what I want to go with or just fit DCC and be done with it. It seems that the hobby seems to continue to edge in that direction but that's another discussion.

 

Thank you very much for taking the time to explain that, it expands my understanding a little further and it's much appreciated!

[DCB]

Unifrog are non isolating points,  Unlike Isolating points or Peco  Electrofrog   points they have no switch contacts to fail.   If the plan was DCC or one engine in steam DC it would work without any insulated joiners, just like Insulfrog.  For more than two locos on a DC layout I would sell the Unifrogs to someone using DCC and get some Insulfrogs and run trains instead of head scratching over wiring.     If you put a short straight between Jeremy's siding and crossover to take a power clip and use controllers with an off position you don't need any isolators with Insulfrogs, just 2 controllers and 2 power clips. And they have much smaller dead frogs

Unifrog needs an isolator for any siding where a loco is to be stabled, Insulators between crossover points plus a frog polarity switch  on each point  and a change over switch for the section between crossover and siding.  

2 hours ago, Jeremy Cumberland said:

 

With insufrog points  (the inside loop feed must not be placed between the crossover and the yard points),

 

That is wrong, for minimum wiring the feed should be between the crossover and Siding, that allows the inside train to remain stationary when the outside train accesses the siding

Unifrog makes a lot of sense for DCC or for using DC outside in the rain on a one engine in steam layout ( as I do) or using more than 1 amp DC ( asI have) but it's an enormous amount of hassle otherwise

[Jeremy Cumberland]

6 hours ago, DCB said:

That is wrong, for minimum wiring the feed should be between the crossover and Siding, that allows the inside train to remain stationary when the outside train accesses the siding

Yes, I suppose that would be better, using the inside loop controller to move trains between the outside loop and the siding. I was trying to work out how you would do it using the outside loop controller.

[IKB 1985]

DCB you're pretty much nailed my dilemma. As I use Code 55 N gauge finescale on my scenic section I have a choice of Unifrog or Electrofrog. There is no Insulfrog. I think this settles it that DCC is going to suit my needs far better in the longer term making for simpler wiring and more straightforward operation. 

 

Thank you all for your insights and experience, it's much appreciated!

[DouglasKerr]

We have all been struggling for years with experienced and very expert Electronic Engineers reduced to tears as they cannot get across the truth that irrespective of wither Traditional or DCC the same electrical laws/rules apply.
The Spin Doctors all convinced us that there would be less wiring, not really true, it has just been packaged up into expensive boxes, then further aggravated by the need for heavy gauge electrical wiring and need for droppers every 3 or so feet. This final point nullifies the usefulness of Unifrog, the vast majority of us are exacerbated by the lack of good quality insulated fishplates. Has anyone asked what is the Mean Time Between Failure of the decoders. It is zero potential difference that is required not always on which will drastically shorten functionality of decoders.

Whomever thought up Unifrog did not appreciate the consequences. The manufacturers have just used DCC as an excuse to increase turnover. Now in addition to the points you need a point motor a, minimum of two micro switches additional wiring and switches, making them a necessity not an option. The DCC users are going to lynch Peco when they find out.
Unifrog is not suitable for most home use. For the novice/young we need Insulfrog and the rest of us Electrofrog.

Perhaps we might be saved by Bachmann reworking the old Graham Farish Formoway points.