Electrofrog points and DCC

[debe45]

After a couple of years with my first layout and experiencing several problems with points (insulfrog)  I wonder if on my new layout I should use electrofrog points. But this raises some points

1. Will I need the circuitry to change frog polarity or whatever it does, like in DC. Or can they just be used straight form the box ( so to speak)

2. Will I still need to use IRJ's.

I have read some of the threads on electrofrog but can't quite get my answers.

Thanks in advance for any advice or comments.

[morairamike]

Yes you have to use IRJ's. even though you are using DCC the rails can still be considered + & -. So when you look at a set of ponts with them set for straight through  (for this explanation the left rail is + and the right -). The frog in this case must be -. When the points change the frog becomes +. So you need IRJ's on the frog rails.  you also need some form of switch to change the polarity when the points change. If you use SEEP point motors with switching contacts, the change of polarity will be taken care of. Look up SEEP point motors on the web. 

[Chrissaf]

I use PECO electrofrogs.

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Although separately controlled frog switching is desirable. It is not a mandatory requirement. You can use the PECO electrofrog points straight out of the box 'as is'.

Out of the box, the frog polarity is controlled by the moving switch rails. You do however need to fit the IRJs (PECO SL11) on the two frog rails, else you WILL get a short circuit. You do not use DCC point clips with PECO electrofrog points. The inclusion of the necessary & required Insulated Rail Joiners may require you to install additional track power feeds to extend DCC power to track sections that then become isolated due to the IRJs.

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If you decide to go the whole hog and install frog switching, then on the underside of the point you will find two wire straps (marked A on the graphic below) between the frog rails and the switch rails. These will need removing so that the frog area is totally isolated at both ends, allowing the frog power to be controlled by the frog polarity switch. If you remove these straps, then I highly recommend that you add the additional straps between the switch and fixed rails (marked B on the graphic below). This improves electrical reliability as power on the point is not dependant upon the side contact sprung pressure between the moving switch rail and fixed rail. Fitting the 'B' straps will require soldering.

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Also, the combination of the A & B strap modifications together, virtually eliminate the possibility of wheel B2B issues causing a 'short circuit' as the rolling stock traverses the point. Which is the main reason that I recommend these modifications and frog power switching so highly.

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Note: For the eagle eyed amongst the forum readers. My text in the first paragraph states PECO IRJs are part number SL11. The PECO point graphic shows part number SL111. The PECO point graphic is taken from a Code 75 Finescale track product instruction sheet. Use SL11 IRJs for PECO Code 100 track and SL111 for PECO Code 75 track.

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There are two types of frog power switching. Mechanical, where the switch is part of (or attached to) the point motor. The details of which will be dependant upon the exact point motor used. And electronic where the frog power is provided by a frog power switching device that detects 'short circuit' currents and switches the frog DCC phase (polarity) to remove the short. This is very similar to the way an RLM works. The fully electronic six frog switcher documented on the linked 'point animation' page below is made by TamValley.

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Gaugemaster do a simple relay based DCC 80 frog switcher, but I have no experience of it and cannot say if it is any good or not.

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Note: The TamValley switcher works out at about £10 per frog, whereas the very basic DCC 80 unit above is £7 per frog. I have used TamValley products (but not this six port one) and think the additional £3 per frog is well worth the small additional cost.

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This web site (click link below) has got a very useful point animation that demonstrates the frog switching methods described above. The first animation on the page shows how the moving switch rails are used to control frog power (it is documented on the website as a DC wiring option, but can just as easily be DCC). This first animation is, in essence, the PECO electrofrog 'out of the box' wiring option. The second animation shows how a point motor switch (or electronic frog power switch) is used to control frog power using the PECO provided frog wire and wire strap modification option. The 'B' straps are not shown on this second point animation, but they are present because the moving switch rails maintain their respective polarities in both switched positions.

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http://www.009.cd2.com/turnouts.htm

TIP: On the linked page above, click the toggle switch icons next to the point graphics to operate the animation.

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Note: One other thing to be aware of. PECO SL electrofrog points use completely different geometry to Hornby. PECO's SL electrofrog points create track spacing of a nominal 50mm and not 67mm as used by Hornby. They are also longer points than Hornby as well. To generate the Hornby 67mm track spacing, additional 79mm lengths of straight track need to be inserted where points face each other (such as a cross-over between ovals for example). If you are using Code 100 electrofrog points, then you can use a PECO ST202 track piece. If you are using Code 75 electrofrog points, then these short straights will need to be cut from flexi-track. Either way, the increased space that a PECO SL electrofrog track layout will occupy will be significantly noticeable compared to a Hornby layout or a PECO Insulfrog layout using PECO ST set-track. PECO ST set-track shares the same geometry as Hornby, but PECO ST track is not currently available in an electrofrog version.

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For more information on PECO track part numbers and what they mean see this previous reply of mine:

https://www.hornby.com/uk-en/forum/another-b2b-question/?p=1/#post-202055

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[Rog RJ]

Electrofrog points will work straight from the box, as long as you use Insulated Rail Joiners  (IRJs).  However, to avoid the risk of momentary short circuits as trains pass through them and for long term reliability,  it is advisable to use frog polarity switching of some sort.

[debe45]

Thanks all.

A  complete technical answer from Chris. I  have yet to fully absorb it all but look forward ton that.

I use Wire In Tube for my point switching so can't use a frog switching.circuit Or can I?.  But your answers indicate I can manage without.

Thanks again

[Chrissaf]

I use Wire In Tube for my point switching so can't use a frog switching.circuit Or can I?

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You certainly can.

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If you use a very large slide changeover switch. The type that has a square plastic operating handle that projects from it. The wire goes through a hole drilled in the plastic square. The electrical part of the switch is a changeover contact. Wired such that sliding the switch, not only operates the changeover switch to power switch the frog, but also mechanically throws the point because the wire in tube is also attached to it.

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The slide switch idea is not mine. I came across it in this YouTube. Fast forward to 7 minutes into the video.

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You can also still use the electronic frog power switching i.e the Tam Valley and/or DCC 80 product from Gaugemaster. Both of these frog switching methods work independently from whatever method is used to physically switch the point over.

[debe45]

Thanks Chris.  A full and complete answer as usual

 

[john_doman]

I avoided electrofrog points for years, intimidated by the modifications/wrinig apparently required. I recently decided to give it a go, on the basis that they can be used straight out of te packet, with only the required IRJ. I have had no issues, and now regret not using them everywhere. I am now gradually replacing my insulfrog points, albeit with some surgery needed to adapt the track geometry. My best friend is my Xuron track cutter.

[Nick_]

I have used both the TamValley frog juicer and the Gaugemaster DCC 80 frog switcher and can confim both work perfectly so long as your DCC controller can supply at least 2.5A (for example elite or eLink with the 4A power supply). They are both easy to wire up.