Limit switches for frog switching.

[Aussie 3 railer]

Hello All,

Hoping for some help here, somewhere, here I think maybe in one of Brian's tutorials about using 2 limit switches for reversing frog polarity. I have a bit of time on my hands waiting for a knee replacement so thought I might keep myself busy and fit up servos to some of my points.

I actually need a wiring diagram if possible. Nothing on Google is very clear exactly how to do it.

Thanks in advance for any assistance.

Dirk

[Tricky Dicky]

You only need one changeover switch usually a micro switch which has NO (normally open) NC (normally closed) and COM (common) terminals. Wire the COM to the frog wire and the other two terminals to the stock rails. If it does not work right then swap the the two stock rail connections. I seem to recall you are using unifrog points so I think that is all you have to do for standard electro frog points there is a little more work involved.

Richard

[Brian]

A liitle caution is needed on a DCC layout when using one micro switch to flip frog polarity, as its possible to have the micro switch change over polarity as soon as the point / servo arm starts to move and the actual point blade to stock rail are still closed together! A short then occurs as the micro switch has flipped over the frog polarity and the switch rail and the frog are still at the original polarity! On a DCC layout its almost certain the DCC system will trip out, DC (Analogue) layouts may 'see' the short but usually their overload trip won't be fast enough to cut off power and the short is removed as soon as the point blade opens. Here IMO its best to use two micro switches - one on each side of the servo with their common tabs connected together and then feeding the frog and the NO (normally open tab used to take the feed from the rails or DCC Bus pair. Normally left rail to left micro and right rail to right micro.
However, this is not the case where each point blade is bonded to the adjacent stock rail and the two closure rails are isolated from the frog rails via a gap in each of the closure rails. Or by using Unifrog points which have factory fitted bonded switch rails to closure rails and the frog is pre isolated. Then one micro switch will be fine for frog polarity. A second micro can then be used for other operations such as panel LED point position lights or signal aspect controls.

[Aussie 3 railer]

Great work with the replies many thanks. I remember seeing similar but couldn't remember or find them.

Just on another query with Unifrog points is it worthwhile adding droppers similar to the Electrofrog conversion. All I can see with Unifrog is they only get their power supply from fishplates.

Newer Unifrog don't have the frog wires but there is now a bigger area to mske soldering a wire a hell of a lot easier.

Dirk

[Brian]

Great work with the replies many thanks. I remember seeing similar but couldn't remember or find them.

Just on another query with Unifrog points is it worthwhile adding droppers similar to the Electrofrog conversion. All I can see with Unifrog is they only get their power supply from fishplates.

If your wishing to have absolutely the best power and data transfer to the locos then every piece of track including points has a pair of droppers fitted. Metal rail joiners are the weak link in the power and data transfer and IMO should only be used to align two abutting rails together.

Newer Unifrog don't have the frog wires but there is now a bigger area to mske soldering a wire a hell of a lot easier.

Dirk

Is that correct? I cant see how a Unifrog point can work if..... A) its isolated frog area has become larger, and B) If the Unifrog isn't prewired with a single dropper frog feed wire?
So are you sure what you have is actually a brand new Unifrog point??

From the Peco web site for OO/HO Unifrog points.... On a Unifrog turnout the frog tip and wing rails are electrically isolated from all other rails. The turnout can be used as supplied on a DC or DCC layout without any modification, using the standard SL-10 rail joiner. If desired, the frog tip and wing rails can be powered by connecting the wire welded underneath to a changeover switch or microswitch working in unison with one of our turnout motors. Basically, as supplied the turnout operates as an Insulfrog turnout. If the frog is powered then it operates as an Electrofrog turnout. So, the best of both worlds in one unit!

[Tricky Dicky]

Newer Unifrog don't have the frog wires but there is now a bigger area to mske soldering a wire a hell of a lot easier.

Dirk

They do have a wire welded on just like electro frog points. I have known wires come adrift but mainly on second hand points. Are you sure you have new unifrog points? A close up photo of the top and bottom view would clear that up.

Richard

[Aussie 3 railer]

I think I might be wrong here as I can't find the article I was refering to. What got me thinking at the time was I got this Electro frog that was missing the frog wire. I couldn't see any evidence thst it ever had one or that it had broken off. You can see in the attachment where I soldered my own from wire to the V rail mainly because my fine soldering abilities aren't there yet and to solder the underside was a risk. I actually used a piece of wire they use for typing up electrical cables so its a tad thicker than Peco wire. I can't show you the undersides as the point is glued down. I just received some new Uni frog points and they all have the usual frog wires where they should be.

Dirk

[Aussie 3 railer]

Not the best photo its in a bugger of a spot to get at.

[Brian]

The image above is of an early and standard Electrofrog point. It is not a Unifrog point.
Unless the under point closure rails to Vee rail bonding has been removed, (which I suspect has occurred hence the lack of the factory fitted frog wire) if the factory fitted wires are still in place, it will cause a short circuit as the outer stock rails have been bonded to their adjacent switch rails. Usually two gaps are made in the closure rails preventing the short occurring. See image below.
This point is of an earlier design from Peco, as more latterly nearly all Peco electrofrog points have two gaps factory installed and are supplied out of the box with these two gaps bonded across underneath. When the conversion to linking permanently the stock rail to switch rail is made the two little links are removed.

This is the SL-E96 from Peco and I have circled in red the factory installed gaps in the two closure rails.

[Aussie 3 railer]

Guess the best thing to do is rip it out and scrap it. Or can I test it in place as is and cut the gaps as needed. Can the factory wiring be removed from the top. What about the joiner wires I fitted and use as droppers should I remove them as well.

I have a new spare Uni frog SL-U8362 so maybe that's the better safer option and sort this point out later and use it elsewhere or bin it..

When I bought this point I had doubts about it as the package seal was broken open and I wasn't happy with the hobby shop. I now buy them and everything else from the one place. Back then stock was scarce and you had to buy from several shops its way better now thankfully.

Dirk.