Is it really easy to add indicator lights to Kato turnouts? Or am I crazy?

[quinntopia]

So I just discovered something kind of cool that you can do with Kato Unitrack and their 'electrified frogs'.  Essentially you can run a common wire from the frog and two wires from each of the outside rails and you have a perfect 3 wire connections for 2 color LED for Turnout indication purposes.  Maybe I'm too illeterate, but I've never seen this explained (except I have read posts on other forums of how it works with Peco frogs, which for a long time I thought was specific to just that design).

Of course, this method only works if your using DCC and have turnouts with powered/polarized frogs.

My concern is, well, I wrote this blog post about, and I'm not sure its correct as I'm really not good at electrical stuff.  It seems like it should be fine, but I don't want to give out terrible ideas on my blog!
What am I missing? This just seems too easy!

[CaptOblivious]

Saw the entry, it really is that easy. Doing it with DC is only one small step more difficult, too. Indeed, Tomix sells devices that you just can place between the rails that does something very similar to what your setup does.

[inobu]

Seems to me it would work with DC power routing but not sure how it would work on DCC.

I thought these turnouts #4 created problems with shorts depending on the wheel or something.


Inobu

[nik_n_dad]

We're planning on using the NCE "switch kats" on our new layout for DCC control of the turnouts, and they kindly have provided 3 solder points to add signals.  I've been trying to decide if I was going to build a central control panel or have signals on th layout.  I like what you are doing so may put the signals on the layout.

[quinntopia]

We're planning on using the NCE "switch kats" on our new layout for DCC control of the turnouts, and they kindly have provided 3 solder points to add signals.  I've been trying to decide if I was going to build a central control panel or have signals on th layout.  I like what you are doing so may put the signals on the layout.

Thanks Nik_n_dad! I will probably have turnout indicators on the layout where it might make some logic 'in the real world' to have them and where they would be helpful to determine which way the turnout is facing, and then have similar LED"s on the control panel.  I've been trying to figure out easy, convenient, or quick ways to do this with Unitrack (and my Minitrix switches) for some time (I actually didn't pay too much attention to the Switch Kats as I wasn't sure they would work for me, in retrospect, it seems they would!).  I basically have built a bunch of circuits that will allow two or three LED's indicators for the Unitrack switches (which are mainline switches for the most part), and will use small little red/green indicators for some of the yard leads.  For the engine terminal, I'm just going to have LED's on the control panel.  Man, there is so much work to do.....

Saw the entry, it really is that easy. Doing it with DC is only one small step more difficult, too. Indeed, Tomix sells devices that you just can place between the rails that does something very similar to what your setup does.

Thanks Capt!    I seriously woke up this morning wondering if I had done something terrible!  Now that this seems like an acceptable method (as far as the laws of electricity are concerned) I can start installing a few more other than the tests versions.

[westfalen]

Seems to me it would work with DC power routing but not sure how it would work on DCC.

I thought these turnouts #4 created problems with shorts depending on the wheel or something.


Inobu

We're running DCC with No.4's with no problems.

[KenS]

I thought these turnouts #4 created problems with shorts depending on the wheel or something.

Kato's #4 has the two point rails at opposite polarity (only the frog changes polarity), while the #6 has both point rails at the same polarity as the frog (all three switch).  This means that an out-of-gauge or oversize wheelset could short both rails near the frog on the #4.

The #6 doesn't completely eliminate the risk of a short, as it has a point rail of opposite polarity "near" the live rail at the tip (distant from the frog), but the spacing there is larger so a short is much less likely.

Thus, a Kato #4 will work with DCC, but you do run a greater risk of problems from out-of-spec wheels.

Seems to me it would work with DC power routing but not sure how it would work on DCC.

BTW, I too saw the posting about this on Quinntopia, and it's an interesting approach.  I'd never though of it before, but it makes sense.  The frog is always either the same polarity as the rail (no voltage differential, and hence a dark LED) or the opposite (lighting a LED in the proper orientation).  The difference between DC and DCC is that with DCC the orientation doesn't matter (if the polarity differs there's always a current flowing in each direction half the time).  The problem with DC is that polarity also matters (since LEDs only work in one direction), and since track polarity can be reversed, an arrangement that works for trains running one direction won't work for trains running the other.  That shouldn't be a problem if you're using signals that face a particular direction (rather than a panel indicator where one light is expected to work for both), it just means you need to pay attention to that detail for DC, where you can ignore it for DCC.

Note that you're burning 20 mA for each LED, which can add up if you have a lot of these on the track.  Since they're track powered, that comes out of your supply for running trains.  Still, you'd need 50 lit LEDs to lose even an Amp, so you'd need a fair number of switches to have a problem.

Here's a quick graphic I drew (modified from one of my Kato #6 diagrams).

[inobu]

It appears to me that the principles are based on power routing of the turnouts using the frog leads to act as a power switch. Which I got. Where I am confused it the power itself. The power supplied to the rails with DCC most likely appears every where on the track (on all three legs of the #4) unless you are power switching.

The problem I see is that power switching a turn out de-energizes one leg of the route which limits track operations in that area or segment of the layout which goes against the basis of DCC (we want operations everywhere).

Some one help me out. what am I missing or is it an excepted trade off?


Inobu
   

[KenS]

I'm not quit sure what you're asking. Power-routing turnouts (like the Kato #6 I illustrated) work fine with DCC.  You just have to insulate the rails leading from the frog (on the right in my diagram) and add a feeder beyond it. (actually, you could probably omit the insulator with the #6, since it never changes phase on the output rail, but you'd run a greater risk of a short at the frong; I'd insulate). 

Actually using the power-routing feature of the turnout to de-power a siding does run counter to the usual DCC idea of having every track live, but I could see doing that in a yard to de-power parked trains (a stored train isn't likely to have its lights on, although with sound it might have the motor idling).

But that really doesn't have to do anything with what Quinntopia is proposing, which is simply using a LED to sense the polarity (or "phase" for DCC) of the frog relative to one of the rails as a means to sense which way a turnout with a powered frog is thrown. Unless I misunderstood him.

[inobu]

Ohh, ok

The way I read it was to connect the 2 rail wire and one common lead (frog) to run the 2 color LED. Did not realize that it was going to be a sensing tap. That mean a basic comparator circuit right? 

Now, I got it.

INobu

[CaptOblivious]

There's no "sensing" going on. Ken, your diagram makes it clear: When the track is diverging, the frog and the non-diverging rail are at the same voltage, DC or DCC, and so no current can pass through the LED. But the diverging rail and the frog are at opposite voltage, DC or DCC, and so current can pass through the LED (if it is oriented the right way on DC; regardless on DCC).

[KenS]

That's what I meant by "sensing" (voltage difference).  I wasn't suggesting a more complex circuit.

[inobu]

I guess I need to sit this one out and watch and learn.

Inobu

[quinntopia]

I don't really understand a lot of this, but what I hoped (and you kind folks have confirmed) is that since the frog changes polarity with the direction of the switch, you have a really easy way to use the 3-lead led's to switch from red to green.  For a lot of modellers, adding simple indicators is something they want, but quickly get overwhelmed with electrical terms and solutions that can be a bit overwhelming.  Calculating resistance for LEDs' given various power supplies is about my limit for electrical knowledge, although I am working expanding this knowledge, its mostly to try and interpret and then build some of the helfpul, but still not intuitive (to me!) circuit diagrams, etc....

Anyway, bottom line is I am amazed at how easy this solution was for me (and hopefully others).  Granted, this type of signal indication is not prototypical at all, but it helps to make things a bit easier to manage with turnouts etc...

Note that you're burning 20 mA for each LED, which can add up if you have a lot of these on the track.  Since they're track powered, that comes out of your supply for running trains.  Still, you'd need 50 lit LEDs to lose even an Amp, so you'd need a fair number of switches to have a problem.

This is a concern!  I plan on doing this to probable about 10 or 12 turnouts max, so I think I'll be okay.  I haven't done the math on the actual draw, but I figure the power draw will be somewhere around the same draw that a fully lit passenger train draws.  I've had a couple of these on the track while other trains were running and never experienced too many problems, but to ensure that I'm not drawing away too much power,  I'm also configuring all my yard tracks so that I can power off these same 'power-sucking' but static passenger trains in sidings to ensure that plenty of power is left for the running trains and, of course, these led signals.

[inobu]

I guess I just missed everything. I was looking at connecting at the legs of the turnout not on the option points.   

So, I pulled out a number #4 wired it up and started laughing. No brainer. In your face easy. Now I know what you meant by Am I crazy.
The funny thing was the Japanese logic with the screw option. positive acknowledgment. You open (remove screw) on the option you want.

Came back to post my finding and saw Ken diagram (more insult to injury) Don't know how I missed it all.

Inobu
   

[nik_n_dad]

Quinn-

On your blog, I was curious- why did you choose the ground level \ NJ signals in some places and the tower \ Berko signals in other areas?  You've convinced me to put the signals on the layout, and I was trying to understand your thoughts.  Thx....

[quinntopia]

On your blog, I was curious- why did you choose the ground level \ NJ signals in some places and the tower \ Berko signals in other areas?  You've convinced me to put the signals on the layout, and I was trying to understand your thoughts.  Thx....

The NJ signals will be for the yard lead(s) - which would make more sense at ground level as you'd expect the engineer to be shunting or making moves at low speeds and a large signal on a mast isn't necessary (logical in my little world!), while the Berko signals will be for main line indication (and some other signals on 'traditional' masts etc...).

[biggulz]

Does anyone know if the Tomix 0112 Destination Signal will work with the Kato Unitrack switches on DCC. This seems like an easy solution to have between the rails.

[scott]

For a lot of modellers, adding simple indicators is something they want, but quickly get overwhelmed with electrical terms and solutions that can be a bit overwhelming.

Yeah--I hit that point just a few posts into this thread.       

But it sounds like a very cool idea.

[scott]

Does anyone know if the Tomix 0112 Destination Signal will work with the Kato Unitrack switches on DCC.

...or with DC?

[KenS]

Does anyone know if the Tomix 0112 Destination Signal will work with the Kato Unitrack switches on DCC. This seems like an easy solution to have between the rails.

It seems unlikely to work with DCC.  Since it's for Tomix, which doesn't sell DCC, it's most likely just a pair of LEDs, one in each direction (with appropriate resistors).  On DCC, since both polarities are always present, both LEDs should light (half the time, but you'd never see that except perhaps as a loss of intensity).

Whether it works with Unitrack or not really just depends if the geometry will hold it in place between the rails.  That seems likely, but you can't really know unless someone's tried it.

Edit: fixed typo.