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LED Indicators for Turnouts.

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LED Indicators for Turnouts.
Posted by JDVass on Monday, December 19, 2011 6:15 PM

Well over the weekend I finished the bechwork and track for my Black River Juction layout. I am using the Kato Unitrack turnouts and would like to control them with DCC. On my old layout I used Atlas turnouts and MRC AD360 decoders. These decoders had LED's to indicate turnout position but they can't control the Kato bi-polar turnouts.

Does anyone know of another decoder that has the ability to both control bi-polar turnouts as well as indicate turnout position with LED's? Or how to have LED's indicate turnout position with a decoder that doesn't have this feature, such as the Digitrax DS64?

Life is too short not to play with trains, so grow old not up my friends.
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Posted by rrinker on Monday, December 19, 2011 9:51 PM

 The easiest thing might be a microswitch set to be triggered by the throwbar movement.

                      --Randy

 


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Posted by BroadwayLion on Monday, December 19, 2011 9:58 PM

Yeah. That's what you get with all of this new-fangled DCC stuff!

Give me an old GRS Tower, and it will work just perfectly!

 

THAT is how you run a railroad!

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Posted by rrinker on Monday, December 19, 2011 10:08 PM

 AH but Lion, the cool thing about DCC is that nifty panel could interface to the layout with ONE 6-wire phone cord. There's a good example of one, build from a REAL US&S machine, on the RR-CirKits web site. Same thing could be done with a GRS type machine, or even an NX (I'd LOVE to get a hold of an actual NX and wire it up to actually use it - since to be accurate that's what my prototype actually used on the portion of the line I intend to model). All the wiring is int he pnael, the switches and indicators to DCC interface boards, and they send signals to the devices out on the railroad over the DCC bus connected via the phone cord.

 I use servos to operate my turnouts, the controllers work on DC or DCC, include pushbuttons AND LEDs plus are DCC decoders (but again - don;t need DCC to operate - there are pushbuttons) all for less than the cost of just the Tortoise motor - let along switches, LEDs, and a DCC decoder.

                --Randy


Modeling the Reading Railroad in the 1950's

 

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Posted by Texas Zepher on Monday, December 19, 2011 11:14 PM

JDVass
Does anyone know of another decoder that has the ability to both control bi-polar turnouts as well as indicate turnout position with LED's? Or how to have LED's indicate turnout position with a decoder that doesn't have this feature, such as the Digitrax DS64?

By bi-polar do you mean that the turnout is controlled by changing the polarity of the power such as a stall motor turnout drive?  

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Posted by CSX Robert on Monday, December 19, 2011 11:21 PM

JDVass

...On my old layout I used Atlas turnouts and MRC AD360 decoders. These decoders had LED's to indicate turnout position but they can't control the Kato bi-polar turnouts...

Actually I believe the AD360 can control Kato turnouts.  If you wire it like the manual says to for slow-motion switch machines, but set the jumper for momentary instead of latching, it should work with Kato turnouts.

 

One option is to use another accessory decoder that can control LEDs and set it to the same addresses as the decoder you use to control the turnouts.

 

If you don't mind opening the bottom of the turnout to get access to the frog, here is a circuit I came up with that  will display the turnout position:

                        

One nice thing about this circuit is it will continue to show the correct indication even if the turnout is thrown by hand.

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Posted by rrinker on Monday, December 19, 2011 11:44 PM

Texas Zepher

 JDVass:
Does anyone know of another decoder that has the ability to both control bi-polar turnouts as well as indicate turnout position with LED's? Or how to have LED's indicate turnout position with a decoder that doesn't have this feature, such as the Digitrax DS64?
By bi-polar do you mean that the turnout is controlled by changing the polarity of the power such as a stall motor turnout drive?  

 Kato turnouts are oddballs. They have a single coil and a magnetic armature, A pulse of one DC polarity moves things one way, a pulse of the opposite DC polarity moves things the other. So they need a reversing DC power supply like a stall motor, but only in a pulse like  twin coil motor.

               --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by JDVass on Thursday, December 22, 2011 9:24 AM

CSX Robert

 JDVass:

...On my old layout I used Atlas turnouts and MRC AD360 decoders. These decoders had LED's to indicate turnout position but they can't control the Kato bi-polar turnouts...

Actually I believe the AD360 can control Kato turnouts.  If you wire it like the manual says to for slow-motion switch machines, but set the jumper for momentary instead of latching, it should work with Kato turnouts.

 

One option is to use another accessory decoder that can control LEDs and set it to the same addresses as the decoder you use to control the turnouts.

 

If you don't mind opening the bottom of the turnout to get access to the frog, here is a circuit I came up with that  will display the turnout position:

                        http://www.trainboard.com/railimages/data/500/kato_dcc.jpg

One nice thing about this circuit is it will continue to show the correct indication even if the turnout is thrown by hand.

That circuit looks like the way to go. Will it work with both the Kato HO #4 and #6? (Sorry if thats a silly question but they have different styles of frogs) I already gave my MRC decoders to a friend to use on his layout so I can't try hooking it up like you said to.

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Posted by Texas Zepher on Thursday, December 22, 2011 12:28 PM

rrinker

 Texas Zepher:

 JDVass:
Does anyone know of another decoder that has the ability to both control bi-polar turnouts as well as indicate turnout position with LED's? Or how to have LED's indicate turnout position with a decoder that doesn't have this feature, such as the Digitrax DS64?
By bi-polar do you mean that the turnout is controlled by changing the polarity of the power such as a stall motor turnout drive?  

 

 Kato turnouts are oddballs. They have a single coil and a magnetic armature, A pulse of one DC polarity moves things one way, a pulse of the opposite DC polarity moves things the other. So they need a reversing DC power supply like a stall motor, but only in a pulse like  twin coil motor.

 

Ah! Learn something new every day.  My club used a half wave AC system to accomplish a similar thing for screw-drive turnout motors.  They required a bit more time than a single pulse to throw them though so they were just momentary contacts that the operator had to hold down until the turnouts threw.

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Posted by CSX Robert on Thursday, December 22, 2011 2:54 PM

JDVass

...

That circuit looks like the way to go. Will it work with both the Kato HO #4 and #6? (Sorry if thats a silly question but they have different styles of frogs)...

Not a silly question at all.  I don't have any experience with the HO Kato turnouts(I'm an N scaler), but as long as they have a powered frog this circuit should work.

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Posted by JT505 on Wednesday, August 22, 2012 3:25 AM

I like the circuit and have wondered why it is not a standard approach for indicators.  What are the values (or part numbers) for the parts in your circuit.

Thanks in advance, JT

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Posted by Dr.Gonzo62 on Wednesday, August 22, 2012 3:21 PM

I've used 1N4001 diodes and 1 kOhm / 1/4 watt resistors. Higher or lower resistor values will give you dimmer or brighter LEDs. Try that for yourself.

Kyle

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Posted by NP01 on Thursday, August 23, 2012 12:15 AM

Don't know why the 1N4001 is needed. Perhaps a 600 ohm resistor would be enough, 1K will constrain the current by almost half of the requisite 20 mA. 

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Posted by rrinker on Thursday, August 23, 2012 6:33 AM

 LEDs can't take as much reverse voltage as an ordinary diode like a 1N4001 can, the 1N4001 is there to protect the LED from the excessive reverse voltage.

                  --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

PED
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Posted by PED on Wednesday, October 19, 2016 8:49 PM

CSX Robert

 

 
JDVass

...On my old layout I used Atlas turnouts and MRC AD360 decoders. These decoders had LED's to indicate turnout position but they can't control the Kato bi-polar turnouts...

 

Actually I believe the AD360 can control Kato turnouts.  If you wire it like the manual says to for slow-motion switch machines, but set the jumper for momentary instead of latching, it should work with Kato turnouts.

 

One option is to use another accessory decoder that can control LEDs and set it to the same addresses as the decoder you use to control the turnouts.

 

If you don't mind opening the bottom of the turnout to get access to the frog, here is a circuit I came up with that  will display the turnout position:

                        

One nice thing about this circuit is it will continue to show the correct indication even if the turnout is thrown by hand.

 

 

I know this is an old thread but I have a question about this diagram. I understand how a green and red LED works in this diagram but I would like to use a single bipolar red/green LED instead of two seperate LEDs to indicate turnout position. I would be using this on DCC with Kato turnouts as discussed earlier in this thread.

If I used a red/green bipolar LED (3 leg version) driven by the DCC track power without the diodes shown, the LED is orange in all cases. My question is - with the diodes installed, do they restrict the reverse current enough such that the LED will show as either red or green (not orange).

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

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Posted by rrinker on Thursday, October 20, 2016 6:55 AM

 The reason it's always orange is because internally, the LEDs both tie the same side to the common leg - so it would be as if you took this digaram and flipped one of the LEDs. Adding the plain diodes won't work. If they face the same way as the LEDs, then they do nothing except drop the voltage a little. If they oppose the LEDs, then neither LED will ever turn on. It won't work with bicolor LEDs.

                                --Randy

 


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Posted by CSX Robert on Thursday, October 20, 2016 8:30 AM

PED
If I used a red/green bipolar LED (3 leg version) driven by the DCC track power without the diodes shown, the LED is orange in all cases.

First, a quick correction: a bipolar Led generally does not have three legs - it has two LEDs wired in reverse parallel and generally only two legs.  A bipolar LED will not work in this circuit, but a three-legged, common cathode or common anode, bicolor LED will work.  How do you have yours wired?  You would need to have the common leg wired to the frog, one other leg wired to rail A through a resistor and the last leg wired to Rail B through a resistor.  It would work without the other diodes, but you really should have them for reverse polarity protection for the LEDs.

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Posted by CSX Robert on Thursday, October 20, 2016 8:38 AM

rrinker
...it would be as if you took this digaram and flipped one of the LEDs...

If you flip one of the LEDs in that diagram, it would still work (as long as you also flipped the corresponding reverse voltage protection diode).

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Posted by rrinker on Thursday, October 20, 2016 12:22 PM

 Yes, but the 3 leg bi-color LEDs are fixed in the package and are either common cathode or common anode. With individual LEDs you simply wire as shown and it works. They do not have to be the same color LEDs, but bi-color ones won't work here.

                                     --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by CSX Robert on Thursday, October 20, 2016 1:42 PM

rrinker
 Yes, but the 3 leg bi-color LEDs are fixed in the package and are either common cathode or common anode...

 

Doesn't matter.  I show the LEDs wired anode to cathode, but they don't have to be, they can be anode to anode or cathode to cathode as well.  Each leg of the circuit is independent of the other.  It will work just fine with a three legged LED as long as it is wired correctly.

PED
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Posted by PED on Thursday, October 20, 2016 4:13 PM

CSX Robert

 

 
PED
If I used a red/green bipolar LED (3 leg version) driven by the DCC track power without the diodes shown, the LED is orange in all cases.

 

First, a quick correction: a bipolar Led generally does not have three legs - it has two LEDs wired in reverse parallel and generally only two legs.  A bipolar LED will not work in this circuit, but a three-legged, common cathode or common anode, bicolor LED will work.  How do you have yours wired?  You would need to have the common leg wired to the frog, one other leg wired to rail A through a resistor and the last leg wired to Rail B through a resistor.  It would work without the other diodes, but you really should have them for reverse polarity protection for the LEDs.

 

I do not have any wired at this point. I know how to wire up two seperate LED's but my goal is to use a single three leg bicolor LED (DCC track powered as you noted with common to frog and other two legs to rail A and B) as a turnout indicator with red or green showing (not orange) according to turnout position. I wanted to make sure the LED color would reflect a red or green and not a orange. Although you do not specifically state that, I think that is what you are implying since only one side of the LED is active in your diagram.

I have used three leg bicolor before but they were always DC driven switched by a Tortoise. I did not know how they would react to the A/C track power in a DCC situation.

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

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Posted by rrinker on Thursday, October 20, 2016 4:34 PM

 Wait, it must be hooked up wrong. If it's a 3 lead LED, the common needs to go to the frog. If it lights up orange, these must be different turnouts with an always live frog, not power routing. On some Kato turnouts this is switchable, if this feature is turned off none of these circuits will work as expected.

Rail A---<resistor>----->|-----<frog>-----|<-----<resistor>---Rail B

There's no way that can light up orange. Only possible way is if the two LED wires are both connected to the same rail, or connected together to the frog, and the common wire in the LED is connected to the other rail.

                                --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by PED on Thursday, October 20, 2016 4:50 PM
I am only using Kato #6 (no #4) and they are power routing thus the frog changes back and forth from Rail A or B according to direction turnout is thrown. Wiring common leg of three leg bicolor LED to frog and other two legs to rail A and B respectively should cauls LED to change color according to direction turnout is thrown. My main question was how the bicolor LED would react to being powered by the A/C power on a DCC track. I know how it works with DC but was not sure how (or if) the A/C changes the picture. I searched web and was not able to find a clear answer. Most discussion involves DC, manual DPDT, Tortoise machines, etc but never found a clear discussion on driving a single three leg bicolor LED directly from DCC track power.

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

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Posted by rrinker on Thursday, October 20, 2016 6:02 PM

 It shortens the life of the LED, but by how much is always the question. It doesn;t seem to be much, at least if you are using a decent amount of resistance and keeping the reverse current low. Maybe they last 8 years instead of 10 or something.

 The only way to block it with a 3 lead LED is to install a pair of regular diodes antiparallel to each of the internal LEDs. If the LED is say common cathode, hook the anodes of two regular diodes to the common lead and the cathode of each to one of the legs. This way the reverse current will flow in a forward direction through the regular diode, and the LED will only see about .7V reverse voltage and be perfectly safe.

                            --Randy

 


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Posted by CSX Robert on Thursday, October 20, 2016 6:14 PM

PED
If I used a red/green bipolar LED (3 leg version) driven by the DCC track power without the diodes shown, the LED is orange in all cases...

This statement confused us because it sounded like you had actually tried it and got orange.  I think you are confusing 3-lead and 2-lead bicolor LEDs.  With a 2-lead  (bipolar) LED, the polarity controls the color: one polarity DC=red, other polarity DC=green, AC (reversing polarity)=orange.  With a 3-lead LED the color is dependent on the path through the LED: common to one other lead=green, common to third lead=red, common to both other leads=orange.  With the 3-lead LED, reversing polarity does not change the color - one polarity lights it and the other does not, and AC will light it half of the time.

 

PED
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Posted by PED on Thursday, October 20, 2016 8:58 PM

I have the concept now but am not sure of some of the details about location and orientation of some components. 

1)Assuming I tie common to frog and the other two leads to the rails, should I look for common cathod or common anode? Web info suggest common cathode is most common.

2) I am not an electronics person but my reading of your diagram tells me you wired in following sequence (common cathode style?) Frog > resistor > anode (LED) cathode > anode (Diode) cathode > Rail A or B. Is that correct? I assume this provides the current limiting in the reverse direction.

3) If 2 above is correct, would a single resistor in the frog leg work OK rather than using two resisters as you show?

4) If 3 above works, can I flip the LED and diode direction to rail B so that it looks like rail A?

5) If 4 above works, can I move diode to frog leg?

To me the new circuit would be FROG > resister > anode (Diode) cathode > (split into two legs for rail A and B) to anode (rail A LED) cathode > rail A and similar for rail B LED leg

Sorry if this sounds confusing but I have over 40 turnouts and I am trying to make circuit as simple as possible to make it easier. I have already opened up a turnout and see several ways to tap into the frog. I am reluctant to modify all my turnouts and introduce a potential failure spot but will do it if necessary. I know how to do it by taping into track but that introduces a different set of problems.

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

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Posted by hon30critter on Thursday, October 20, 2016 10:37 PM

PED:

Have you seen this information on Kato turnouts:

http://www.wiringfordcc.com/switches_kato.htm

It doesn't address your specific question about hooking up turnout indicators so I'm not sure if there is anything helpful in there, but it might be worth a read if you haven't already.

Dave

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Posted by rrinker on Friday, October 21, 2016 7:19 AM

Common cathode or common anode does not matter since DCC is AC. Common goes to the frog, regardless of which is it. The resistors should go into the other two legs, it's best to have one resistor for each LED in the package rather than a single resistor on the common.

 Usually but not always the middle of the 3 wires is the common. I'm not exactly sure what you are asking but keep it simple, All you need is the 3 lead bi-color LED and 2 resistors. Again, common anode or common cathode does not matter, it will work with either type. Rail A to resistor to one side of the LED. Rail B to a resistor to the other side of the LED. Middle of the LED to the frog. Done. If it lights up red when you want green and vice-versa, reverse the Rail A and Rail B wires. Unless you are buying some strange LEDs, a 1K resistor should work fine.

                               --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

PED
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Posted by PED on Friday, October 21, 2016 7:52 AM

Thanks Randy. Exactly what I needed to know.

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

PED
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Posted by PED on Friday, October 21, 2016 8:00 AM

hon30critter

PED:

Have you seen this information on Kato turnouts:

http://www.wiringfordcc.com/switches_kato.htm

It doesn't address your specific question about hooking up turnout indicators so I'm not sure if there is anything helpful in there, but it might be worth a read if you haven't already.

Dave

 

Yes, I have seen that. However, his info is misleading about how Kato n scale #6 power route. The frog is power routed as well as the rail in the chosen route. However, the frog rail in the route not chosen is dead. That means that only one frog rail is powered at a time and the other is dead. His diagram would imply that both frog rails are always powered.  However, if you do want both frog rails powered all the time, you can put some jumpers inside the turnout to do that OR you can make sure you add power in the track for the frog rails somewhere after the turnout.

Paul D

N scale Washita and Santa Fe Railroad
Southern Oklahoma circa late 70's

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