Model railroad turnout indicators

Thread Starter

jfedorek

Joined May 3, 2020
7
am also trying to do a similar idea that I can not figure out. I would like to install indicator light on my kato turnouts. I would like the green light on the track that’s open and a red light on the one that is not. They are a signal coil that only uses momentary power to move the turnout. Reversing polarity moves it back. Can this be done some how ? They are twined together so I am using 18 volts dc with a dual button board.
CA1F25EB-154E-4513-A093-F2B55E5A241C.jpegStuck here because I can’t figure out how to get lights to stay on with momentary power only
 

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KeithWalker

Joined Jul 10, 2017
1,917
The simplest way would be to attach a microswitch to the underside of the turnout which activates when the rail moves. They usually have a normally open and a normally closed contact which can be used to connect power to the two indicators.
Regards,
Keith
 

Alec_t

Joined Sep 17, 2013
12,201
Agreed. I think that would also be the safest way. The position of the turnout is key, because if friction or some other cause prevented the changeover of the turnout, a wrong indication could be given by a circuit which merely responded to the coil pulses.
 
Is the frog powered? If so, it probably changes polarity depending on the turnout's position - can check with your multimeter. (Remember: for a left-diverging turnout, when the switch is set to main, the frog will be the "left" rail, but when switched, it becomes the "right" rail, so that the engine continues to get the correct polarity.) So use LEDs, which like any diode, are directional, to only turn on when the polarity is in the correct direction.
Solder wires to the outside tracks (like a feeder wire) and to the frog (and check that they don't interfere with any wheels or flanges - file them down as needed.) Then add two LEDs, both connected to the frog, then one going to each rail, so each one only turns on when the polarity is in the correct direction. Be sure to add the correct resistor to each LED to limit the power from your track to match the LED's needs.
A more-detailed example may be found here: https://www.trainboard.com/highball/index.php?threads/kato-switches-and-digitrax-ds-64s.94625/
 

Thread Starter

jfedorek

Joined May 3, 2020
7
The frog is insulated. There are actually 4 terminals inside the turnout. I soldered words to them and can get the lights to come one accordingly. The only issue is in dcc the les lights seem to make all the rails common some how and short out the locomotives
 

Thread Starter

jfedorek

Joined May 3, 2020
7
The simplest way would be to attach a microswitch to the underside of the turnout which activates when the rail moves. They usually have a normally open and a normally closed contact which can be used to connect power to the two indicators.
Regards,
Keith
Simple is good. I no nothing about those. Would you be able to post a pic or a link for me of the micro switch you recomend
 

Alec_t

Joined Sep 17, 2013
12,201
Try a lever microswitch, such as one of these. If I'm reading the datasheet correctly, the D2FD-L1-1T needs only ~5gm (or is it 66gm?) and 3mm of movement to operate it.

Microswitch.png
If that's too much force, then perhaps you could use a SPDT reed relay and a small magnet attached to the frog.
 
Last edited:

Thread Starter

jfedorek

Joined May 3, 2020
7
Is the frog powered? If so, it probably changes polarity depending on the turnout's position - can check with your multimeter. (Remember: for a left-diverging turnout, when the switch is set to main, the frog will be the "left" rail, but when switched, it becomes the "right" rail, so that the engine continues to get the correct polarity.) So use LEDs, which like any diode, are directional, to only turn on when the polarity is in the correct direction.
Solder wires to the outside tracks (like a feeder wire) and to the frog (and check that they don't interfere with any wheels or flanges - file them down as needed.) Then add two LEDs, both connected to the frog, then one going to each rail, so each one only turns on when the polarity is in the correct direction. Be sure to add the correct resistor to each LED to limit the power from your track to match the LED's needs.
A more-detailed example may be found here: https://www.trainboard.com/highball/index.php?threads/kato-switches-and-digitrax-ds-64s.94625/
Sorry I misinformed you earlier the frog is hot like you said there ate axial my 4 terminals in the turnoutfir all the rails I can get the led bulbs to function the way I want but it seems to make all the rails common when the bulbs illuminate and short our locomotive in dcc I am just using plain white led bulbs with no resistors for testing purposes how can I stop the circuit from closing to the track when the bulb turns on? Forgive my poor understanding as I am new to this and have a project stuck on my head
 

Thread Starter

jfedorek

Joined May 3, 2020
7
Interesting everyone is saying micorosa itch. I am only scared to try this because of lack of knowledge and experience. These turnouts are worth 90$ . I am unable to find a video of someone doing this so I can completley understand how to do this I have a turnout that is in rough shape that I can test on and would love to learn but don't even know where to start. Died each turnout need 2 micro switches? The frog only moves on the top side
 
No, only a single SPDT switch is required, BUT if you want an intermediate position (not fully in either position), then two switches would be required. The intermediate position would be both lights off.
 

Thread Starter

jfedorek

Joined May 3, 2020
7
Thank you everyone for all the info. Just one more question. I am not sure how to Ttach switches or magnets with out affecting the trains . With leads on terminals and a powered frog, can't one use the frog to route the power to the indicator light since it routs power to the direction it's throwen with out any switches or relays?
 

KeithWalker

Joined Jul 10, 2017
1,917
How you attach the switch and what you use will depend on the gauge your trains and the type of actuator you are using. Can you post pictures with information?
Regards,
Keith
 
These https://www.electronics-tutorials.ws/diode/diode_7.html?utm_referrer=https://www.google.com/ would be the extra parts for each coil if you did it without a limit switch.

The magnetic latching relay holds it's state when power goes away. One latching relay per turnabout.

What you do is pick a resistor that would limit the current slightly higher than what's required. e.g. R<=(18-12)/Im. Im=Imax Calculate the power. P=(18-12)*Im. The diode power would also have to be checked. The amount of time we are talking about that power is being applied, calculations will be overkill. Use a metal oxide resistor type. On overload, they act as fuses.

A free-wheeling diode should be added across the relay coils.

You can put these parts anywhere.

The LED would be driven by the relay contacts and would have a series resistor.

There are 4 lead RGB resistors available or 3 lead RG resistors. R&G together give yellow. RGB=Red, Green and Blue.
You can also stick with 2 or 3 discrete colors.

Now, more realistic, less realistic, or different only with two microswitches, you can have RED, GREEN and Yellow. Yellow being a rare even where it did not switch fully.
 
(Latching relay)
They are a signal coil that only uses momentary power to move the turnout. Reversing polarity moves it back. Can this be done some how ? They are twined together so I am using 18 volts dc with a dual button board.

I didn't read, sorry. You just need two extra "steering diodes" and add subtract the diode drop (18-12) becomes 18-0.6-12.
You would route positive pulses to one coil and negative to the other.

There are two techniques running in this thread together. Micro-switch(s) or latching relays.
 
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