# Need wiring help.



## rzw0wr (Aug 28, 2013)

Below is a diagram of my main control panel.
You can see that some of my track has turnouts at both ends.

My switches are standard DPDT toggles.
My LED are bi-color, red/green.

What I what to do is:
if the entering turnout to a track line LED is green but the exiting turnout light is red, I would like the LED on that track to be red.
If the entering turnout LED is green and the exiting turnout LED is green then the LED on that track to be green.

I have several places on my layout that have this problem.

The problem I am having is that I can't figure out how to wire the LED on the track.

In the picture the turnout LED are circled and the track LED is boxed.

I also attached a diagram of how I plan to wire my turnout switches.
The non-wired LED at the bottom is the one I am have a problem with.

Does any one have any suggestions on how to wire the track LED?


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## JerryH (Nov 18, 2012)

I believe if you use the unused switch contacts from each tortoise machine for the turnout pairing to create another "dpdt switch" to run the conditional track led, you will sort of create a logic device to do what you want indicated.


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## rzw0wr (Aug 28, 2013)

Here is some logic or wiring I have been playing with.
It is an idea and not a schematic.
All the components are not there yet.

Can anyone tell me if this idea will work?
The transistor hook up is what I concerned about.


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## DonR (Oct 18, 2012)

I had a thread here on the Forum some time back that
concerned this very topic.

I have done a bit of research and so far no luck finding.

I have a series of 4 turnouts in one of my mains. I wanted
a signal to show green when ALL FOUR were set for
clear path and red when ANY ONE is set to diversion.
I had available a 1.5 vdc signal from my turnout 
panel to for each turnout.

Gunrunnerjohn gave me a 2 transistor controller that
was the logic. In my case it controlled a red/green LED
in a signal tower, it can also control your panel lights.
It's very simple and easy to wire.

I'll keep searching and post a link when I find it.

Don


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## rzw0wr (Aug 28, 2013)

Don, I remember that thread.
I will search for it also.
Thanks for reminding me.


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## DonR (Oct 18, 2012)

Found it.

If you want to keep your sanity ignore the first pages of
posts but here is the final solution from GRJ.

http://www.modeltrainforum.com/showthread.php?t=15613&highlight=Transistor+circuit+needed&page=6

It was very embarrasing for me when I found that
I had made incorrect connections on the transistor.
That is what caused all of the back and forth.

It continues to work as illustrated in the pics in the thread.

By the way, you can have as many inputs to the logic
as you need, each with a diode.

Don


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## rzw0wr (Aug 28, 2013)

Thanks again Don.
I also found it.


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## gunrunnerjohn (Nov 10, 2010)

If I were doing it today, I'd use FETs and not transistors. No issues with voltage drops.


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## rzw0wr (Aug 28, 2013)

I have to do more testing today however, I think the circuit that grj did for DonR is what I need.
I did figure out that having the LED turn red when both turnouts are red id not a good idea. You would not know if the LED was red because both turnouts were closed or if ton was up and the other closed.
I think I will have the LED turn off when both turnout are open.


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## DonR (Oct 18, 2012)

gunrunnerjohn said:


> If I were doing it today, I'd use FETs and not transistors. No issues with voltage drops.


Oh No, John. I don't even want to think of working on this again.
My signal bridge is working perfectly doing exactly what
I wanted.

But, just out of curiosity, do you have a circuit diagram of
this logic using FETs?

Don


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## rzw0wr (Aug 28, 2013)

Don, John's circuit calls for a 2 lead bi color led.
I don't have any and I don't think Radio shack sells them.

Can his circuit be used or changed to use 3 lead bi color leds?


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## gunrunnerjohn (Nov 10, 2010)

I haven't really drawn anything up for FET's, don't really have a need.


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## DonR (Oct 18, 2012)

Dale

I got my red/green 2 wire LEDs at Radio Shack. They have quite
an assortment, you have to look closely in those drawers.

GRJ would have to redraw the circuit to use 3 wire LED.

Don


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## rzw0wr (Aug 28, 2013)

Thanks Don.
I looked and looked on line for the 2 lead LEDS at Radio Shack.
I finally ordered enough on line.
$.10 each. Went ahead and ordered 100 of them.
I make a lot on mistakes.


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## gunrunnerjohn (Nov 10, 2010)

I keep a generous stock of all kinds of LED's, never know when an odd requirement will come along.


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## rzw0wr (Aug 28, 2013)

Back to Radio Shack.
Yep they gots them there thingies.
Had 2 left, close out item.
A whopping $.12 a piece.
Rewired the circuit for what seems to be the 45th time.
It works great.
The only problem so far that I see is that when both switches are red, points leading to another track, the led in this circuit is red.
I am looking into that to either made it off or something.

Thanks again to John for the circuit and to Don for reminding me.
Great help both of you.


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## DonR (Oct 18, 2012)

Dale

I see you saying there is an anomaly in the circuit operation
on your layout.

From what you say it seems to be showing red when any
turnout is set to divert, just as mine does. Is that not what
you want?

On my main where the signal is located, there are 4 turnouts.
Three of them will cause the signal to show green when they
are set to straight. The 4th one, will permit green ONLY
when set to divert since it is joining 'another' main, Red if
set to straight for the 'other' main. The logic feed to
the transistor comes from my turnout control panel LEDs
which are also 2 wire Red/green.

Don


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## rzw0wr (Aug 28, 2013)

Don, I kinda solved that problem, I made a 2 transistor And gate, hooked it up to the red lights on the switches.
When both turnout lights are red a (for now) white LED will light.
I am still thinking this over but, I am have a fun time.

Thanks again for your replies.


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## DonR (Oct 18, 2012)

I don't have a clear idea of what you intended with
the system, but if it is doing what you want that's great.

Mine was to give a purpose to the signal bridge target
lights; At a glance I would know that there is a clear 
route or not and avoid the need to check each turnout individually.

Don


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## rzw0wr (Aug 28, 2013)

Don, I had a problem in that the bi color led turned red when 2 different conditions were met with the switches.
1) when both switches were not set to divert to another track.
2) when the the switches were both set to divert.

I found this confusing and did not tell me what I wanted to know just by looking at the light.

I added a second off color light(blue) to let me know that both switches were set the same, to divert this track.

In others words I had 2 conditions when the light would turn red.


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## fcwilt (Sep 27, 2013)

gunrunnerjohn said:


> If I were doing it today, I'd use FETs and not transistors. No issues with voltage drops.


A FET is a transistor - a *F*ield-*E*ffect *T*ransistor - of which there are several styles.

I am guessing you are contrasting FETs to BJTs - bi-polar junction transistors.


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## gunrunnerjohn (Nov 10, 2010)

Yes, they're both technically transistors, but they have very different characteristics.


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## DonR (Oct 18, 2012)

rzw0wr said:


> Don, I had a problem in that the bi color led turned red when 2 different conditions were met with the switches.
> 1) when both switches were not set to divert to another track.
> 2) when the the switches were both set to divert.
> 
> ...


It's not possible to guess without seeing your actual circuit and it's
connections to your panel.

You might trace your connections, if you read my travails with the circuit,
you'd find I had made wrong connections. The simplicity of the circuit is
that ANY TIME there is a voltage on the INPUT the LED will go RED, else
it remains GREEN. 

Perhaps you need a diode to block some stray current. Each of my input
lines is protected by a diode.

I also found that resistors in each line reduced the voltage below
that needed to activate the transistor.

Don


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## rzw0wr (Aug 28, 2013)

Yep, that is what it does.
Red if one switch is opposite the other and Red when both switches have the tracked closed to traffic.
Green when track is open to traffic.
Needed some thing to show me that the led is red because the switches are the same to close traffic to this track and not because the switches are not aligned.


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## DonR (Oct 18, 2012)

If I read you right, you should have a diode feed to
the transistor from the RED (divert) panel light of
each turnout. Thus, if either or both are not giving
a clear track your signal shows red. If BOTH are
set for straight there would be no voltage to the
transistor and LED would be GREEN.

Am I stating your situation correctly?

Don


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