Model railway help

Thread Starter

RobertB72

Joined Feb 6, 2021
37
I’m designing a small model railway and want to use some led’s to make working signals
I’m going to mount two sets of signals at everywhere that the track splits at each set of points
Consisting of a red and green led on each post just simple traffic lights really
I want it so that a route can be seen but every set of these I’ve seen just indicate green to whatever way the point is set where as I want it that if the preceding point is set the other way any subsequent points will show red

I’m thinking of using on/on switches
Wiring each output terminal to one red one green from opposing signals
And then taking the negative of the green to the feed of the next switch
So that can only be green if the preceding switch is green and then linking the reds from the other feed so as soon as the first red is lit all following reds will be lit but can join this string at any point so the preceding ones won’t be lit but the following ones will be lit

at the end of the strings the negatives from the reds will just be earthed but the last green will feed a small string of leds to illuminate a panel for some sort of route display

I’m quite new to this although I think I have a reasonable understating of this
 

Attachments

wayneh

Joined Sep 9, 2010
17,152
I’m thinking of using on/on switches
So fully manual operation?

One thing you'll hear a lot around here is "use a microprocessor". I happen to think this is one time that it would be a great choice. The Arduino is a common suggestion for beginners and I'd be surprised if your application hasn't already been worked out. Might be worth a look.

In your system, would it be useful to have a single pushbutton (momentary switch) that moves the green light one position at a time? I think that would be fairly easy without a micro.
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
So fully manual operation?

One thing you'll hear a lot around here is "use a microprocessor". I happen to think this is one time that it would be a great choice. The Arduino is a common suggestion for beginners and I'd be surprised if your application hasn't already been worked out. Might be worth a look.

In your system, would it be useful to have a single pushbutton (momentary switch) that moves the green light one position at a time? I think that would be fairly easy without a micro.
The switching will be done via accessory switches that clip on to the point motors so as I change the way the point is set at the lights will change if that point is actually changing the route if it’s behind a point that is already set the other way the signal won’t change until that point is set
If that makes sense
 

eetech00

Joined Jun 8, 2013
2,352
I’m designing a small model railway and want to use some led’s to make working signals
I’m going to mount two sets of signals at everywhere that the track splits at each set of points
Consisting of a red and green led on each post just simple traffic lights really
I want it so that a route can be seen but every set of these I’ve seen just indicate green to whatever way the point is set where as I want it that if the preceding point is set the other way any subsequent points will show red

I’m thinking of using on/on switches
Wiring each output terminal to one red one green from opposing signals
And then taking the negative of the green to the feed of the next switch
So that can only be green if the preceding switch is green and then linking the reds from the other feed so as soon as the first red is lit all following reds will be lit but can join this string at any point so the preceding ones won’t be lit but the following ones will be lit

at the end of the strings the negatives from the reds will just be earthed but the last green will feed a small string of leds to illuminate a panel for some sort of route display

I’m quite new to this although I think I have a reasonable understating of this
Hi
In my former life, I used to design RR traffic systems and may be able to help. I think if you provide a sample track layout it would help understand your intentions. Railroad signaling usually consists of at least 3 colors: red, yellow, green, although I understand you want to keep it simple by using two colors.
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
I haven’t got a set layout design yet as still in planning stage
But will probably be a set of points off the mainline to possibly 4/5 sets off of that line
As I build it il post it but won’t be for a little while yet
 

eetech00

Joined Jun 8, 2013
2,352
I haven’t got a set layout design yet as still in planning stage
But will probably be a set of points off the mainline to possibly 4/5 sets off of that line
As I build it il post it but won’t be for a little while yet
OK...Sidings would be good to know as well.
It doesn't need to be detailed, just show track/siding lines, switch and signal locations.
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
OK...Sidings would be good to know as well.
It doesn't need to be detailed, just show track/siding lines, switch and signal locations.
This is just a quick sketch
I will be using peco switches that attach to the point motor
They are on / on type switches
So the first feed will be 9v dc
The two outputs will power a green and red light at point one A and B
But the next switch will only be powered from the green light so latter points can’t be green unless the preceding one is also green
I have numbered the points 1-4 and gave each exit A-B where the signals will be

so say point 1 is set straight
A will be green and B will show red
Both signals at point 4 will take a feed for the red lights off of point 1 b as because that is red no train will move at point 4

now point 2 will take a feed from the green at point 1
Let’s say this point is set straight
A will show red and B will show green
Point 3 will take the feed from the green at point 2b to feed into the switch at 3
I know I might have to use some diodes in this setup
 

Attachments

eetech00

Joined Jun 8, 2013
2,352
This is just a quick sketch
I will be using peco switches that attach to the point motor
They are on / on type switches
So the first feed will be 9v dc
The two outputs will power a green and red light at point one A and B
But the next switch will only be powered from the green light so latter points can’t be green unless the preceding one is also green
I have numbered the points 1-4 and gave each exit A-B where the signals will be

so say point 1 is set straight
A will be green and B will show red
Both signals at point 4 will take a feed for the red lights off of point 1 b as because that is red no train will move at point 4

now point 2 will take a feed from the green at point 1
Let’s say this point is set straight
A will show red and B will show green
Point 3 will take the feed from the green at point 2b to feed into the switch at 3
I know I might have to use some diodes in this setup
Asumming there is no relative scale in your drawing, is this an "interlocking", or "main line track with spurs/turnouts?
Basically, the difference is, there are no block occupancy track sections between switches (the switches are all interlocked).

Just a word on terminology to keep me from getting confused.

Switch position "Normal" = switch is lined straight

Switch position "Reverse" = switch is lined with turnout

Signal indication "Clear" = green
Signal indication "Stop" = red

Do you plan to indicate track occupancy?
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
Asumming there is no relative scale in your drawing, is this an "interlocking", or "main line track with spurs/turnouts?
Basically, the difference is, there are no block occupancy track sections between switches (the switches are all interlocked).

Just a word on terminology to keep me from getting confused.

Switch position "Normal" = switch is lined straight

Switch position "Reverse" = switch is lined with turnout

Signal indication "Clear" = green
Signal indication "Stop" = red

Do you plan to indicate track occupancy?
Switches are all interlocked
Just one block of power for the whole of that section in the pic

no plans on track occupancy
I just want to be able to glance at the signals to get an idea of what route is ‘live’
 

eetech00

Joined Jun 8, 2013
2,352
Yep that’s exactly how I visualise it
OK.

The next thing we need is a table describing the light status based on the logical switch states.

Going forward, I'll call a electrical switch a "switch" and a track switch a "turnout".

What type of switches will be used to represent the state of each turnout?
Or will the switch actually control the position of the turnout?
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
OK.

The next thing we need is a table describing the light status based on the logical switch states.

Going forward, I'll call a electrical switch a "switch" and a track switch a "turnout".

What type of switches will be used to represent the state of each turnout?
Or will the switch actually control the position of the turnout?
The turnout will be controlled using a double solenoid point motor either peco or hornby and attached to these peco make a switch that is changed whenever the point motor is activated
Because these motors only need a brief pulse of power I have got some
(On) off (on) toggle switches I think I’ve used the right terminology for momentary switches
These use 15v ac so there will be two seperate circuits under the track

one that’s controls the power to the point motors
And a seperate circuit that controls the signals probably just using a battery for this
So even though the switches are connected physically to the motors there is no electrical connections
 

Deleted member 440916

Joined Dec 31, 1969
0
One problem I can think of is I believe the switches on the point motors are only single pole changeover. Each signal may require an inverter stage (either transistor or inverter chip) to enable its aspects to change with only a single wire changeing state.
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
One problem I can think of is I believe the switches on the point motors are only single pole changeover. Each signal may require an inverter stage (either transistor or inverter chip) to enable its aspects to change with only a single wire changeing state.
I have the option of using these

one is a single pole on on switch the other uses 2 single pole on on switches

I have had success with the single switch and 2 signals
By wiring the red led from one signal to the same pole as the green from the other signal And vice versa

so the signal at turnout 1A is green and point 1B is red
And then when the turnout is changed 1A is red and 1B is green

But if I use that method on all signals
If turnout 1 is set straight
There will still be a green signal showing at turnout 4 either A or B depending which way that turnout is set

91B5F3BB-D7C3-4BEF-A53E-0D9ABD9071A4.png

21E6B290-870D-4123-A436-B0DFC8846620.png
 
Last edited by a moderator:

Deleted member 440916

Joined Dec 31, 1969
0
Ahh, the over-centre switches are really nice, the slide switches only work sometimes depending on gauge (hence how much throw) so what gauge are you ?
For your other problem you have to wire the switches in series to make one dependent on the other just like the real points.
 

Thread Starter

RobertB72

Joined Feb 6, 2021
37
Ahh, the over-centre switches are really nice, the slide switches only work sometimes depending on gauge (hence how much throw) so what gauge are you ?
For your other problem you have to wire the switches in series to make one dependent on the other just like the real points.
Yeah the making one dependent bit is the hard bit
I can work out how to make that wotk for some aspects of it
Ie if I run the lead from the green led so that becomes the feed for the next switch but if that signal is red then the next signal is unlit on either red or green
I’m trying to devise a switching option so if one side of the turnout is set to red all subsequent turnouts show red at both sides of the turnout
I’m thinking of using the leds at these signals wired up to the previous red with diodes I can feed power into a string of them halfway along and only light up the following ones if that makes sense
 

Deleted member 440916

Joined Dec 31, 1969
0
Yes the number of diodes can get rapidly out of hand, an alternative is to use a microprocessor with plenty of pins as I did here signalling article but only if you are comfortable with programming.
As for the diode method imagine each point having an spco switch then wiring them in series exactly as your track diagram with the leftmost pole grounded, now each right hand tail wire will only be connected to ground (or - whatever you want to call it) when the points are set for that route. If you take each signal led pair, make them common anode with a single resistor to + then when you ground a signal wire the led will light. Now you arrange small diodes (eg 1N4148) with the anode to the signal wire and cathode to the point wire, best to make a cross hatched piece of paper to show each connection required. Where only a single signal is connected to a point wire no diode is required, the diodes prevent reverse feed conflicts when more than one point wire drives a signal.
 
Top