Signals, how to wire them?

[Hrw-Amen]

Please note that I no electrician so please make any replies in easy to use lay-man's language.

I have been looking at designs for signals and reading various things both on here and that I have googled, but am a little at a loss to be able to work this out. I have tried numerous variations of wiring using P/F lights and also 9V and 4.5V but cannot figure out how to wire what I want to happen.

I am trying to make a working signal for a siding that I have. Now I don't know much about real signals, but what I want to do is have a simple green light or a red light. I am not worrying about what happens in the real world so please don't hit me with lots of how certain railways really operate the signals. I just want to be able to have a red light on, flip a switch and have a green light on.

I would prefer to use P/F lights and battery box if possible. So the P/F lights have two lights (Which is trains are normally used for headlights.) so how can I wire it up so that only one is on at a time, say in the red light, then flip a switch and have just the green light on? I thought that I may be able to use the switch that we use for changing directions of motors when we place two train motors in the same engine. But all that seems to do is keep both lights on, then switch it and they come back on again.

I am assuming that there must be a way, but I cannot find it. Any help would be appreciated. I do not mind cutting wires and re-wiring them like I did in my 4.5V motors to run with the I/R unit. But if cutting is required I will buy a short extension lead to cut rather than the actual P/F unit, be that lights, I/R unit or whatever.

What I am really hoping to do is have a small shunter on the siding waiting, have the signal at red, then when I get the train to move at the same time change the signal to green.

I do not mind buying an IR Unit as then I can change the setting for the signal to match whatever channel the waiting engine is on in order to pick it up and change them.

Any ideas of how to wire this in really simple steps using only proper LEGO (Preferably P/F.) parts?

Thank you for your help, only my eyes are hanging out from staring at the screen most of the day trying to find what I am looking for without success.

[Spitfire2865]

May I ask why you want to use only Lego parts?

[Locomotive Annie]

May I ask why you want to use only Lego parts?

Don't go there it's a Lego thing.

Hrw-Amen, are you wanting the signal to operate with the points that lead into the siding or are you just wanting an off/on type setup?

I did something like this for my kids with their H0 layout when they were small and as I remember it wasn't terribly hard to do,

Edited March 11, 2013 by Locomotive Annie

[peterab]

I would prefer to use P/F lights and battery box if possible. So the P/F lights have two lights (Which is trains are normally used for headlights.) so how can I wire it up so that only one is on at a time, say in the red light, then flip a switch and have just the green light on? I thought that I may be able to use the switch that we use for changing directions of motors when we place two train motors in the same engine. But all that seems to do is keep both lights on, then switch it and they come back on again.

I am assuming that there must be a way, but I cannot find it. Any help would be appreciated. I do not mind cutting wires and re-wiring them like I did in my 4.5V motors to run with the I/R unit. But if cutting is required I will buy a short extension lead to cut rather than the actual P/F unit, be that lights, I/R unit or whatever.

What you want to do is possible, but I'm pretty sure it's not possible without cutting up the PF lights if you want to use them.

Please note that I no electrician so please make any replies in easy to use lay-man's language.

Any ideas of how to wire this in really simple steps using only proper LEGO (Preferably P/F.) parts?

I can explain it to you, but it will require me to speak about polarity, diodes and rectification, I'm happy to explain these as I go. Unfortunately jargon is required when you are dealing with concepts that laymen rarely encounter.

If you'd like me to I can, but not until I get back after work tomorrow since I have to go to bed now due to an early start in the morning.

[Werlu Ulcur]

But if you put the lights on the same channel as engine A, the green light will always be on as long as the engine is running, won't it? So if engine B comes up to the same place and you want it stopped at the red light, if engine A is running somewhere else the signal will be green and not red for engine B .

I understand you wanting to use a Lego solution but wouldn't it be easier/simpler if you just wired the signal to go red or green at the flip of a switch? Of course I'm assuming here you have where to route wires; if not you would have to use a wireless solution and that might complicate things a bit.

[Hrw-Amen]

Spitfire 2865: I want to use only LEGO parts because it is a LEGO set up, made of LEGO parts.

Werlu Ulcur: OK, yes I see what you mean. I think what I am trying to get at is that when the light on the signal goes green the engine in the siding can move off. Perhaps it would be easier to just have a switch next to the signal (Or at least nearby somewhere.) that I can flip to change the signal from red to green and back again. Not quite the solution I was after but I guess that would still do and as you point out I can then changed it back again if needs be.

Peterab: Well I do not mind cutting wires on cheap'ish P/F parts, as I said I have used extension cables and cut them rather than say cutting a cable attached to an IR Unit for example. I guess lights are reasonably cheap so if that was the only I suppose I could do that. What I want to avoid doing though is cutting cable son the expensive bits like motors, IR Units and stuff. I know when I was a kid and my father and I had a model railway we used to have switches that we simply flipped the switch and the signal changed from green to red or the other way. I think that they had three wires, one main one from the battery (My father used a car battery for all the lights.) and then a single one for each bulb. I think the switch then used the main power line and changed between the secondary ones for the bulbs to change which one was on.

I think what would be really good would be to have a double one that when it changed to green on the siding it changed to red on the main line. Then when it changed to red on the siding it changed to green on the main line?

Locomotive Annie I just would like to have it changed with the point, but as I do not have electric point motors yet, I think I would for the on/off functionality right now. Maybe in the future tying it in with point operation would be good. You are right I am pretty sure that is how we had it set up on our old model railway when I was younger.

I think that the problem I am coming up against is that there are two bulbs on the P/F cable and they seem from what I can work out have to both be on at the same time, whereas what I want to do is to have one of them on, then flip a switch, turn the first one off and switch the other one on. Is that possible? If so maybe a diagram of how to wire it would be useful so long as it is simple and not filled with technician speak.

I did also try with some old 9V stuff I had lying about but the lights I had only seemed to flash on and off for ever. I do not really want to use the 4.5V stuff I have as the battery box is huge as are the lights themselves.

Anyway, lets see what people can offer please?

[Werlu Ulcur]

Take a look here, this might be useful.

[Konrad]

Thats going to take some hacking thats for sure

[kieran]

The main issue you will have with the LED lights as they come out the box is that they are set-up with the use of rectification to be on when the power is set for forward or reverse. This will make it very hard to set one to be on at a time with out some modification. For a LED to light you have to pass electricity into the LED in one direction, reverse will not light the LED like it would in a regular light bulb. I am afraid you will need to change the set-up of the LEDS to achieve what you want, unless you are happy t use 2 sets and a IR receiver, in which case you can have blue on or off and red on or off for green and red on the LEDS.

if you don't mind changing a PF LED then you can remove the centre block and rewire the leds with new resistor and you could make one come on in forward and one in reverse if that will be acceptable for you?

[Pet-Lego]

If you are going to use two lightposts, one for the main line and one for the siding, then with two pair PF-lights you can set this up. Have from PF-lights A go one to the red on the siding and the other led to the green on the main line and from PF-lights set B one LED to green on the siding and red on the mainline. You'd need two switches though to turn the LED's on, turn A on turn B off and visa versa. If you remove the rectifier from the PF-lights you can use the reversal switch, to switch between PF-light set A or B with just the one switch.

The best looking solution though would be to remove the rectifier from the PF-lights (I believe it's situated in the 2x2 plate around the middle of the wire) and at the same time switch the left and right wire connection of 1 of the LED's. So for this solution I think you only need to take apart the 2x2 plate in the middle of one of the wires.

[peterab]

Both kieran and Pet-Lego are correct. I'll do a step by step to explain what you'd need to do to make these work the way you want them to.

If you take a look Werlu Ulcur's very useful link, there are four pictures. The top one shows the PF light disassembled to reveal the circuit board, next is a close up of the circuit board with the components labelled, next the circuit diagram, and finally the circuit layout.

The first thing you'll notice on the circuit layout is the lights are symbolised by little triangles with arrows emerging from them. This tells us they are light emitting diodes. Diodes have the property that they allow current to flow in only one direction (ie they have a polarity). When the polarity is correct LEDs light up, otherwise they don't.

You'll also notice four more diodes in a small square on the circuit diagram. This is a rectifier bridge, the purpose of which is to correct the polarity of the incoming power, to the required polarity. Ie if the polarity is incorrect, it rectifies it. It should now be obvious why the PF lights don't work as you expect.

As Pet-Lego suggests one solution is to remove the rectifier from the circuit, an then jumper C1 and C2 to + and -. After doing that you'll have two lights that will both work when the polarity is correct, and not otherwise. If you now swap the direction of one of the LEDs you'll have what you want; one LED will light up for each direction of the current.

Just one final warning, unless you're soldering skills are pretty good you'll find it difficult to solder the jumpers on. If so I'd probably just replace the circuit with larger components on a breadboard (this is kieran's suggestion), but you'd probably be better off going the whole hog and buying some LED's and just cutting up an PF extension wire to get the plug in that case.

If anything is unclear just ask and I'll try to clarify.

Edited March 12, 2013 by peterab

[Hrw-Amen]

I may end up having to just use very small bulbs like I used to on the N-Gauge layout as I am pretty sure I know how to wire them up with a two way switch like we used back then. (That is if I can get those small bulbs nowadays?) I think they called them 'grain of wheat bulbs' so some googling may be involved. The only trouble with them is they can get rather hot even though they are tiny.

It is a pity as I really wanted to keep it as a LEGO solution, but looking at these wiring diagrams and talk of bridges and rectifiers has me lost. I am sure it is simple once you know what you are doing, but is a bot overwhelming when you have no idea. I just imagined that the LEDs would be wired in the same way as old fashioned light bulbs, but evidently not.

I will see what small bulbs I can find at some point over the next couple of weeks,

Thanks for your suggestions anyway. Now i know that I in fact I have been left behind and know nothing about modern electronics!

[Werlu Ulcur]

Why not go for LEDs instead of bulbs?

[Spitfire2865]

LEDs are very easy to work with. You just need to make sure everythings wired in the right order.

[Hrw-Amen]

I got the impression from reading the advice from people that if I used LEDs I would need to include all of these other bits mentioned such as 'bridges' etc that I have no idea of what they are for and how they work or how to wire them in.

I did look at the circuit diagrams from the link but to be honest I was a bit at the a loss as to what all the symbols mean? They are not the same as when I did basic electronics (In physics lessons at school in the 1970's.) when i was younger.

I thought after reviewing this the above comments that it maybe better, if not exactly what I wanted, to stick with what I know. As I do not know about these other components needed with the LEDs I think it best to avoid them until I find some simple diagrams of how to wire them up. After all I don't want to start a fire in my house.

I guess I have to accept that I am just an old person who has lost touch with modern technology. (Although I hoped that would not be for many years, it seems to have come earlier than I hoped for.)

[Spitfire2865]

Some companies do sell pre wired LED assemblies. I have bought some from Radio Shack and they are simple plug and go. Would recommend those to someone who isnt all that knowledgeable in LEDs. But also, bulbs WOULD worl, and would be much easier, but the size is what probably is a problem for Lego sized trains. One reason why LEDs are so great. Hope I can help.

[1974]

All this can be achived with (single) 9V lightbricks, cables and switches. You'd need one switch for red and one for green though. They can be coupled through a few gears so you only need to flip one lever. If you want to use a PF batterybox, get the conversion cable

I prefer using lightbulbs over LEDs anyway. Don't like the cold white light and I find the old 4,5/12V lightbricks charming and fun to build with, but 9V surely is the easiest (and cheapest) to deal with. I also use 'grain of wheat bulbs', fits snugly into Technic bricks and comes in all sorts of sizes/voltages (some a good deal smaller than LEGO LEDs, but of course does not have an equal light output)

If you need some, let me know Some even comes prewired

And if you like I can show some examples tomorrow

Edited March 13, 2013 by 1974

[Paddyb98]

Just out of curiosity, would something like this be a viable option for a person with little soldering skill?

http://compare.ebay.com/like/390500701174?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar

[Phoxtane]

What about wiring up two differently colored LEDs to some sort of three-position switch, with one position being the red bulb, the middle position being off, and the third position being the green bulb? As far as I know, you'd only need some resistors if you're running the setup off a battery pack.

[1974]

Just out of curiosity, would something like this be a viable option for a person with little soldering skill?

http://compare.ebay....mTypes&var=sbar

Not those, they're UV. Seller has other colours in his shop allthough I do not think a battery solution is a good idea

What about wiring up two differently colored LEDs to some sort of three-position switch, with one position being the red bulb, the middle position being off, and the third position being the green bulb? As far as I know, you'd only need some resistors if you're running the setup off a battery pack.

That would be very simple indeed, but too easy and not enough LEGO for me

[Hrw-Amen]

Phoxtane: Yes, I am reasonably certain that is what we did on the old N Gauge layout. We got a load of three way switches from a car repair shop and used wire stripped from old telephone cables. (My father was in the building trade so could get a lot of it free.) then we just wired them up so that one way was red, the middle off and the other green. That is what we used the 'Grain of wheat' bulbs for. That is about the extent of my electrical knowledge. I did consider it but wanted to use PF bits if possible. It looks as though it may come down to this though.

1974: I did look at 9V lights although all the ones I have seem to be double flashing ones rather than single light elements. I have a couple of old 9V battery boxes and have no issues using these as they are real LEGO, I even have a supply of a few of those plates with the contacts in them to use rather than wires. I may have a look on Bricklink to see if I can find any single 9V lights. The same with the old 4.5V ones, I have one or two of them and a spare 4.5V battery box so if I got a few more of those 2X2 red/yellow light bricks I could probably get that to work I think. I am not sure but is it possible to connect the 4.5V ones so that the signal would show red when the leaver was pushed one way and green when it was pushed the other? Again I have to go to Bricklink to get enough actual lights to try it out.

Paddyb98: So do those LEDs have all the stuff needed so that one could simply attach them to a battery and switch and they can be switched on and off, or do you have to be able to put in all these other components that are in the PF lights? If they can be just attached to a battery and work that maybe an answer but again like the 'grain of wheat' bulbs and car switches it is not very LEGO.

We will have to see, I'll have a poke about on Bricklink and see what lights I can find and then give it another go before resorting to non LEGO parts. Perhaps if someone knows off the top of their heads the Bricklink part no's. they could post them. I am sure I can find them if not but it may save me a few minutes if you are just aware of them?

[1974]

1974: I did look at 9V lights although all the ones I have seem to be double flashing ones rather than single light elements. I have a couple of old 9V battery boxes and have no issues using these as they are real LEGO, I even have a supply of a few of those plates with the contacts in them to use rather than wires. I may have a look on Bricklink to see if I can find any single 9V lights. The same with the old 4.5V ones, I have one or two of them and a spare 4.5V battery box so if I got a few more of those 2X2 red/yellow light bricks I could probably get that to work I think. I am not sure but is it possible to connect the 4.5V ones so that the signal would show red when the leaver was pushed one way and green when it was pushed the other? Again I have to go to Bricklink to get enough actual lights to try it out.

Hrw-Amen, what you have is this :

http://www.bricklink...Item.asp?P=4771

In one direction it's constant light, flip it and it's blinking light. Not good for your project

You need this :

http://www.bricklink...Item.asp?P=6035

The old 4,5V bricks can be used with 9V, but you'd have to put two in series. Again, not suitable for you project (you also need to source those hard to get/costly connectors)

I have actually done exactly what you want with 9V light bricks and switches (allthough they're somewhat costly) :

http://www.bricklink...Item.asp?P=6551

I don't think you should dable with the coloured 4,5/12V lightbricks, but just use 9V lightbricks with a coloured front tile/plate whatever

Really, it's just easier to stick with 9V (and that can be connected to PF at then with an official cable)

My custom lightbricks are just really an extension of that idea ..

Another idea is to use selfcontained lightbricks :

Yellow :

http://www.bricklink.com/catalogItem.asp?P=54930c02

Red :

http://www.bricklink.com/catalogItem.asp?P=54930c01

And then mechanically couple them as you please

Paddyb98: So do those LEDs have all the stuff needed so that one could simply attach them to a battery and switch and they can be switched on and off?

That is the 'problem', yes it would work, but you need non LEGO switches and a bit of soldering. Easy and doable, but not very LEGO. Imho that is

What non LEGO elements we like to use is _highly_ personal, though. I'm an electrical engineer and allround wiz. I could have trains controlled from outta space running at 600 miles per hour with buildin flatscreens, running water while twittering to your grandma all controlled by an app build into my eyelid .. But it wouldn't be LEGO would it?

[Hrw-Amen]

Yes that does look like the 9V ones I have. I will seek some single ones out on Bricklink. Also I did not think about using those self contained light bricks. I have a couple built into my station building for lighting. I don't switch them on much so am not sure what the battery life is like in them? I guess they would have the same problem as the 4.5V lights in that they are quite bulky, whereas the 9V ones are reasonably small and can easily be concealed within a signal. The self contained and 4.5V ones would require a large ungainly signal to conceal them.

If/When I get something working I'll post some photographs.

Thanks everyone for the help and talking through the various options.

[1974]

The battery in those selfcontained lightbricks will not last long, about a day (12 hours?) :

http://www.eurobricks.com/forum/index.php?showtopic=37471

And quite cumbersome to change

Let me know if you got more questions. I'll show some of my custom lightbricks in the near future ..

[Paddyb98]

Well, for the record, I get that what I was doing wasn't very Lego (I'm not a purist at all). However, I was planning to put them in buildings so you could see the inside from the outside. They would go in something like the Grand Emporium, where normal Lego LED'S would be able to get the job done.

Edited March 13, 2013 by Paddyb98