dcc directional lighting

[martin_moore]

I have just converted my railroad class 42 benbow to bi colour led lighting have fired up to test and all 4 lights are either all red or all white button 0 changes colour as does direction button.

I think i saw somewhere about changing colour and turning on and off but cannot find this info now any help would be welcome.

My dcc system is gaugemaster prodigy advance 2 , my decoder is tts class 67 this has been working and seems to still be ok as its sitting on my track ticking over nicely but with all lighting wires hanging out.

[Fishmanoz]

Sounds like they are wired incorrectly.  The white decoder wire should go to the white lights at the front and red at the back.  The yellow wire to the red lights at the front and white lights at the rear.

[Chrissaf]

You have used the term "bi colour LEDs".

.

Q1 - Do you mean LEDs that are either white or red depending upon what voltage conditions are applied to it?

.

Q2 - If you do, then do these LEDs have two or three termination legs (wires)?

.

I have come across "bi colour" LEDs that are red, green, amber & yellow, but haven't seen any that are white / red. When you used the term "bi" did you mean that to mean "bi-directional" rather than the physical type of LED.

.

Supplementary question for the sake of clarity:

.

Q3 - You say all four LEDs come on together. You also say the the direction button changes colour. Are there 4 LEDs at each end of the loco (8 in total) OR are there 2 LEDs at each end of the loco (4 in total).

.

I can probably help, but I will need to see a schematic of how you have wired up the LEDs to the decoder.

.

Draw up your circuit with as much detail as possible and post back here as an image using the 'Black and White' hill icon image posting tool. The image needs to be in .JPG or .PNG or .GIF file format and preferably not more than 2MB in size. Unfortunately for you, it is a Saturday. Particularly when posted by newbies, posts with images are held back for authorisation by the forum administrator. Authorisation only happens during normal weekday office hours so an image posted tonight or tomorrow won't appear until Monday.

.

Given that any image you post won't be published until Monday, then If I make some assumptions in the absence of the answers to the questions I have posed above. They would be, the white and red LEDs are separate LEDs and there are 4 LEDs at each end of the loco (2 white and 2 red) making 8 in total for the loco. If these assumptions are indeed correct, then the LEDs should be wired up as follows:

.

/media/tinymce_upload/47e7e0ac7f54b3fdaed40f5670d040ce.jpg

.

If the assumptions I have made are incorrect, then you will have to post an image schematic of what you have wired up for me to assess. I have shown typical Resistor values of 1K (1,000 ohms). The values you have used might be different, include your values in any schematic you post.

.

EDIT: Fishy got in with a reply whilst I was creating my schematic that basically confirms what he has written in text.

[martin_moore]

Hi thanks for replyin, the LEDs are bicolour red and white with 3 legs so all wired so I thought as per diagrams on the net but they are all either red or white the 0 button on my controller doesn't turn them on or off it just changes colour and pressing direction button just changes all colours the same 

[martin_moore]

thanks both of you I obtained LEDs off internet with resisters as well,I thought I had followed one of the wiring diagrams from a well known source but I may have gone wrong somewhere. The LEDs are 3 legged and seem to be red and white both colours are working as I said switching the 0 button on controller either has them all red or all white it doesn't turn them on or off the direction button seems to work as they all change colour when that is pressed but again all the same colour. There are only 4 LEDs 2 each end.I have blue wire in a sort of t shape coming from decoder going to either end through the resisters to the LEDs middle leg. Same for white to shorter leg and same with yellow to longer leg. I really am struggling with all the jargon and instructions for the decoders. It all sounds like gobble degooke. Am I right in thinking that the cvs can be changed somehow to alter lighting as I have some hattons decoders and the instructions seem to point in that direction. I have been running this loco with sound for a week now and seem to be understanding how it works but I am only using the pre programmed functions.

[martin_moore]

Hi Chrissaf I did say above in answer to question 3 there are 4 LEDs in total 2 each end I got these from a well known auction site from layouts for u 3 MM lighthouse bi colour LEDs warm white/red common anode item no 202148549463   3 volt 20ma with cr1/2w 1k5 resisters hope this helps I will try and get wiring diagram on tomorrow many thanks

[Fishmanoz]

There are 2 fundamental things about bi-directional lighting which is a standard feature on all NMRA compliant decoders which are 2-function and above.  The first, not applicable here I think, is that 128 speed steps must be enabled for it to work.  128 speeds steps is the default too.  The second is that F0 turns it on and off, meaning F0 will only ever be used for this, not some other decoder function.

 

Some more advanced decoders do allow function remapping via CV settings, but why you would want to consider this for lights I can’t think.

[martin_moore]

Hi Chrissaf I did say above in answer to question 3 there are 4 LEDs in total 2 each end I got these from a well known auction site from layouts for u 3 MM lighthouse bi colour LEDs warm white/red common anode item no 202148549463   3 volt 20ma with cr1/2w 1k5 resisters hope this helps I will try and get wiring diagram on tomorrow many thanks

Hi Chis sat I got all information out of the book digital command control for railway modellers and he says that the middle leg needs to be positve I asked the question to the supplier are the common legs positive and they replied that they are I quote the middle leg is positive the other 2 negative

[martin_moore]

Hi chrissaf I wish I had found that website as my LEDs are 3mm not 2mm they do look a bit oversized but it's only me who's going to see them.

[Chrissaf]

All the three legged LEDs I have ever used have the negative on the middle leg and have positives on the the outer (colour switching) legs.

.

The decoder has a fixed positive blue wire and uses switched negatives to control the LED switching on and off. So unless you add additional electronics to handle the voltage polarity conversion, you won't have any success using common cathode bi-colour LEDs natively on your decoder as the voltage polarities are incompatible.

.

There are no CVs on any decoder that will change the polarity of the blue wire. CVs can change lighting effects, like make them dimmer or make them flicker for example. But the basic LED wiring MUST be technically valid as a starting point.

.

If you give me the URLs to where you sourced these LEDs from, I might be able to track down a datasheet for them. At least I could then confirm 100% what is or is not feasible as potential circuit wiring. It is always possible that these LEDs are a variation from the norm and use a common positive, but I will need to see the technical specification of the LEDs to confirm. So do please try to post a URL for them.

.

EDIT: After a bit of Googling I have found these Red / White LEDs with common Anode (Positive) on the web site for Express Models. It does state in their description "Made to our specification.........". This statement would seem to infer that Common Cathode (Negative) is indeed the norm. Is Express Models where you got these LEDs from?

.

/media/tinymce_upload/f6a9bc70d1d10f4bb4c4d7b51c31ea1c.jpg

.

[Chrissaf]

Martin,

Taking all the replies written to date into consideration. Plus based upon my own testing this evening of a standard (common cathode) three legged bi colour LED (Red / Green) and the fact that Express Models and Layouts4U both focus on model railway products thus they would know that the decoders are common positive (anode). Then I am comfortable that the LEDs you have sourced from Layouts4U are indeed common anode (positive) and white / red in colour.

.

On that basis, this is how I would see them being wired into your loco and decoder. Review this schematic of mine and check it against what you have wired up and see if it matches. The fact that you have 1K5 resistors as opposed to my 1K0 resistors in the schematic is not an issue. 1K5 (1,500 ohm) values are fine.

.

/media/tinymce_upload/3ecb10bd20ae7f68ab278f2a17b6dd87.jpg

.

I suspect from the observations that you have described in your replies that you have wired both the front and rear LEDs exactly the same. Notice in my schematic, the wiring of the loco rear is reversed compared to the front.

.

When the White wire is switched negative (loco in forward direction). The front White and rear Red LEDs will be on.

.

When the Yellow wire is switched negative (loco in reverse direction). The front Red and rear White LEDs will be on.

.

If when the loco is in forward direction all four LEDs are white. Then reverse the wires to the outside legs of both LEDs at the loco rear.

.

If when the loco is in the forward direction all four LEDs are red. Then reverse the wires to the outside legs of both LEDs at the loco front.

.

Doing that, should either fix the issue completely or at the very least move you in the right direction. 😆

.

You say pressing the 0 button doesn't switch the lighting on and off. I'm assuming that you mean F0. F0 should switch the lighting on and off independently from the forward / reverse loco direction. Being a GM Prodigy Advance I am not familiar with that controller, but looking at the online manual the 0 button appears to be a F0 shortcut button.

.

If it is not switching OFF your directional lights, then there might be a control issue using your Prodigy with your TTS decoder. This following previous post might have a bearing:

.

https://www.hornby.com/uk-en/forum/hornby-tts-decoders-reported-problems/

.

However, not being able to switch them OFF is not as inconvenient as not being able to switch them ON.

 

[96RAF]

I have just done exactly this using 3 legged red/white leds on a Class 40 and a Deltic. Essentially as per Chris last schematic.

 

I will post photos of the circuit and breadboard proof wiring showing them working from the Train PC later. They are 3mm and a bit bright so maybe a higher resistance needed.

 

Rob

[96RAF]

Practical application of Chris's diagram, except I used one resistor per end in the blue wire, whereas two per end would have dropped the intensity.

 

Forwards

/media/tinymce_upload/317b927760bcf31e6c4f3e229240cf83.JPG

 

Backwards

/media/tinymce_upload/36e9c511e8176dbda95cfa08cb534c9e.JPG

 

Too bright - higher resistance required.

/media/tinymce_upload/366116e7b217ec0d087320e89ee265a0.JPG

 

Rob

 

[martin_moore]

I have just done exactly this using 3 legged red/white leds on a Class 40 and a Deltic. Essentially as per Chris last schematic.

 

I will post photos of the circuit and breadboard proof wiring showing them working from the Train PC later. They are 3mm and a bit bright so maybe a higher resistance needed.

 

Rob

Hi Rob can you show close up of your pcb set up as I tried that route but got it messed up I have blank pcb and perforated which I tried. I think I will rewrire as its a real mess also think a trip back to maplin to get a bread board and a look on YouTube for quick lesson in how to use cheers

[Chrissaf]

Another source for 3mm White / Red Common Anode LEDs @ 20p each instead of 50p (Layouts4U price).

.

https://www.rapidonline.com/truopto-osrwpa3132a-3mm-red-white-bi-colour-led-common-anode-3-pin-diffused-76-0017

.

Extract from Datasheet

/media/tinymce_upload/e6fd65de86c453648e6a043f1f7f70b6.jpg

.

[96RAF]

No veroboard or pcb used Martin. Just the breadboard. If you are looking at buying one also grab a box of extra link wires as you soon run out of them even on simple circuits.

 

This is the one I have ...

https://www.maplin.co.uk/p/ad-12-solderless-breadboard-bz15r

And these are the link wires...

https://www.maplin.co.uk/p/jump-wire-kit-fs65v

 

Wires are soldered to each leg of the leds - see data sheet for which leg is which, then the blues had a series resistor soldered in line and both resistors were sleeved amd soldered to the decoder socket pin. The other wires are just cross connected to get the front/rear logic correct and again soldered to the decoder socket per the diagram.

 

The square in my scrawled diagram is actually the inner four pins of the loco decoder socket.

 

You can if desired solder to a bit of vero then to the socket via a 4-pin plug and socket allowing easy separation of the body but in this case these was plenty of room for wires so I just left them long.

 

https://www.maplin.co.uk/p/led-tester-n71au

While you are in Maplins get yourself an led tester. This is a matchbox sized blue box that uses a 9 volt battery to prove leds. Very handy. 

Rob

[NWR-Gordon-4]

Rob, the image of the layout you posted, is that your's?

 

GNR-Gordon-4

[96RAF]

Yes Jacob

[96RAF]

Going back to the lights on all the time problem, I had similar on one installation and found it was a solder bridge on the socket. Easy fixed once you find it.

Rob

[NWR-Gordon-4]

Cool. I like your layout, Rob. Please can post more images of it, in a new topic, of course?

 

GNR-Gordon-4

 

[Chrissaf]

Jacob, look at Rob's signature box at the bottom of any of his posts. There is a clickable link in it, that will take you to Rob's internet site. You will find more photos on there.

[NWR-Gordon-4]

Oh, yes! Thank you for pointing me in that direction, Chris.  😀

 

GNR-Gordon-4