Wiring bulbs for DCC

Mr Grumpy

Mr Grumpy

Western Thunderer
I posted this request for help on my workbench thread, but have had no response, so possibly it needed to be here!
I'm building a DJH class 47, and have their lighting kit which includes bulbs rather than LEDs.
I will be using an XL V4 decoder, and am not sure how to wire up. Will I need the diodes? Will I need resistors?
I want to install so that the loco lighting is independent, so the rear lights are out when pulling a train, and head code out when stabled.
Here is the DC diagram.
Any help appreciated!
image.jpg
 
Steph Dale

Steph Dale

Western Thunderer
Richard,
I suspect you'll find the wiring diagram that's in with your decoder to be more useful - you won't need the diodes, but will need resistors. I'll have to remind myself what resistance and rating to use (although that info may be in the decoder manual too).
Steph
 
simond

simond

Western Thunderer
Mmm,

Not sure!

You'll surely need the resistors, unless your chosen decoder is able to regulate output voltages - otherwise you'll blow the bulbs. Indeed, you may do both to get the required brightness.

Most decoders provide a blue common and a yellow and white for the front & rear headlights, which is fine, but you will need to use another pair of outputs to drive the loco taillights, to allow them be switched independently.

So for example

White A end headlight
Green A end tail light

Yellow B end headlight
Purple B end taillight

Blue common for all

Not sure if green and purple are the easiest to use, but I hope it makes sense anyway. Choose other free colours if more convenient.

Then you map the green and purple to the direction, and to a common function button. So if the function is on, the rear light is lit, and if not, it's not. You might have to program them so the red and white aren't on at the same end!

And if stabled, choose the appropriate direction, turn the taillight on, and the headlights off.

HTH
Simon
 
Steph Dale

Steph Dale

Western Thunderer
LEDs will save you some current and 'Golden White' or similar can look very much like conventional bulbs...

Steph
 
Mr Grumpy

Mr Grumpy

Western Thunderer
Thanks Steph,
The lighting kit was quite expensive so I will check out the instructions for both, and try to weigh up the pros and cons of each.
 
simond

simond

Western Thunderer
LEDs & resistors are cheap. Is there a second hand market for the lighting kit?

Best
Simon
 
Steph Dale

Steph Dale

Western Thunderer
Richard,
Aaah, yes, I'll bet it was. Shame it wasn't more clearly marked up as being 'not (really) suitable for DCC'. Even if you use the bulbs I still don't think you'll be using much of the kit!
Steph
 
simond

simond

Western Thunderer
Probably can return it as " not fit for the purpose for which it was purchased". Might be worth asking if they'll refund you.

Best
Simon
 
Cliff Williams

Cliff Williams

Western Thunderer
It is easy wiring lights up to an XL V4 card. I use 12volt incandescent bulbs which can be turned down to give that dull yellow effect.
Interesting to note drivers tell me they used to fit 240volt bulbs into the headcode boxes of diesels which only deliver 110 volts.
This is why LEDs for me are just too bright and do not portray the locos as they were.
 
Steph Dale

Steph Dale

Western Thunderer
Cliff,
The problem is that DJH supply 1.5v bulbs to get constant lighting on analogue control.
And you can easily dim LEDs to make them less bright...
Steph
 
Steph Dale

Steph Dale

Western Thunderer
Cliff,
It's just a CV change to dim the outputs. You still need any resistors because the lines can still kick out around 18v, but adjusting the dimming values does work once the LEDs are installed.
Steph
 
Cliff Williams

Cliff Williams

Western Thunderer
No I don't it's straight on to the card.
I tune the lighting levels using the lokprogrammer on scale of 1 to 31 , makes set up so much easier than typing in high number cv values for auxiliary outputs, plus they are then hard set to that level.
 
Steph Dale

Steph Dale

Western Thunderer
Here's the other side of the page, with the diagram for fitting LEDs. I'll have to check my stock, but think I'm normally using values around 1K, rather than the 470 shown; well within the tolerances stated on the previous page (470-2K2 Ohms):
Capture01.JPG

Steph
 
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