help with cab lights dcc

[cornishmick]

Hi im in the middle of converting a lima class 47 ss Great Britain to dcc i have got a set of dcc head and tail lights which are nearly finished and look great but my question is about cab lights.

 

I am thinking of buying 2 cab light units and was wondering how to instal ie when wired in with the function butons can they be indervigerly be turned on or will they work the same end as the directional lights any help would be great

 

Thanks mike

[davyjcrow]

Mick, that really depends on what you want to do with the cab lights and also how many spare decoder outputs you have.

 

Assuming you're using a 4 function decoder, and that the yellow and white wires are used to install the directional lighting, that would leave the green and purple wires (usually functions 1 and 2 respectively on the dcc handset) to control the cab lights individually.

 

If you don't have the spare functions (i.e. because the tail lights are wired for individual control using the green and purple wires already, or your decoder has less than 4 function outputs), then yes you could wire them up with the headlights for each end. It might be better to wire in series with the headlights since wiring in parallel can cause problems when using different types of LED together (current hogging by one LED at the expense of the others can be evident, causing either the headlights or the cab light to be extinguished or very dim when operated together).

[cornishmick]

Mick, that really depends on what you want to do with the cab lights and also how many spare decoder outputs you have.

 

Assuming you're using a 4 function decoder, and that the yellow and white wires are used to install the directional lighting, that would leave the green and purple wires (usually functions 1 and 2 respectively on the dcc handset) to control the cab lights individually.

 

If you don't have the spare functions (i.e. because the tail lights are wired for individual control using the green and purple wires already, or your decoder has less than 4 function outputs), then yes you could wire them up with the headlights for each end. It might be better to wire in series with the headlights since wiring in parallel can cause problems when using different types of LED together (current hogging by one LED at the expense of the others can be evident, causing either the headlights or the cab light to be extinguished or very dim when operated together).

Hi thank you for that I will be useing a Hornby 4 function decoder and I hoping to have the cab lights seperate from the directional lights. Will the head and tail lights have to be wired to 2 seperate functions or can they be wired to 1 I'm new to dcc and still learning have been a dc biff for years but now converting slowly all the help I can get is very much apriceatededMany thanks for tour helpMike

[Brian]

Hi

Conventionally...

Wire the white light at one end and the red lights at the other end of the loco to the decoders white wire (Negative - Cathode).

Wire white light at the other end and the red lights at its opposite end to the Yellow wire (Negative - Cathode). Share the Blue wire (Positive - Anode) between all lights. Then 'F0' on the console turns all these lights On/Off and the locos direction setting swaps them around automatically.

 

If you want both ends cab lights to come on together wire the Green wire to both ends cab LEDs (Negative - Cathode) and again use the Blue wire for the Positive. 'F1' then turns the cab lights On/Off

 

If you want each ends cab lights to be separately switched On/Off, then wire one cab end to the green wire and the other cab end to the Purple wire (Negatives) and connect the Blue wire (Positive) to both ends. Then 'F1' will switch one cab end On/Off and 'F2' will switch the other ends cabs light On/Off.

 

Note: the Blue wire is a Positive - Anode supply and is common to all the function wires.

 

My web site shows the various combinations and by looking at the two function decoder the wiring for the front and rear lights is perhaps easier to understand? http://www.brian-lambert.co.uk/DCC.htm#Decoder%20controlled%20lighting

 

 

Edited to add URL

[ThaneofFife]

Is

 

Hi
Conventionally...
Wire the white light at one end and the red lights at the other end of the loco to the decoders white wire (Negative - Cathode).
Wire white light at the other end and the red lights at its opposite end to the Yellow wire (Negative - Cathode). Share the Blue wire (Positive - Anode) between all lights. Then 'F0' on the console turns all these lights On/Off and the locos direction setting swaps them around automatically.

If you want both ends cab lights to come on together wire the Green wire to both ends cab LEDs (Negative - Cathode) and again use the Blue wire for the Positive. 'F1' then turns the cab lights On/Off

If you want each ends cab lights to be separately switched On/Off, then wire one cab end to the green wire and the other cab end to the Purple wire (Negatives) and connect the Blue wire (Positive) to both ends. Then 'F1' will switch one cab end On/Off and 'F2' will switch the other ends cabs light On/Off.

Note: the Blue wire is a Positive - Anode supply and is common to all the function wires.

My web site shows the various combinations and by looking at the two function decoder the wiring for the front and rear lights is perhaps easier to understand? http://www.brian-lambert.co.uk/DCC.htm#Decoder%20controlled%20lighting


Edited to add URL

Can I just check - is the blue a common positive on Hornby decoders?  Sure Ive read these are the only ones that dont have a blue common + feed.

[Adrian Wintle]

Can I just check - is the blue a common positive on Hornby decoders?  Sure Ive read these are the only ones that dont have a blue common + feed.

Yes, that is a DCC wiring standard.

 

Further to the above, if you want the tail lights to be switchable (on when light engine, off when pulling a train), then you will need two more functions to control them (for a total of six).

 

Adrian

[AMJ]

If you were to use a different chip some of them include the ability to have the aux 1 & 2 directional by tweaking a few of the CV values. 

 

As this is one of your first hardwire installations keep it simple to and you can make changes at a later date.  As it's a LIMA there will be ample space inside the body so you could even do all of your wiring onto a mini circuit board - you can get a 21 pin board with solder points from various including ESU.

[newbryford]

Is

 

Can I just check - is the blue a common positive on Hornby decoders?  Sure Ive read these are the only ones that dont have a blue common + feed.

 

As already mentioned, Hornby decoders are standard common positive - it's just that they managed to do their lighting circuit boards as common negative (unless sound fitted) making them a right PITA to modify to individual switched tail lights.

 

Cheers,

Mick