What voltage is the dcc chip pushing through to power carriage lighting

[Scubaphot]

I'm dabbling with installing carriage lighting to my dcc layout ! I understand which wire does what but what power is the chip pushing out ?

[Chrissaf]

The blue positive common return wire is permanently at between 12 volts DC and 14 volts DC.

 

The switched negative function wires on the decoder [white, yellow, green and mauve / purple] are zero volts when enabled and 'floating voltage' when disabled [enabled and disabled via the appropriate function command being sent to the decoder].

 

Unless the decoder specifications state differently, then assume that you cannot draw more than 100mA through a decoder function. Thus your carriage lighting needs to be designed to draw less than 100mA. In fact the lower the better, to minimise the stress on the decoder, I suggest a design criteria current value not more than 50mA. LEDs require current limiting resistors in their circuits and the value of these resistors can be used to control the current being drawn. A typical LED will function more than adequately on a current of 3 to 5 mA each.

 

Let's say just for example that you are going to use the mauve / purple wire for the carriage lights. Then a circuit schematic something like this would apply:

 

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[Flashbang]

In addition to Chrissaf excellent details, don't forget LEDs are polarity conscious devices. They must be connected the correct way around or they wont illuminate.

Single LEDs have one lead longer than the other and this is their Anode (Positive) connection. They also have a small "Flat" on one side which is above their Cathode (Negative) lead.

The Blue Function wire is of course Positive to all other function wires, regardless of their colour.

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[Scubaphot]

Thanks gents just what I needed

Keith