Chapter-6j-1 Page 41
Carriage Lighting
If you run a night time scene and have people in the carriages then why not provide lights for them This is easy to organize with DCC power as the track voltage is always there. Power is picked up from the bogie Wheel-set. The simplest pickup is a phosphor bronze wire rubbing on the axles, when only one wheel is insulated. Inset is an Athern bogie set with plastic body and only one wheel on each axle is insulated. The front bogie picks up from one rail, the rear from the other.
Components:
Depending on the DCC voltage 6 or 8 white LEDs can be powered per carriage. If you are doing a multi carriage consist, then consider running a pluggable wire along the consist to connect together all the pickups to give flicker free lighting. The circuit is very simple. The positive going DCC pulse feeds the regulator LM317 which supplies a constant current through the string of LEDs. Two strings can be fed from the regulator. The current and therefore the brilliance of the lights can be controlled by changing the 330R resistor. A higher resistor value gives less brightness. Each LED will drop 2 to 3 volts depending on the current. The regulator needs
Resistors, 2 of 10 Ohms, [10R] 1 of 330 Ohms, [330R] Capacitor, 0.1 ufd LM317 IC Regulator X marks a LM317L for N scale copper strip Strip board to suit and white LEDs
cut about 3 volts to operate therefore if your DCC voltage is set to 12 volts then only 3 LEDs can be driven in each string. The PC board can be glued or taped to the inside roof of the carriage and 2 wires dropped down to the pickups. The strip to hold the LEDs can be cut from strip board, 2 holes wide for strength, and the LEDs soldered along it. Remember to cut the copper under each LED. LED life is a function of the current applied and LED quality.
If you run N scale carriages you can make your own board. Scribe through the copper on a thin plain laminate board that is about half the size of the strip board and drill it to accept the components. Using the smallest possible components a very small board can be made that will fit under the roof. The 10 ohm resistors in this case are mounted off the board. Either in the leads (as the picture) or in the string with the LEDs. The regulator is the smaller LM317L which is low power and can only handle 100ma. The LEDs will only draw 20 to 30ma in each string so will not overload it.
Tiny N Scale board – top and bottom..
