The use of LED's for

Locomotive Headlights

Bright enough to give a good reflective light for the driver and are easily seen by bystanders.

Advantages, no heat to speak of, so plastic lens work, low current drain and long life.

To power one white Luxeon LED from approx 12 volts, use a 33 ohm 5 watt
resistor in series
To power two white Luxeon LEDs in series from approx 12 volts, use a 22 ohm
5 watt resistor in series
To power three white Luxeon LED in series from approx 12 volts, use a 10 ohm
2 watt resistor in series

Or use LM317 three-terminal adjustable regulator as a constant current
source (current sense resistor = 4.7 ohm 1/2 watt)

Some details of the white LED lamp (headlight)

Luxeon Star/O part number LXHL-NW98

lens diameter 21.5 mm = 0.846"

square base 25mm x 25mm = 0.984" x 0.984"

overall height 15.7 mm = 0.618"

max current @ 25 degrees C (80 degrees F) = 0.35 Amps

max temp 75 C (plastic lens) = 170 degrees F

max current at max temp (75 degC) = 0.25 Amps

25 lumens output @ 1 watt input (similar to 2 watt halogen lamp if you could
find one)

half-power beam angle approx 10 degrees

about $US 15 each

www.lumileds.com

Distributed by Future Electronics

Seattle area store
12100 North East 195th Street Suite 150
Bothell, Washington 98011
Tel.: (425) 485-6616
Fax: (425) 483-6109

or buy online from www.futureelectronics.com

by Bruce Wilson of the British Colombia Society of Model Engineers (B.C.S.M.E.) Burnaby (Vancouver) Canada