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By Doug Stoll   Installing LEDs for Headlights

The LED (light Emitting Diode) has been around for decades and some have converted their locos and cars over to LEDs for reliability, realism and constant lighting. Hardware is simple, inexpensive and modifications can be reversible in event owner wishes to resell as original.

If you are running AC like older American Flyer and Lionel locomotives, a simple resistor is sufficient to control the input preventing burnout. AC has a wave that holds a signal that flips direction (wave) every 60 seconds (cycles). The LED is a diode that operates on half of the signal and deadheads the voltage on other half. If the polarity on AC reverses due to directional change, it does not matter to the diode. The LED burnout can happen if the voltage that enters the diode (forward voltage) exceeds the rating of the diode causing the brightness to decay and eventually burn out the diode. If the voltage is DC coming in, the light will simply not work in one direction. Solution to both issues is a full bridge rectifier before the resistor feeding pure DC to the diode regardless of the track output to the loco.

The components required are shown on the right. The longest lead on the LED is called the anode (+) and the shortest lead is the cathode (-).