Reply to "Legacy Amtrak F40PH Number Board Brightness Fix & Cabbage Unit As Well"

gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

The larger the resistor value for a given voltage, the lower the current and the heat. The resistor value I used results in about .06 watts of dissipation, and it doesn't even get warm.

LED's are current mode devices, and you control the brightness by controlling the current. I dropped the current around 5x to the bulbs. LED's are have fairly linear light output in relation to current. So, dropping the current 5x dropped the light output around 5x as well.

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