TMCC headlight question

Tom DenselOGR Forum Member SUPPORTING MEMBER

I am converting the headlights in a K-Line diesel with TMCC to LEDs. This locomotive has the original Lionel motherboard with the reciever, Railsounds card and Railsounds power supply. The headlights are wired directly to the motherboard, there are no auxillary driver boards for the lights. When I checked the voltage on the headlight wires I was only getting 0.5 volts dc, Is this correct? The original grain of wheat bulbs worked fine before I removed them. I installed Evan Designs Universal LEDs and get nothing. I tried a 16V grain of wheat bulb and it did glow, however it was very dim. Are these motherboards designed to drive LEDs directly? Do I need to get plain LEDs and install the proper resistors and diodes? Any help would be appreciated.

Thanks,

Tom

2/16/145:40 PM

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GGGOGR Forum Member

Normally in command mode the R2LC is putting out half rectified sine wave and the R2LC 08 it's the bottom half of the sine wave. So you need to check polarity, you need a current limiting resistor, and you also need a resistor across the output because the LED don't draw enough current to keep the triac conducting. If you do a search, folks have provided the specific info needed to do the conversion. May be in the Electrical section. G

2/16/148:57 PM

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Tom DenselOGR Forum Member SUPPORTING MEMBER

Thanks G.

I put a 510 ohm resistor across the leads and the lights came on. I figured someone on the forum has addressed this issue before.

Tom

2/16/1411:14 PM

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GGGOGR Forum Member

Glad you got it. G

2/17/148:25 AM

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