Re: 12 volts bulb and DCC

Dale Gloer
 

A 12 volt lamp connected to a DCC decoder will likely melt a plastic shell.  This is because the lamp is operating all the time at approximately 12 volts that is supplied by the decoder.  The reason it does not happen on DC is that the lamp seldom or maybe never operates on 12 volts - it operates on whatever voltage is supplied to the motor to make it run at the speed desired, maybe as low as 6 to 8 volts.  A locomotive on DC with 12 volts supplied will run at very high speed. 

In my opinion it is better to replace the lamp with an LED and suitable current limiting resistor when operating on DCC.  Some decoders are equipped with lamp outputs specifically designed for LEDs and do not require an external resistor.

Dale Gloer

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