I'm new to DCC. I intend to put a decoder into a Model Power Metaltrain F7. I have no idea whether the headlight is 12V or 1.5V or even an LED. How can I determine what it is?
Dean
30 years 1:1 Canadian Pacific.....now switching in HO
Take a look at how it's wired. If this is a straight DC locomotive, and the bulb comes on when the engine is on the track, it's probably wired directly to the power from the rails and should be a 12-16 volt bulb. If there is a circuit board, then it might be anything.
You can see inside a LED, and you will see some metal shapes. Also, the LED will be plastic, not glass.
I suspect this is a simple bulb. My recommendation, regardless of what is in there now, is to get a "golden-white" or "yellow-white" LED and a 1K (1000 ohm) resistor from your LHS, and use that for your headlight. It will last forever, give you a nice bright beam, and look much better than the original equipment.
It takes an iron man to play with a toy iron horse.
mactier_hogger I'm new to DCC. I intend to put a decoder into a Model Power Metaltrain F7. I have no idea whether the headlight is 12V or 1.5V or even an LED. How can I determine what it is?
1) Check the instruction sheet or specs for bulb replacement information. Model Power might be able to help you if you don't have the paperwork any more. http://www.hoseeker.net/lit.html has done an outstanding job of compiling and creating a repository of instruction sheets and catalogs for the model railroad hobby.
2) Open up the locomotive. You can tell by looking whether it's a bulb or an LED. A 1.5 volt bulb typically has 4-6 diodes in a constant voltage setup to supply power to the bulb. A 12 volt bulb in a DC locomotive is directly wired to track power - although the wiring may pass through a circuit board. You can even measure the voltage to the bulb with power applied to the wheels.
Fred W
If in doubt always use a 1k ohm resistor or close for starters. If it's too dim then decrease the value to 680 ohms, and if still too dim decrease again until you hit the right brightness. Also never run a bulb at maximum brightness because it reduces the lifespan.
Springfield PA
Thanks for the info guys!