I just read the increased current in DCC can cause incandescent lights installed in cars, such as the light kits in my Kato passenger cars, to get hot to melt the plastic. Can anyone confirm or deny this?
(I am just glad I read this before I made the move.)
Richard
Yes, incandescent bulbs generate heat more than does an LED, but the amount of current they draw will be no different whether using DC, AC, or DCC power. The amount of heat generated will depend on both the current and voltage, with the main difference being that DCC puts a constant voltage on the track.
Whether they get hot enough to melt the plastic depends on their current draw and how close they are to the plastic.
I still don't fully understand voltage vs. current. My father has teach me multiple times, and I did pass my college physics course, but it just doesn't seem to stick.
Think of a garden hose with no nozzle on the end. If you turn it on, the water comes out with a certain pressure, and it takes you some length of time to fill a bucket. Pressure is like voltage. If everybody in town is watering their lawns, pressure is reduced. The flow rate (gallons/minute) is like current. The faster the bucket fills, the more current you've got.
For light bulb heat, what counts is power, which is the product of voltage times current.
It takes an iron man to play with a toy iron horse.
Incandescent lamps can cause issues. I remember that the P2K SD60's melting the cab roofs due to 'hot' headlight bulbs. DCC track power is about 13-15 volts - A little higher than straight DC. Check with Kato about how their lighting units handle this. The 'function output' in most DCC decoders is about 12 volts, but it is a full 12 volts....
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
The biggest issue is the constant on nature of DCC and the fact that it often runs by default at constant 14.5 volts YMMV. The incandescent bulb that was properly engineered for a 12.5 volt MAX but typically operated at a little more than half that is going to exhibit some undesired characteristics at a constant 14.5 volts. Even if it doesn't melt the plastic, it will likely make it brittle, etc over the long term. Best to do something to correct it and drop the heat back down.
Another related issue are constant brightness circuits, if the installation has them for DC.
Mike Lehman
Urbana, IL
Trains with DC never get to 12 volts. If they do, they are on the floor, pretty quick.
Constant brightness light bulbs with DC are 1.5 volt bulbs.
With DCC, there is a constant 12 to 14 volts to the bulb which can cause plastic to warp or melt a little unless the trains came with 1.5 volt bulbs. This has happened to some.
No doubt, this can vary with different model train manufactures.
I belong to a number of train forums and have seen this issue before.
LED's are the way to go.
No idea how much current is required for those passenger cars. Sometimes that can give you an idea of what the heat might be like.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Although i didn't get melted plastic, I got my share of burned bulbs since I put DCC decoders in my fleet of locomotive.
Guy
Modeling CNR in the 50's
Some DCC systems run a little higher DCC voltage which can result in a higher light voltage.
Light voltage from a decoder is many times not regulated.
A current surge occurs every time the light comes on which will shorten a light bulb life.Think of how many times you reverse the direction of the loco.
Some who use 12 volt light bulbs put a 22 ohm, ½ watt resistor in series with one light lead to reduce the surge effect and prolong light bulb life.
RideOnRoadI just read the increased current in DCC can cause incandescent lights installed in cars, such as the light kits in my Kato passenger cars, to get hot to melt the plastic. Can anyone confirm or deny this?
This was a Rivarossi with factory lighting. It might be an extreme example but....
_______________________________________________________________________________________
Seconded. Current is the amount of water in the hose; voltage is the pressure pushing it.
Stu
Streamlined steam, oh, what a dream!!
DCC only provides a percentage of track voltage. I would say about 1 volt less than track voltage--this reduction is due to the power consumption of the decoder. So, if your incadescent bulbs were fed directly by track voltage and you put in a decoder they should actually be cooler.
Yes but standard DCC track voltage compensates for that. Most systems put about 14-15V to the rails for HO scale.
OK so maybe the buylb runs at 1 volt under its rating. That's STILL more than it typically would get on DC - how much are you running around at full throttle?
But it's also not ALL bulbs. Those old 12-14V large bulbs, yet, they get HOT. There are 16ma and 30ma bulbs that don;t get nearly as hot, also 1.6V 15ma bulbs - those can usually be installed in direct contact with plastic with no ill effects.
LEDs are still the better option though, no heat and they last forever. Athearn seems to be one of the last holdouts. Genesis locos at least should come with LEDs, not those silly bulbs. Ulrich has refit kits for some Genesis locos that replaces the bulbs with LEDs and makes for a much nicer model.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker Yes but standard DCC track voltage compensates for that. Most systems put about 14-15V to the rails for HO scale. OK so maybe the buylb runs at 1 volt under its rating. That's STILL more than it typically would get on DC - how much are you running around at full throttle? But it's also not ALL bulbs. Those old 12-14V large bulbs, yet, they get HOT. There are 16ma and 30ma bulbs that don;t get nearly as hot, also 1.6V 15ma bulbs - those can usually be installed in direct contact with plastic with no ill effects. LEDs are still the better option though, no heat and they last forever. Athearn seems to be one of the last holdouts. Genesis locos at least should come with LEDs, not those silly bulbs. Ulrich has refit kits for some Genesis locos that replaces the bulbs with LEDs and makes for a much nicer model. --Randy
I've seen DC systems put out almost 20volts at full throttle. So, at part throttle could easily be 12V. Point being he may not have a problem. LEDs last longer, run cooler, but don't look the same--depends on what you want.
DCC is an square wave AC current. As a result, bulbs connected straight to the track will both burn brighter and hotter and have a shorter life.
converting the current to DC via a full wave bridge rectifier will reduce some of the heat. But it will also reduce the brightness considerably.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!