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Using LED Lights For Model Passenger Trains
Club member Trevor asks readers for advice with his LED lights:
“Recently I installed lighting inside a couple of passenger train cars using the new led strip system. It worked perfectly until the train started to move and then the LED’s started to flicker which ruined the effect. I have a DCC system, and my track is clean. I have new wheels and pickups so I’m not sure what the problem is. I would appreciate any guidance from others who have experience using LED’s on their trains. Thanks in advance.”
Please add your comment if you think you can help Trevor.
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8 Responses to Using LED Lights For Model Passenger Trains
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To over come the flickering problem with pick up from DCC system is that the track is alive with Digital AC current so over come this fit a 25 Micro farad capacitor and a diode to the system inside the coach before the power gets to the LEDS as they are made to run on DC current this will replace the ac with DC just for the LEDs and will not affect the DCC operation. Make sure the + lead of the capacitor is connected to the anode of the diode and the positive voltage is connected to the positive lead if the lights also make sure that the voltage is not exceeded to the ratings of the LEDs.
I agree with Kevin The capacitor is the way to go it is like the capacitor that are installed as part of some DCC Chips. I am no expert on it yet but I know enough that this is the fix. from Newman
In addition low power 3-pin voltage regulators may be used after diode bridge and capacitor but they will provide lover voltage than the supply and a bit of complication for non-electronic person. Help can be obtained by some nearby experienced friend in rearranging the LED strings to match with the output DC voltage. Although LEDs are current driven devices but regulated DC will be fine and simple for our applications.
I have a pair of Triang suburban coaches with lights running on DC, and 7 yellow LEDs one per compartment per coach. I have rectifies and resistors on board and I crammed the biggest capacitors I could find into the guards compartment and the flickering is minimal when everything is nice and clean. However I use Hornby Dublo metal bogies with Romford top hat pinpoint bushes and Lima wheels, and have wires soldered to the bogie frames to take current to the LEDS. These soldered joints fatigue in time and come loose causing flickering, the wheels get dirty and the pin point bearings need oiling with non insulating lube. As you have DCC I would cram the biggest electrolyic Capacitors I could hide in parallel with your LEDs and downstream from the decoder anything over 5 volt should be fine. If you go before the decoder you need 24volt if not 36 as these mothers explode when excess voltage is applied.
Ensure the capacitor is correctly wired as well. Incorrect polarity will result in explosion as well. Not good in your favorite model, I found out this little pearl in a 12 fluroscent light I was working on, fortunately nothing else was damaged as it was on the bench doing the final test before assembly.
1) Clean your wheels ! The rim of the wheel picks up dirt, resulting in bad contact.
A brass wire brush is good, better is a rotary brass wire brush on a dremel. This really polishes them.
2) Clean your track. Almost any cotton cloth or paper tissue will work, solvent is optional, methylated spirit is or lighter fluid are good (but flammable !). (Personally I disagree with track rubbers as I think they just leave particles of grit and rubber on the track.)
3) Electrical pickup: best place for this is to have the wires soldered to small brass or nickel silver springs resting on the axles. This avoids axle to truck contact problems.
4) DCC puts AC on the track, so ideally: 4 diode bridge => capacitor => lights
5) What era are you modelling ? Now when I was a lad (men start saying this when they get over 50), I seem to remember the lights did flicker as the train went along the track, so this could be a realistic feature !
Capacitor on input side of car lighting system:
Voltage: 25V or above
Capacity: 25uF is good, get 100uF in if there’s room.
(Bigger is better considering how much space is available.)
Type: Electrolytic (as high capacity is needed)(ensure correct polarity)
Alternative type: Tantalum (which are smaller for the same capacity)(ensure correct polarity)
A full bridge rectifier before capacitor will protect it from exploding due to wrong polarity. There is slight voltage drop but changing values of resistors in series with LEDs works well.