# Led flicker on HO Locomotive



## Weshathcock (1 mo ago)

Hi all. So I have a old Marx HO engine that came with a E5 condesent bulb. I replaced it with a 12-16 volt screw in LED. So now I have flicker and its dim as the locomotive goes around the track. My question is what size capacitor should I use to stop the flicker? And how should you wire them? Thanks ahead of time.


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## T-Man (May 16, 2008)

It makes no sense what you did. The engine is DC correct? Probably runs at less than 8 volts. You placed an LED with a resistor, to up it to 12 plus. No wonder it dims. 

Try a normal LED with a bridge and capacitor, it will cut out the flicker by operating at a low voltage of three volts. An ebay step down converter will work. I use 1 amp diodes and 330 uf capacitor. Your 12 volt set up would require one much larger cap and the same cost as the step down converter.

I tried to fix the problem like that in o27 and used a 2200uf cap. in a lighted caboose. It did not eliminate all the ficker.
I have not seen it in years.

The cap may not fit in the tender.

Maybe you could improve the electrical connections of the engine to eliminate the flicker,
Have you run the engine a lot? Old engines get oxidation at the joints and a good workout with oil will help clean them up.
You could add another car with rail contacts.


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## Dennis461 (Jan 5, 2018)

Does it flicker in both forward and reverse?
Bulb make and model number please!


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## Weshathcock (1 mo ago)

So, I bought these lights because they were recommended. Most likely the wrong lights. I can use them else where if they will not work with














out a bunch of hassle. The loco has been cleaned and all that good stuff.


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## Weshathcock (1 mo ago)

Hey all. Happy New Year. Ok so a tech guy said to use a 5-10uf 20-30v capacitor in parallel to stop the flicker. Just wanted everyone to know. I'm going try it and let you guys know what happens.


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## CTCLibby (17 d ago)

*Weshathcock*: I suspect that the incandescent bulb was flickering also - you just can't see that because it takes longer to cool down whereas the LED will turn off immediately; in each cycle coming from the transformer. I would wonder about the quality of the connections from the track to the bulb. Wheels clean, track clean, all solder connections bright and shiny?

Later


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## Dennis461 (Jan 5, 2018)

Weshathcock said:


> Hey all. Happy New Year. Ok so a tech guy said to use a 5-10uf 20-30v capacitor in parallel to stop the flicker. Just wanted everyone to know. I'm going try it and let you guys know what happens.


*STOP*
The capacitor will explode when you reverse the voltage.


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## MichaelE (Mar 7, 2018)

If an electrolitic, it might. But a ceramic disc cap?


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## vette-kid (May 2, 2020)

Those bulbs are great on DCC. DC, as mentioned you will need a lower voltage bulb unless you run full power all the time

Sent from my SM-G781U using Tapatalk


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## Weshathcock (1 mo ago)

Dennis461 said:


> *STOP*
> The capacitor will explode when you reverse the voltage.


Will do. I guess I will return the capacitor and search for the condesent bulb. I bought those LEDS because that's what I was told to buy. I figured the person who recommended them had used them before.


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## Lemonhawk (Sep 24, 2013)

LED's will last virtually forever so it was the right choice, you just need a little electronics in front of the LED.


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## MidwestMikeGT (Jan 4, 2021)

Weshathcock said:


> Will do. I guess I will return the capacitor and search for the condesent bulb. I bought those LEDS because that's what I was told to buy. I figured the person who recommended them had used them before.


Like @T-Man said, consider placing a bridge rectifier between the input leads and the capacitor, (noting the polarity of the bridge rectifier). In parallel, solder the leads to the LED. You should be OK then.

Here is a YouTube video (but he does not have the capacitor).
How-to #5 - DC Locomotive LED Install

This is the rectifier I use:
Major Brands DF01M Diode Rectifier Bridge, Single, 100 Volt, 1A, 4-Pin, DFM Tube, 3.4 mm H x 8.51 mm L x 6.5 mm W (Pack of 20)

And the capacitor I use:
uxcell Aluminum Radial Electrolytic Capacitor with 2200uF 16V 105 Celsius Life 2000H 10 x 20 mm Black 15pc

You can probably find smaller capacitors to fit your purposes.

Hope this helps.


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## wvgca (Jan 21, 2013)

a bridge rectifier will not only take care of any 'ripples' but the LED will last longer if it is fed with DC voltage .. LEDs don't really like AC voltage with the swings and things, lol


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