# Lighting with no decoder...is it possible?



## cbarm (Apr 15, 2011)

Im curious if its possible to have loco lighting in a dummy without a decoder? Ive been using 0402's and wondered if I could wire em to a rail wiper with a 1000K ohm resister?


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## DonR (Oct 18, 2012)

DCC tracks are a modifed AC, so in addition to
the resistor you'll want to use diodes to rectify
the current. 

Install wipers on all wheels so you'll have
flicker free lights.

Don


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## wvgca (Jan 21, 2013)

you would also need a bridge rectifier to convert DCC to DC, and maybe a smoothening capacitor .. resistor would be needed to drop from about 15v to what the leds need , but 1000k would be too high .. 1k would be closer


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## gregc (Apr 25, 2015)

there's no need for a bridge. Use half the resistor value. try it. no need for the extra parts

most LED display intensity is controlled by the duty cycle -- the percentage of time the the LED is on versus total on + off time.


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## wvgca (Jan 21, 2013)

gregc said:


> there's no need for a bridge. Use half the resistor value. try it. no need for the extra parts
> 
> most LED display intensity is controlled by the duty cycle -- the percentage of time the the LED is on versus total on + off time.


true enough... 
I never use Led's with AC, never though of that option


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## daschnoz (Dec 12, 2016)

If nothing else, I would still use a single diode (1N4001 or similar) and 1/2 wave rectify the Ac voltage. The PIV (peak inverse voltage) of most LEDs isn't more than a couple of volts.

Add a resistor in series with the diode (1k).

If you're like me and hate LED flicker, add a filter cap across the LED and its series resistor. Something in the 47uF range should be sufficient (make sure that the cap is rated for 30V minimum). If you do this, increase the resistor to something closer to 1.5k (I wouldn't go lower, slightly higher is ok).


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## gregc (Apr 25, 2015)

if the reverse voltage of the LED is an issue, you would wire a regular diode across the LED in the reverse direction. this prevents the reverse voltage across the LED from being greater than the normal forward diode drop (~0.7v). Or you could just use another LED.

With DCC operating at over kHz, i don't think flicker will be a problem.

While it's alternating, it's a square wave.

use some clip leads to try it. I just did


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## santafealltheway (Nov 27, 2012)

cbarm said:


> Im curious if its possible to have loco lighting in a dummy without a decoder? Ive been using 0402's and wondered if I could wire em to a rail wiper with a 1000K ohm resister?


I found a roll of LED strips on ebay from china, they light up on dcc track in either direction, you dont need a rectifier or anything. 20 ft roll was like, 3$ shipped.

pretty sure this is it.

http://www.ebay.com/itm/Led-Strip-L...512604?hash=item1c641a0adc:g:Q-AAAOSw-0xYP~2w


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