Flicker free LED lighting question

[farrellaa]

 I saw a listing for these capacitors on Ebay and they indicate they can be wired to a passenger car LED light to maintain power thru turnouts or dirty track. Is this all I would need is the capacitor wired in series with the LED's? Just seems too simple.

SMD storage capacitor 470 uF 16 VDC

  -Bob

[richg1998]

farrellaa

 I saw a listing for these capacitors on Ebay and they indicate they can be wired to a passenger car LED light to maintain power thru turnouts or dirty track. Is this all I would need is the capacitor wired in series with the LED's? Just seems too simple.

SMD storage capacitor 470 uF 16 VDC

  -Bob

 

With a few other components. This is rather an older site but it can get you started.

http://www.awrr.com/lighting.html

Some now use super caps. Much smaller with much more capacitance.

http://www.members.optusnet.com.au/nswmn/flicker_free_JB.htm

Super caps can be bought via ebay from China. A few buy them to build their own stay alive modules for DCC decoders.

Rich

[RR_Mel]

I’ve tried several circuits to stop the flickering over many years and finally went to battery powered lighting.  It’s a pain you know where but pretty much all non flickering passenger car lighting is just that.  Some work better than others but the best I came up with is a 1 fared 5.5 volt super cap powered through a full wave bridge rectifier in series with a 1k resistor and a 5.1 volt zener diode but even that has it’s problems.  I use 8 to 10 low level warm white LEDs with 10k resistors in each passenger drawing a total of 3 to 4ma.

 

 

There is very little ambient light, the LEDs are actually quite dim.

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[farrellaa]

Mel,

That is nice lighting in your SP car. I have tried several resistor values and the 2-3K range seems right to my eyes. I have been installing the adhesive strip SMD warm white LEDs in my Walther's cars and they look quite good and for the most part don't flicker much. I know wiper styles have an effect on how steady they light as well. I guess I will have to live with it for now until I settle on a 'circuit design' that I am comfortable with building. I do remember riding the NYC along the Hudson River many years ago and the lights would flicker every so often, just like my HO versions?

   -Bob

[RR_Mel]

Bob

 

As a kid I road the UP City of Los Angles and the SP Golden State.  Memories of a 12 year old kid at 78 can be off a bit but I don’t remember the lights flickering so I made my Daylight passenger cars so that they won’t flicker.

 

My Mother, brother and I got stuck in deep snow at Donner Pass December 21, 1949 for about 10 hours.  Everything held very good, didn’t get cold and lights stayed on.  The SP sent a snow blower up to Donnor Pass from Sacramento to get us going.  Quite a thrill for a 12 year old, not so much for my Mother.

 

I have two cabooses with the super caps that do pretty good, no flickering through turnouts and I keep my track super clean for my DCC operation.  They work good enough for me so I don’t plan on changing them.

 

After screwing around with lighting for several years and not liking how the lighting looked I revamped all of my passenger cars for battery power, I didn’t like the first try with a battery in every car.  Turning them on and off was a real problem. The original design used micro switches under the cars, pain in the you know what turning them on and off.  Next I tried latching reed switches just below the roof, they aren’t reliable.

 

Next try was a E7B battery/charger unit powering my existing 1½ volt GOWs, too much current at 1½ volts.

 

My final attempt looks very promising, 8 to 10 flat wide angle warm white LEDs operating with 10k resistors off 4 volts from my E7B battery/charger unit with a relay to turn on and off the lights controlled by Function 3 on the E7A.  Total current is under 50ma at 4 volts.  Each car draws between 1 to 4ma with two exceptions, the observation car draws the most at 17ma (taillights) and my ¾ Dome/Lounge draws 6ma.

 

I installed a latching reed switch across the relay contacts for testing, took over five reed switches to find a reliable one.

 

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[DigitalGriffin]

 

 

The solution is very similar to the above, except you can optionally drop the diode from the capacitor lead.  But you have to insert a 1kOhm resistor before each LED.

 

[Mark R.]

A very extensive, in-depth discussion recently on this very topic ....

http://model-railroad-hobbyist.com/node/23755

Mark.

[hon30critter]

Mark:

Thanks for the link.

Dave

[mlehman]

Bob,

Down the page in this part of my Night Scene thread, I discuss my car lighting.

http://cs.trains.com/mrr/f/88/t/213765.aspx?page=2

There's a circuit digram in there somewhere.

I tend to use segments cut from LED light strips for mine. The 470 uf cap i the one I use most often and is commonly available, although sometimes I use a smaller one when space is an issue. With the LED strip segments, I've used resistance of up to over 100,000 ohms. Dimmer is better in most cases IMO. Much of the commerical car lighting is unprototypically bright, I guess so that it's obviously lit even with room lights on, but I like it dim...

[MisterBeasley]

farrellaa

Is this all I would need is the capacitor wired in series with the LED's? Just seems too simple.

Well, it is "too simple."  Capacitors are DC devices, as are LEDs.  I'm not sure about those particular capacitors, but if they are electrolytic they are polarized, like LEDs, and you must get your plusses and minuses correct.  And, they would go in parallel with the LED-resistor combination, not in series.

If you are running DCC, you have a square wave coming in from the tracks, and you should add a bridge rectifier to get DC out of it.  Likewise, DC provides +/- in one direction and -/+ in the other.  The rectifier will take care of that, too.

[TheWizard]

 

This is the diagram I used for my passenger cars. They light the athearn shorties very nicely, and will work on just about any mess of dirty track. As far as LED's, I used a spool of outside LEDs from Amazon for $12. I think they're designed for 12v, but they work well and have a prototypical brightness.

Here's an album of my cars. http://imgur.com/a/obSJx

[Mark R.]

TheWizard

 

This is the diagram I used for my passenger cars. They light the athearn shorties very nicely, and will work on just about any mess of dirty track. As far as LED's, I used a spool of outside LEDs from Amazon for $12. I think they're designed for 12v, but they work well and have a prototypical brightness.

Here's an album of my cars. http://imgur.com/a/obSJx

 

You used 15,000 ohms for R2 ? Was that used to dim the LEDs to create a "glow" ? 

Mark.

[hon30critter]

TheWizard:

Thanks for sharing your lighting diagram. Based on your pictures it works very well.

Dave

[TheWizard]

Mark R.

 

TheWizard

 

This is the diagram I used for my passenger cars. They light the athearn shorties very nicely, and will work on just about any mess of dirty track. As far as LED's, I used a spool of outside LEDs from Amazon for $12. I think they're designed for 12v, but they work well and have a prototypical brightness.

Here's an album of my cars. http://imgur.com/a/obSJx

 

 

 

 

You used 15,000 ohms for R2 ? Was that used to dim the LEDs to create a "glow" ? 

Mark.

 

Yes. The cars are just kinda sorta visibly lit with the lights on, and when you turn the lights off the cars have a very even glow without being overbearing like the MTH or Walthers lighting kits.

I'm sure you could play with the resistor to increase brightness, but then they wouldn't stay "on" as long if the track power gets cut. As they are now, they take a second or two to "charge", but remain on for about 30 seconds before they start to dim, and take about a full minute before they go out.

[Mark R.]

TheWizard

 

This is the diagram I used for my passenger cars. They light the athearn shorties very nicely, and will work on just about any mess of dirty track. As far as LED's, I used a spool of outside LEDs from Amazon for $12. I think they're designed for 12v, but they work well and have a prototypical brightness.

Here's an album of my cars. http://imgur.com/a/obSJx

 

I've used that identical circuit in my cabooses with one alteration - I used a 5 volt 1 farad super cap. R1 was calculated to drop the voltage to safe limits to use the 5 volt cap and R2 just made up the difference (R1 + R2) for the LEDs.

Many people have told me it shouldn't work like that, but I built it back when these super caps were something new (13 years ago) and just "assumed" my logic was correct. Thirteen years later, these lit cabooses are still running and working !

Mark.

[DigitalGriffin]

Mark R.

Many people have told me it shouldn't work like that, but I built it back when these super caps were something new (13 years ago) and just "assumed" my logic was correct. 

 

Yep.  Shouldn't matter as long as R1 << R2 and ALL your LEDs are in parallel (since you are using a 5V super cap)