Light Flicker 2

[emkay_777]

I am trying to resolve a light flicker problem as well, and I came across the thread 'light flicker' which helped a little, I guess.  I've installed the Kato 11-210 LED kits in a couple of trains, and of course, they flicker.  I'm running straight DC.  Is there a way to add a capacitor to make a stay alive circuit on this non-DCC system?  Thanks,

 

Evan

 

[Kiha66]

Before doing anything, get some rubbing alcohol (IPA) and a paper towel and wipe down the track.  Then put some IPA on a paper towel and lay it over track, then put each coach on it and run it back and forth till the wheels are clean.  I've found doing this before running removes flicker and the cars don't require modification.  You'll be amazed how much gunk comes off the wheels.

[emkay_777]

Yes, I've certainly done that, but invariably the problem reappears as the track gets dirty again.  

[cteno4]

Evan,

 

yes you could install one across the led leads, but before the resistor to the led. this is side has already been rectified worth a bridge diode in the beginning of the circuit and resistor keeps the discharge from being too fast and bright (ie flickering brighter).

 

if you can take a picture I could try to find where it would go in.

 

due to the shape of the light board and space you may need to wire the cap back somewhere else in the car (hopefully hidden). You can use smaller tantalium brick capacitors that have a denser charge and rectangular shape or can or disc electrolyinvs that are inexpensive but not as good change density and drum Shape is not as volume efficient to store in the car.

 

i agree with kiha, cleaning track is a chore but a necessary one that may solve the problem and once flickering starts engine sputtering is close behind! And it only gets worse then it gets into the engine and eventually muck city picking up more and more puzz

 

cheers

 

jeff

[emkay_777]

 

So it's the 11-210 lighting kits that I have installed (in the 223 commuter) that I am wondering if a stay-alive type circuit can be added.  The ones I have are in both the powered and non-powered coaches.  The board is pretty small so retrofitting, if possible, looks to be a challenge.

 

 

[Kiha66]

Here is where you need to attach the wires to a capacitor to add keep alive functionality.  Its a small soldering job, but doable.  Make sure the capacitor is rated for more voltage than your track power, and if polarized make sure the polarity matches the circuit.

[cteno4]

You can solder leads of like 30g wire and store the cap elsewhere. The cap will be a bit of a stay alive for a split second to help stop flicker. Long stay alive will require a big super cap though or move to constant lighting power supply.

 

jeff

[emkay_777]

Thanks, that looks doable for me, soldering-wise anyway.  However, my electronics knowledge is lacking.  Can you recommend an appropriate capacitor?  I just have a 22-014 standard Kato power pack

[emkay_777]

So I have a 220uF capacitor from a BCD project rated at 35V but it is quite large (relative to the train)

[cteno4]

Yeah those are the big cylinder electrolytics. Bulky and not so charge dense.

 

these tantaliums are much smaller and pack a whollop for the space. 16v would work and it lets you get a bit more charge for the buck and space, like the 220uf 16v is the same price and size as the 100uf 25v. Usually you want to have your voltage rating being 2x your Max used voltage for electrolytics. Tantalum you can get away with like 50% over your max voltage.

 

the higher the uF the longer it does the keep alive. So a 220uf will last 2.2x longer than a 100uf.

 

https://www.ebay.com/itm/1uF-4-7uF-10uF-22uF-47uF-100uF-220uF-330uF-6-3V-10V-16V-25V-Tantalum-Capacitors/233305751182?hash=item36521b3e8e:m:mpfg5Uk4O5CTLOIS_qBW7eg

 

cheers

 

jeff

[emkay_777]

So is it as simple as the following picture???  I would choose the 16V 220uF capacitor from the eBay link that Jeff sent.  Would I need a resistor so that it wouldn't 'flicker brighter'?  This is great - I'm all set to order some components and start experimenting, but like my electrolytic caps, they'll probably take months to get to me.  Oh, well.  Thanks for the input, guys, it's appreciated. 

 

Evan

[chadbag]

On those tantalum, make sure you have the polarity right.  Big bang otherwise.

 

[emkay_777]

Thanks for the heads up

[cteno4]

So looking at this carefully it’s odd as they put the resistor before the bridge rectifier so you can’t wire the cap in before the resistor and can only wire it to the le directly. I’m assuming the 6 lead chip is a bridge rectifier that just has 2 leads doubled up to do a half bridge if needed. Anyone know for sure what the chip is for sure? Resistor value is spot on for 12v max onnthe led so I assume it’s not some sort of current regulating chip but maybe it is as the current regulating Chips usually use a resistor to set the current out.

 

for the polarity you need to look at the back of the led to figure out the polarity of the led to match the cap to that. 
 

you can figure it out empirically by wiring one on a lead and then applying power to the board. If it works and doesn’t go pop! After a few minutes and dims slowly when power is removed then you got it right. If the cap goes pop or the led goes right off when you turn off the power then you got it wrong!

 

jeff

[emkay_777]

Are these the same, only different shapes?  I think they are, and they may be easier to solder to the light board, and hang directly beneath.

[chadbag]

Yes the ones with the legs should also work.  Again, just respect the polarity 🙂

 

And make sure you buy the size  (capacity) you mean to buy.

 

[cteno4]

Usually the legged ones are a bit bigger, the bricks have the best charge density and more available in the higher capacities.

 

easy to solder little wire leads onto the ends of the brick ones.

 

jeff

[chadbag]

yes the SMD ones tend to be higher density.  You notice the legged ones list 47uF as the largest while the SMD ones list 220uF