I have an HO DC layout and I have installed a led light strip with 7 small leds in my passenger car. I am using wheel axil pickup and a 25volt, 470uf capacitor to stop flickering. Unfortunately the car flickers as it runs my layout. Can anyone tell me how to stop the flickering problem. There appears to be good pickup at the axil.
Thank you
Brian
Dirty wheels, dirty track, or dirty pickup wipers can all cause flickering. 470uf is not enough to stop the flickering from the aforementioned causes.
Brian,
Hmmm, 470 uf has always been more than enough to kill flicker for me.
Those caps have polarity, so you may want to check that. The cap should be placed across the postive and negative leads.
Do you think I will need a higher capacitence capacitor or maybe use two 470ufs because I am using a led strip with 7 small leds? When I turn the power off the leds fade off withing a second.
Brian
Which way are you going?
Do you have a bridge rectifyer in your circuit?
The caps have a + side and a - side, and if you reverse directions without keeping the polarity of your circuit correct you are causing problems.
The AC side of the bridge rectifyer goes to the tracks, the + and - side to your capacitor and to the lighting circuit.
ROAR
Is the flickering faster than that? It sounds like you have a large enough capacitor. Carrying it over as long as a second should be plenty.
How many wheels are you using for pickup?
If your capacitor is really holding for a second and the flickering is faster than a second, then you probably have a loose wire between the capacitor and the LEDs.
Nah, something’s not right with the circuit. I am assuming these are LED strip light sections, so require 12 volt input? That’s what I use. You should get considerably longer than that for run time.
Here’s a link to a comment with a cruddy diagram (sorry) of the circuit I use. Basically, you want the cap after everything else, soldered across the + and - leads to the LEDs, with the cap leads connected in proper polarity.
470 uF isn’t big enough to do anything useful. I used 0.47 Farads, like a 1000 times more. That cap would keep the lights burning for 20 seconds after track power was removed. The supercaps are fussy and require quite a bit of electronics to make them happy. You want a bridge rectifier to feed 'em a constant polarity, followed by a 5 volt regulator to keep from zapping them. Followed by a 1.5 volt regulator if you light with 1.5 volt bulbs, or a 470 ohm resistor in series with LEDs. All this will fit inside an HO caboose, I did one, fun project, but so much trouble that I won’t do another one.
Other than that, pay close attention to clean wheels, clean track, solid wiring, plenty of ballast.
I am using a bridge rectifier and the polarity is correct on my capacitor. I am using a Huff Tronics led strip.
Brian
If you guys re-read the first post, he’s using DC on his layout.
If your LEDs are resistored for 12 volts, you would have to be running your train at or near 12 volts for the capacitors to gain enough charge.
Stay alive capacitors will not function well, if at all on DC.
Mark.
Yes I am running DC and they are Hufing-Tronics led strips with a bridge and a variable resistor to adjust the output brightness. Is there a differant size or type of capacitor or something else completely different that will work better?
Brian
Not really answering you, but rather throwing fuel on the fire, for I have not tried it yet…
I want to take five 1 Farad supercaps rated for 2.5 volts each and wire them in series so what I will have is a single 1 Farad assembly that will withstand 10.2 volts which is my standard track power. Naturally there must be a full wave restifier between the track and the hotel circuit.
I have high hopes for this but have not tried it yet. I want my lights to remain lit while the train is stopped in the station, so about 20 to 50 seconds.
ROAR
I’ve built numerous boards using this article for my cabeese …
http://members.optusnet.com.au/nswmn/flicker_free_JB.htm
It will keep the LEDs lit for well over one minute. I run DCC, but it states the circuit will also work on DC. The Supercap is the key. The low voltage rating is also the key as it can be charged using lower voltages. The 1000 ohm resistor in the circuit prevents the capacitor from seeing more than its rated voltage.
This circuit DOES work.
Mark.
Sorry 'bout that. No, my circuit doesn’t work on DC.
I would not do it that way. Capacitors in series combine the same way as resistors in parallel. i.e. 1/C1 + 1/C2 + … = 1/Ctotal. So four 1 farad capacitors in series are only equivilent to a 0.25 Farad cap. In short, you would be paying for four Farads worth of capacitor and only obtaining 1/4 Farad in service.
Was it me, I’d buy a single 5 volt super cap. Protect it from your 10.5 volt track power with a solid state 5 volt regulator. The regulators are simple to use, they are three terminal devices, gozinta, gozouta, and ground. Apply your unregulated juice to gozinta, and you get a steady 5 volts from gozouta. Easy. Biggest 5 volt supercap available used to be 0.47 Farads.
Light the car with LED’s. Use a 470 ohm resistor in series with each LED. 5 volts/470 ohms = 10.6 mA, plenty bright enough. 0.47 Farad times 470 ohms yields a time constant of 220 seconds. Which means the voltage on the capacitor will be 63% of 5 volts after a 220 second discharge. That little dimming is inperceptable to the eye. One LED doesn’t throw enough light? Put in more. Each LED and its current limiting resistor will shorten the time constant. But I could put in 10 LEDs (gross overkill) and t
[quote user=“dstarr”]
BroadwayLion
Not really answering you, but rather throwing fuel on the fire, for I have not tried it yet…
I want to take five 1 Farad supercaps rated for 2.5 volts each and wire them in series so what I will have is a single 1 Farad assembly that will withstand 10.2 volts which is my standard track power. Naturally there must be a full wave restifier between the track and the hotel circuit.
I have high hopes for this but have not tried it yet. I want my lights to remain lit while the train is stopped in the station, so about 20 to 50 seconds.
ROAR
I would not do it that way. Capacitors in series combine the same way as resistors in parallel. i.e. 1/C1 + 1/C2 + … = 1/Ctotal. So four 1 farad capacitors in series are only equivilent to a 0.25 Farad cap. In short, you would be paying for four Farads worth of capacitor and only obtaining 1/4 Farad in service.
Was it me, I’d buy a single 5 volt super cap. Protect it from your 10.5 volt track power with a solid state 5 volt regulator. The regulators are simple to use, they are three terminal devices, gozinta, gozouta, and ground. Apply your unregulated juice to gozinta, and you get a steady 5 volts from gozouta. Easy. Biggest 5 volt supercap available used to be 0.47 Farads.
Light the car with LED’s. Use a 470 ohm resistor in series with each LED. 5 volts/470 ohms = 10.6 mA, plenty bright enough. 0.47 Farad times 470 ohms yields a time constant of 220 seconds. Which means the voltage on the capacitor will be 63% of 5 volts after a 220 second discharge. That little dimmin
I like the idea of the supercaps for longer stay on time and reduced flickering. This is what I am using on my DC layout with wheel axil pickup.
pic of Hufing-Tronic LED strip I am using - file://localhost/Users/brianulrich/Desktop/IMG_0910.jpg
pic showing bridge and variable resistor - file://localhost/Users/brianulrich/Desktop/IMG_0911.jpg
pic showing 25v, 470uf - file://localhost/Users/brianulrich/Desktop/IMG_0912.jpg
Where would I hook up the supercap and what else will I need and where should I install everything?
Thank you
Brian
I already posted the link to the diagram, didn’t you look at it either ?
Mark.
I did look at your posting, thank you for it, but will a .047 farad, 5.5volt supercap stay lite longer then my 25v, 470uf that is pictured below. Can I just replace my 25v, 470uf with a higher capacitenance cap at a lower voltage and still light my 12v DC system LEDs without and additional voltage regulator or …? My setup now fades to off within 1 sec.
my Hufing Tronic LED strip file://localhost/Users/brianulrich/Desktop/IMG_0910.jpg
my bridge and brightness control file://localhost/Users/brianulrich/Desktop/IMG_0911.jpg
my 25v, 470uf cap installation file://localhost/Users/brianulrich/Desktop/IMG_0912.jpg
Thanks
Brian
Still don’t know what’s in your links - they are just linking a picture that appears to be located on your desktop - you’d be the only one who could see them.
A 0.047 farad capacitor is equivalent to 47,000uf, so it has 100 times the capacity of what you currently have. You need to remember, the supply voltage to the capacitor cannot exceed the voltage rating of the capacitor itself. That is the reason for the 1000 ohm resistor inline before the 5.5 volt supercap - it prevents it from getting more than the rated voltage.
The resistors between the supercap and the LEDs not only give the LEDs the current they required, but also acts to slow te discharge rate from the supercap keeping the LED on longer.
You can use any value supercap you want up to one or two farads or more, as long as it is rated for 5.5 volts. But - it will also take longer to initially attain a full charge. You will also need to average 3 to 5 volts on the rails for the cap to charge, but once fully charged, it will maintain and replenish as required.
Mark.