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Discussion Starter #1
Anyone have a schematic for a light circuit to keep lights from flickering, may be a capacitor.
 

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A rectifier and capacitor. GunRunnerJohn has a light circuit, I think. This is a basic one, but this assumes the LED has a built in resistor, and you want a capacitor in parallel with the LED. 35V 500-1000uf, minus towards the bottom. BTW, that will work with a lightbulb, too. It just may not be as bright with rectified voltage, but it won't flicker.

recitifer.jpg
 

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Tom gave a good summary. But what lights? A horde of incandescent passenger cars" A loco headlight? LED lighting?
 

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Can we assume you want to power each separately?

If you're rewiring one or more cars I recommend changing to LED, but it's not necessary and completely your choice.
 

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The first step in getting lights not to flicker is to give all the track, wheels and pickup rollers a good cleaning to get rid of any rust and dirt. Clean rust with a ScotchBrite pad, and finish off everything with a rag and Q tips soaked in Naphtha. That should minimize flickering.


Larry
 

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Here's a schematic of an LED module that will give you flicker-free lighting, DCS compatibility, and intensity adjustment.
I have been a little confused in the past about your regulator. Will this work with conventional (old school) equipment? I run exclusively pre-war and I am currently using an RW transformer. I have added lights to my 603s and 604 and I am in the process of "restoring" some 610s and a 612. I would like flicker free and a POT. Would your regulator be overkill for my needs?

TIA.
 

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If you're talking about a single LED application, you can do those with a simpler scheme. Basically a diode, capacitor, and the CL2 constant current regulator.

So, if you can be more specific about the application in detail, I can probably provide more focused answers.
 

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If you're talking about a single LED application, you can do those with a simpler scheme. Basically a diode, capacitor, and the CL2 constant current regulator.

So, if you can be more specific about the application in detail, I can probably provide more focused answers.
Just some pre war passenger cars (and maybe caboose) for interior LED lighting. LED strips, flicker free (capacitor), AC to DC (diode) and a potentiometer (POT) to adjust the light output level I am looking for. Pretty basic stuff. I use early post war transformers (RW-110 & KW) if that helps.

I like the idea of using PCBs to cut down on a wiring mess inside the cars.

TIA
 

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LED Lighting Regulator[/URL].

View attachment 522828
I don't want to hi-jack the thread if the answer is complicated.

I just received a new batch of 5 of the tiny MP series buck regulators. The trim pot in the first one I tested was "flaky" by my eye. I couldn't dial in any voltage between ~4 V and ~8 V. A big jump in the regulated voltage no matter how I fiddled with the pot. I used a 18 V DC supply for testing.

Do you find this style trim pot to be problematic?

Pot.png
 

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Just some pre war passenger cars (and maybe caboose) for interior LED lighting. LED strips, flicker free (capacitor), AC to DC (diode) and a potentiometer (POT) to adjust the light output level I am looking for. Pretty basic stuff. I use early post war transformers (RW-110 & KW) if that helps.

I like the idea of using PCBs to cut down on a wiring mess inside the cars.

TIA
Running conventional gets a bit tricky with the LED's. What I had one guy do is jumper out one of the LED's in each group of three to lower the voltage requirements of the string, then the conventional track voltage was enough to light the cars.

The problem is, you can either have a step-down or a step-up, having both is more expensive and also a larger footprint supply. In order for my board to light the "standard" 12V LED strips, you need around 9-10 VAC on the track. If you jumper out one LED, it's down to around 6-7 VAC on the track.
 

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I don't want to hi-jack the thread if the answer is complicated.

I just received a new batch of 5 of the tiny MP series buck regulators. The trim pot in the first one I tested was "flaky" by my eye. I couldn't dial in any voltage between ~4 V and ~8 V. A big jump in the regulated voltage no matter how I fiddled with the pot. I used a 18 V DC supply for testing.

Do you find this style trim pot to be problematic?

View attachment 522840
In general the pot has worked out fine. However, it's somewhat hard to adjust, so the next production run I may switch to a different style. I just have to find one small enough not to alter the footprint.
 

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Running conventional gets a bit tricky with the LED's. What I had one guy do is jumper out one of the LED's in each group of three to lower the voltage requirements of the string, then the conventional track voltage was enough to light the cars.

The problem is, you can either have a step-down or a step-up, having both is more expensive and also a larger footprint supply. In order for my board to light the "standard" 12V LED strips, you need around 9-10 VAC on the track. If you jumper out one LED, it's down to around 6-7 VAC on the track.
Thanks, John. That explanation helps.
 

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The problem is, you can either have a step-down or a step-up, having both is more expensive and also a larger footprint supply. In order for my board to light the "standard" 12V LED strips, you need around 9-10 VAC on the track. If you jumper out one LED, it's down to around 6-7 VAC on the track.
There are 5 V LED strips with all their LED/resistor pairs in parallel. I have some and tested them with the MP style buck regulators on a convectional transformer at minimum throttle.

You only need about 5 V AC on the track to light the strip as the the rectified voltage is ~ 7 V. For conventional operation the throttle jumps from 0 V to ~6 V AC on application of the throttle (w/ the exception of modern partial sine wave transformers) . And you can light as many LEDs as you like subject to the regulators' rating (and the size of the bypass capacitor at the lowest throttle settings).

With a buck regulator, the 5 V strips are more energy efficient then the 12 V strips. Less energy is dissipated in the 5 V resistors than in the 12 V LED resistors.

Think of it this way. Given the same LED and the same level of brightness yields an identical current draw. But the 5 V strips' lower value resistors will have lower voltage drops than the 12 V strips' resistors. Hence lower dissipated power in the resistor.

P = I squared X R
 

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Discussion Starter #17
experiment

I tried a 2200uf and a wave bridge with incandescent bulb. Still no good. Running conventional ac, if I use LEDs I need regulation right? Not sure how that will help me. The cap is doing all of the storage.
 

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An LED lighting configuration can extend the "on time" by an order of magnitude to avoid flicker.

Consider a single incandescent bulb using 250 ma at 12 V. That's 3 W. Compare that to, say, 4 LEDs using 10 ma (40 ma total). At 5 V, that's 0.2 W. That's a 15 fold savings on the cap's reserve energy.

Plus, the capacitor is charged up to track voltage. With the track power at 12 V AC, a bridge will charge an unloaded capacitor up to ~ 17V DC. If using a buck regulator with 5 V LED strips, that extra voltage differential is energy in the cap to extend the holdover time (i.e., the regulator can provide a steady output while the cap's voltage decreases as it discharges after the power loss).

The video: ~12 V AC "track power" via conventional Marx transformer. A Buck regulator with bridge and on board 1000 uf cap. A strip of four 3528 LEDs in warm white (see the chart, below). I had these dialed down to ~10 ma each, 40 a total load at ~3.25 V DC to the strip.



LED Comparisons.png
 

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PHP:
In general the pot has worked out fine. However, it's somewhat hard to adjust, so the next production run I may switch to a different style. I just have to find one small enough not to alter the footprint.
There's these single turn, 20% tolerance styles in standard resistances (5K ohms linked) available in single quantities from Digikey.

The problem with the style on the existing boards I received is they're all over 20 % tolerance. Bourns makes that style but they're all out of stock at digikey in single quantities.

And the linked Bourns are 4 to 5 times the price of those cheap trim pots..


A Bourns at 20%tolerance with a footprint of 2.8 mm x 2.5 mm.

https://www.digikey.com/product-detail/en/bourns-inc/3312J-1-502E/3312J-1-502ECT-ND/1880826

And another Bourns with a slightly larger footprint at 3.5 mm x 3.2 mm.

https://www.digikey.com/product-detail/en/bourns-inc/3313J-1-502E/3313J-502ECT-ND/612900
 

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I tried a 2200uf and a wave bridge with incandescent bulb. Still no good. Running conventional ac, if I use LEDs I need regulation right? Not sure how that will help me. The cap is doing all of the storage.
Can you post a diagram of what you did? 2200uf is big but should still work. What kind of bulb is it... seems it would be drawing a lot of current to drain that cap.

LEDs will require a resistor if they don't have it built in, but you could also use a regulator (LED driver thingy) like the one John mentioned.
 
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