Large Scale Central

Car lamp capacitors

Electronics Power and Sound
#1

My passenger coaches and cabooses have LGB 68333 24v bulbs in them wired up to track power through LGB ball bearing wheels. But they flicker quite badly. I would like to put capacitors in each car to stop this but all the retail options I have seen either come with the lamps (which I already have), say they are only for Analogue DC, and cost a lot of money. I am sure I can buy the capacitors and wire them into the lamp circuit for a few bucks each but I have a couple of questions.

What size cap(s) do I need? The coaches each have two of the 68333 24v non led bulbs in them hooked one after the other. Would a 1000uf 35vdc electrolytic cap suffice or are they too small? I can 20 of these for 8 bucks on Amazon. I think I only need a few seconds of charge.

The cabooses each have two of the 24v non led bulbs and two of the lantern lamps. I am not certain the voltage of the lantern lamps. I am guessing 18v. For these cars, should I run separate capacitors, one for the overhead lamps and the lanterns?

I am running DCC on a 10A Brutus for power. I have read AC volts are calculated differently from DC volts in regards to how much current they can handle but not sure how to calculate it.

Do I just solder the cap in series to the positive wire between the bearing pickup and the lamps?

Do I need anything else such as resistors or diodes?

#2

WELCOME DERAILED !

#3

Thank you.

#4

When running with DCC and lots of capacitors, you can have a current trip of your system due to the surge of power when first turning it on to charge all the capacitors.

It is better to use leds (much less current) and wire them in series as 6 of the 20ma 3 volt leds in series will be 18 volts and the cl2-n3 device will limit the current to 20 ma. Of course you will need a full wave bridge rectifier to get dc for the leds and cl2-n3. Also due to the low current better time with a capacitor for power storage.

So, 6 leds at 20ma vs your 2 24 volt bulbs at 33ma each for 66ma (or double that for 4 24 volt bulbs).

Also note that users that only get power from one axle on a car must remember that not all 4 wheels of a car touch the rails!! Sometimes the wheel not touching is the one for power pickup (uneven track, plastic frogs). All my cars have 2 sets of track power pickup and I tie 2 cars together to insure power is picked up.

#5

DCC polarity switches back and forth, sort-of like AC. So you would need a rectifier, or some diodes, so you don’t pop the capacitors. They don’t like having the wrong polarity applied to them.

35 volt capacitors should be fine, assuming you are putting 24 volts (or less) on the rails.

As for capacitance rating, You may have to experiment to see what works. The time they will sustain the lights depends on the capacitance rating and how much power the lamps draw.

I would not think you would have to build 2 separate circuits for the different lights, if they are all drawing power from the rails now.

#6

Apparently no so simple after all. I hate to swap out all those 68333 lamp boards. The bulbs have those two prongs. Can I just stick in 5V 5mm clear LED bulbs into the sockets? Along with the modified circuit of course.

On another note, I have a bunch of L7805s. Could I use those instead of the BR?

Many of my cars only have one BB axle. Those things are expensive. I was hoping I could spend a couple of dollars on caps per car rather than another $20+.

#7

You can use the LM7805 to feed leds with a dropping resistor. And these regulators are available in 100ma versions which are very small and can feed up to 5 of the 20ma leds wired in parallel.

Better yet is to get 12 volt leds that can just have a 12 volt source to feed them directly, no regulators, no resistors, just a polarity issue.

#8

Or purchase the cheap Chinese regulator boards, dial the voltage to 3.6 volts and run the leds directly from the output.

$1.67 each… track pickups >> full wave bridge rectifier >> small electrolytic filter cap >> converter set to 3.6 volts (just slightly less for safety) >> directly to as many leds in parallel as you want… no heat like the series pass regulator, small, efficient, works on any track voltage.

https://www.ebay.com/itm/Boost-Buck-DC-adjustable-step-up-down-Converter-XL6009-Module-Voltage-NEW/191673952440?epid=594020377&hash=item2ca0a868b8:g:0CAAAOSwLVZVs4ch

Greg

#9

Thank you. I do wonder when they would get here from China now? :frowning:

what size bridge rectifier would I need?

Is there a way to determine how long a cap will provide power? For example 1000uf cap / 2x20ma bulbs = 25 seconds etc?

Sorry. I do not have an electronics background. All I know I have learned from trying to keep my pinball machines working. (my other hobby) But those are relatively easy as the parts are already there. Just need to find the bad part and replace it.

#10

Many are in stock in the USA, check details of delivery dates before ordering.

50v bridge at whatever amperage you need. figure out how many LEDs you are using, calculate .02 amps per LED, multiply by that and you have amperage… most likely 1 or 1.5 amp is fine…

35v electrolytic, maybe 220 microfarad, not trying to do energy storage, just give relatively clean voltage to the LEDs

If you still get flicker, then you can put bigger cap on the LED side, but then you can use 5v super caps and will never flicker…

Greg

#11

For passenger coaches, one thing a guy in my club has done is use MU cables to all his passenger cars so all of them are drawing from every axle to share the pickup. Hasn’t had a flicker in his cars since.

#12

Bill Sakalaucks said:

For passenger coaches, one thing a guy in my club has done is use MU cables to all his passenger cars so all of them are drawing from every axle to share the pickup. Hasn’t had a flicker in his cars since.

This can create problems at “blocks.”

#13

If the blocks are longer than all the cars, no problem, but if a second train enters the block while first train is leaving the block, all bets are off!!

If someone does not understand this then they should avoid blocks or just run single trains thru a block.

Note any train with metal wheels can cause block shorts.

#14

ITS ALIVE, ALIVE! Works like a charm, no flicker at all through my switches.

Thank you, again.

Now, to figure out where the hide this big circuit board in my coaches. I found a spot in the combine test car. But the bathroom and stove are in the way in the coaches.

I ended up using a 470uf 35v cap since I had one on hand and the ones I ordered are delayed for a few weeks due to shipping issues.

#15

What did you buy/use? You mentioned the cap, but what “big circuit board” is this?

Greg

#16

Just don’t understand the compulsion to light using track power, with a $.99 battery holder a $1.00 switch and $1.00 piece of styrene 2 dime 10mm LED’s you can battery power it and two years later when you decide to switch from track power to onboard battery your cars will still light

#17

That step up/step down converter. Its about 1"x2"

#18

I seriously doubt I will switch to battery power any time soon.

#19

Bill, I cannot imagine why anyone would use battery power and give up smoke units in the loco, or not be able to have fully lighted cars, or would want to change batteries…

See, I can make the same point as you, but in reverse easily.

It all depends on what you want… if you just want a couple of lights that is cool, but if you want fully lighted cars, or smoke units, or trains that are ready to run always, or have cars with incandescent bulbs (I am NOT tearing open 10 streamline cars to change to LEDs), then track power makes sense.

The point is people have different priorities, and different needs, so you needs being different does not mean everyone else has the same priorities as you.

Greg

p.s. after 2 years most batteries leak and corrode the battery box…

#20

I got it to fit, tucked up under the roof above the bathroom. Didn’t think it would but there was just enough space without using standoffs and by moving the cap and Bridge a bit to clear the stove pipe. Will that unit get hot enough to melt the plastic? Thanks again for the info.

I’m a “Roundy Rounder.” I like to run my trains on auto for hours while I sit by the fire pit, drinking and smoking cigars. Once running, I don’t mess with them except to add more smoke fluid, or fix the very occasional derail. I don’t want to worry about batteries running out of juice.

I know the new tech is wayyy better than my old RC Car batteries, but I hated dealing with batteries back when I was racing the cars. I don’t want to deal with that again, at all.

I also don’t see the point of using alkaline batteries for car lamps when I have a perfectly good power source underfoot. I like to tinker so modifying the lamp circuit once is not a negative, especially during this COVID lockdown.

As far as cleaning, I have a track cleaning loco I use once a year. My Bobber has the LGB cleaning pads under it and that seems to be enough.

Dan