Kato platform lighting

[kvp]

The same, all the resistors would blow around the same time, the same way. Each 3 led group is independent from the others.

[inobu]

:)

[Khaul]

Well, yes, the resistors in all the three separate LED sections got fried. Even the one in the station entrance with plenty of air around it burned out. 

 

Now, I have been reading a little about unregulated power supplies like mine. There is something interesting I found, see below. Maybe because the load of my power supply was so little the voltage was for starters higher than 12V on average. Maybe a voltage surge on top of that caused the problem. So there may be a point with what Inbou says, and that would also explain why most people don't have problems when they supply long strings of LEDs with unregulated sources. I think what the manufacturers have in mind for LED strips is that users will cut just a few sections to adjust the length, but not connect as little as 2 or 3 sections like I did.

 

In any case, regulated power supply should make things work properly. I believe.

 

The first important concept to understand about unregulated DC voltage output power adapters is that they are designed and rated to produce a particular voltage at a particular maximum output load current. The output voltage of an unregulated power adapter will decrease as the current provided by the adapter output to the load increases. The power adapter selected should be matched as closely as possible to the voltage and current power requirements of the load.

Example: A given unregulated power adapter has an output rating of 9 volts DC at 500ma (500 milliamps = 0.5 Amps).
This rating means that the unregulated voltage output of the power adapter will be 9 volts DC when it is under the full rated load of 500ma. Many people are surprised when they plug an unregulated power adapter into a wall outlet and measure the DC output voltage of the power adapter with a volt meter. While the adapter is providing no power to a load device, the measured output voltage is several volts higher than the rated voltage of the power adapter. Often, people jump to the conclusion that something is wrong with the power adapter, while the simple explanation is that the power adapter has no voltage regulator, and this is normal. But if the same unregulated power adapter is connected to a load which draws 500ma of current, the measured output voltage of the power adapter would drop to the rated 9 volt DC output level as it should.

[cteno4]

Now that you mention this I do remeber reading this quite a while back about unregulated power supplies. Even regulated power supplies like old pic power supplies many use require a small power draw to work. Folks have had that same thing if it not working when powering s few leds, but add a small 12v bulb across the power supply then everything is happy.

 

This sounds like the likely scenario, low draw so higher voltage and a spike or surge and pop goes the resistors.

 

They just don't design these for a lot of overvoltage situations. Guess they could use 0.25w resistors but probably more expensive...

 

I may try blowing some up on the bench and see what voltage pops them and put flammable material on top of the resistors to see if they can ignite anything.

 

I bought a cheapo used little digital oscilloscope a few months back just to look at things like this, this is a good excuse to test a variety of power supplies I have laying around here. I do remeber testing just meter voltage on a variety of 5v USB type power supplies I had around here a few years ago and found them to be very consistent as I expected they may be a bit better regulated than many of the other voltage units out there. But can only tell how well they are on spiking or leaking ac with a scope.

 

Cheers

 

Jeff

[Khaul]

So I did not give up on platform lights after all. I have done some improvements to the basic design:

 

-most importantly the lights will work at 9v

-lights are now mounted on an aluminium strip

-I have added JST connectors so maintenance becomes easier

-I am going to leave the LEDs uncovered, at least initially. They are less bright at 9v and I have applied weathering to the platform to avoid too much reflection. The little station building looks a bit dim at 9v so I will also add more lights there.

-as you can see in one of the pictures below I have been experimenting with soldering glue. It's working. Let's see for how long.

 

 

Edited November 17, 2017 by Khaul

[cteno4]

khaul,

 

nice! yes lowering the voltage on those will help make them not be blindingly bright and be better on the components!

 

another option for mini connectors is to use 40pin PC connector strips and cut them off in pairs of pins and sockets and just solder to them and bit of heat shrink on them.

 

works out really inexpensive and about as small as you can get for connectors w/o going more exotic (like 1mm pitch pin connectors)

 

https://www.ebay.com/itm/3Pcs-40Pin-2-54mm-Single-Row-Round-Female-Pin-Header-Socket-gold-plated-hc-/332162995178?hash=item4d567513ea:g:~xwAAOxyhS9TfWBY

 

https://www.ebay.com/itm/2PCS-Single-Row-40Pin-2-54mm-Round-Male-Pin-Header-gold-plated-machined-CA-/142204120810?hash=item211c06aeea:g:enMAAOSw5cNYR8rs

 

cheers

 

jeff

[Khaul]

Hi Jeff,

 

I will definitely consider those in my next project/upgrade. I am slowly overcoming my aversion to the soldering iron.

 

Pablo

[cteno4]

Pablo,

 

no worries soldering is just practice, practice, practice. It gets easier and more comfortable the more you do. Worth just doing a load of practice solders to get more comfortable and also check out some of the YouTube videos as they can show a lot on technique.

 

good luck and don't let it scare you!

 

cheers,

 

jeff

[Spaceman Spiff]

Led lights purchased from EBay. About $1 each.

[Yavianice]

21 minutes ago, Spaceman Spiff said:

Led lights purchased from EBay. About $1 each.

 

Looks really cool Spaceman! I should really get to buying some LEDs for my station sometime...

[gavino200]

I finally got back to the trains this weekend, after a long hiatus. Did a bit of work on my platform lighting project. I'm fairly pleased but there are a few issues. 

 

The covered platforms are way too bright. All  the lamp post pots are turned fully up. All the covered platform pots are turned fully down. I may remove half of the LEDs (every second LED). And I may also change out the potentiometers for ones with a higher resistance.

 

 

This is my growing mess of wires. 

 

 

I'm hoping to get the station building lit next weekend.

[cteno4]

Gavin,

 

hey good to have you back! 

 

Yep, I've always found I have to turn leds down more than I expect in many lighting situations! 

 

Jeff

[gavino200]

Finally got the project finished. I haven't finished "tuning" it yet. ie using the pots to dim the lights down to realistic levels.

 

For control, I just went with three switches on the layout front panel. Platform 1, Platform 2, and Station.

 

I did the wiring in a modular fashion, so I can remove any one part without disturbing the rest. Good thing too, as I had to remove the main station house for some alterations before I was finished.

 

FYI, I used two different types of pots shown below. The first is simple to adjust even when you aren't looking at it. The second is very hard to adjust even when you're looking straight at it. The screw is tiny and shallow, and it takes about 35 turns to adjust it fully up or down. I might try to "mod" a screw driver, so I can adjust without looking. 

 

 

 

 

 

 

 

 

 

Edited November 16, 2017 by gavino200

[gavino200]

 

 

 

 

Edited November 16, 2017 by gavino200

[cteno4]

Yep the screw type give you very fine control, but lots o turns needed! The single turn guy's don't hold up to a lot of tuning, usually rated for just a few dozen swipes before they start to loose tolerances.

 

helpful little tool for this and other things like track screwing.

 

http://smile.amazon.com/General-Tools-500-Precision-Screwdriver/dp/B002XZLTQO/ref=sr_1_9?s=power-hand-tools&ie=UTF8&qid=1510804594&sr=1-9&keywords=power+screwdriver

 

and if you want a wide range of tips for it

 

https://smile.amazon.com/gp/product/B00FHRYE0S/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

cheers

 

jeff

Edited November 16, 2017 by cteno4

[gavino200]

10 minutes ago, cteno4 said:

Yep the screw type give you very fine control, but lots o turns needed! The single turn guy's don't hold up to a lot of tuning, usually rated for just a few dozen swipes before they start to loose tolerances.

 

helpful little tool for this and other things like track screwing.

 

http://smile.amazon.com/General-Tools-500-Precision-Screwdriver/dp/B002XZLTQO/ref=sr_1_9?s=power-hand-tools&ie=UTF8&qid=1510804594&sr=1-9&keywords=power+screwdriver

 

and if you want a wide range of tips for it

 

https://smile.amazon.com/gp/product/B00FHRYE0S/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

cheers

 

jeff

 

Thanks. Those screwdrivers do seem cool. But the main problem is how easily the screwdriver slips out of the screw groove. I'm thinking of hot gluing a matchstick or something onto the screw so I could turn it by feel while looking at the light that I'm trying to adjust. 

 

Once it's set, I shouldn't ever need to touch it again.

Edited November 16, 2017 by gavino200

[cteno4]

Hunk of like 060 strip styrene stock, make it a bit wider and just file in a little notch to dovetail into the slotted stem and glue in place! 

 

Jeff

[gavino200]

4 minutes ago, cteno4 said:

Hunk of like 060 strip styrene stock, make it a bit wider and just file in a little notch to dovetail into the slotted stem and glue in place! 

 

Jeff

 

Hmmm. Perhaps I could melt some of that and emboss it onto a spare potentiometer to make a custom female impression of the screw. Then use it as a screwdriver.

[gavino200]

Redoing the wiring for the Kato station. I extended the station by one platform length a while ago and never got around to adding lights to the new platforms sections. I decided to redo all the wiring as it's always been over-complicated and difficult to adjust.

 

This was my first LED project and I was a bit afraid of blowing the LEDs. I've used LED chains for all the platforms. This is the product. https://www.aliexpress.com/item/DD85W0850-1-Strip-50-LED-Pre-soldered-micro-Copper-Wired-WHITE-SMD-LED-0805/32801413908.html?spm=a2g0s.9042311.0.0.68b34c4dzquzWK

 

But I've modified it a bit. I've shortened each by about a third and then removed every other LED. So I didn't know how to calculate what a safe limiting resistor would be. So I just used the recommended resistor and made a circuit for each LED strip. That turned into a huge mess of wiring and made it very difficult to tune. Using those 50 turn potentiometers under the table without looking is extremely hard. 

 

I have two platforms. Platform 1 and platform 2. And a station.

Each platform is composed of four Kato covered platforms and two Kato end sections.

There are 3 control switches. Platform 1, platform 2, and station.

 

I'm planning on wiring the LED strips on all four Kato covered platform sections for each platform. ie. 8 LED strips for platform 1, and 8 LED strips for Platform 2. 

 

So here's my math.

using this LED calculator.

http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator

 

Each LED strip has the following requirements from the Ali Express page

Current 15mA

Voltage 3V

The factory stock LED strip has 50 LEDs in parallel.

I have adjusted this to 50 LEDs in parallel

(one platform is made from using two separately wired scraps - so approx a 10 and a 6 chain. 

 

I think fewer LEDs in parallel means more resistance, lest current.

 

Not sure if I can get away with using the factory numbers for the LED strips or if I need to recalculate. 

 

I don't mind going well over on the resistor. I'll be turning it down A LOT anyway to adjust the light. I'm only worried about to little resistance. ie burning the LEDs when the potentiometer is a minimum.

 

Using 

15mA, 3V, a supply voltage of 5V, and a number of 8 LEDs in parallel,. the calculator tells me to use an 18 Ohm resistor. 

That seems VERY low. 

I was planning to start with something much higher. Like 1000 Ohms. Any suggestions or ideas? @Kiha66, @cteno4, @kvp??

 

http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator

 

 

 

Edited December 25, 2018 by gavino200

[cteno4]

Gavin,

 

running multiple leds from a single resistor in parallel like this is a risk. If one of the leds is a tad different it will start drawing more current than the others and will start to heat up making it draw more current, while the rest will draw less current (due to more being drawn by one) and get cooler making them draw less current and thus more current into the hot one and vicious circle until the hot one finally blows, then more current is pumped thru the rest (due to the blown one no longer drawing current) and the whole thing can repeat faster with the extra current.

 

where it can work w.o any issues is if your overall current you are pumping in is at the max current of a single led. So 4 leds in parallel with a single resistor for current drop to 20ma would be ok as even if one draws slightly more than others you won’t have a runaway situation and never fry a led. So really each led will be running at 5ma. This actually is pretty good as I find leds in lighting situations usually are best lower like this. But 

 

in practice leds are used in parallel like this to be cheap and avoid adding a resistor for each, but it can fail on you and last thing you want in an install like this and have to replace later. Most of these parallel smd led parallel strings I’ve seen are run by 3v batteries where there is little or no voltage drop needed and the internal resistance of the battery helps limit the current. The fairy light string of 20 I tore open just used a 3v 2032 battery and no resistor.

 

basically to calculate the resistor needed you would multiply the amperage for each led (at what you want to run it at) by the number of leds, so here 10x0.015=0.15amps. So if the forward voltage of the leds is 3v and say you are using 5v power supply you would have a 2v drop to do, so R=V/I or R=2/0.15=13.33ohm resistor. But you will need a beffier resistor that you need for dropping for a single led. Here P=IE or P=0.15x2=0.3w, so you would need to use a 1/2watt resistor.

 

I would recommend trying modules of like 4 or 5 leds in parallel and run the whole line at 20ma total, so if using a 5v power supply it would only need 1/4 or 1/8 watt resistor or pot at 225ohms. You can use an smd resistor on the low amp situation that are the size of the leds. Then wire these small modules to a 5v power bus. Experiment and see what gives you the best lighting.

 

Jeff

[gavino200]

1 hour ago, cteno4 said:

 

 

basically to calculate the resistor needed you would multiply the amperage for each led (at what you want to run it at) by the number of leds, so here 10x0.015=0.15amps. So if the forward voltage of the leds is 3v and say you are using 5v power supply you would have a 2v drop to do, so R=V/I or R=2/0.15=13.33ohm resistor. But you will need a beffier resistor that you need for dropping for a single led. Here P=IE or P=0.15x2=0.3w, so you would need to use a 1/2watt resistor.

 

I would recommend trying modules of like 4 or 5 leds in parallel and run the whole line at 20ma total, so if using a 5v power supply it would only need 1/4 or 1/8 watt resistor or pot at 225ohms. You can use an smd resistor on the low amp situation that are the size of the leds. Then wire these small modules to a 5v power bus. Experiment and see what gives you the best lighting.

 

Jeff

 

Thanks. I think I have a rough plan in mind. 

 

The good thing is that even with protecting resistors the LED are always mega bright. The amount of extra resistance that needs to be added to bring the brightness down is orders of magnitude greater than the protective resistance. So I can use protective resistors that are excessive an safe. 

 

I want to avoid having a mess of wiring. I want to be able to remove one single unit of the station (ie a single platform) for work without removing the rest, if needed. And I want to have a minimal number of pots to adjust to get the light level right.

 

So negative wires will all run directly to the switchboard. The original one will be fine but this time I'll label or number the wire positions to make it easier to remove a component selectively.

 

The positive wires will go through two boards under the table. The first will be simply a protective resistor board. wire screw terminals on each side connected through a resistor. 

A resistor for each covered platform, plus one for each pair of end platforms. That makes 10 resistors. Also I'll keep the station broken into three or four segments, each with their own resistor. I'm planning on using 1K ohm resistors and will adjust down if needed. I'd bet not needed. 

 

Then the out put wires will pass to a second smaller board. All station wires will converge at the input and go through a single brightness contorl potentiometer. The four covered Kato segment for each platform will converge to go through one pot. (one for each platform). And the two end platform pairs (one for each platform) will get their own platform. So total of two pots. That makes five pots in total. Relatively easy to adjust. 

 

The reason I'm keeping the end platforms and covered platforms separate is that I'm expecting that the current needed for optimal light will be very different. I may do a trial of joining them, but I'm expecting to keep them separate. 

 

Then all positve wires converge to complete the circuit.

 

 

Edit: I may go back and replace all these LED chains with LED strips hidden under the canopies, at some stage. I liked the idea of a string of lights small enough to fit on the narrow hanging ledge of the platform roof. And I think it looks ok, I don't hate it. But I think that the hidden lights just look a bit better. You appreciate the illumination without having your attention drawn to the lights themselves, which are not perfect.

 

Edited December 25, 2018 by gavino200

[gavino200]

I used three small boards. I had to split the station lighting into two circuits are there are two very different LED types inside. So six circuits. I used very safe resistors and worked my way down. The boards are designed to make resistor switching easy. I still need to do some adjusting so that the potentiometer adjusts through the most useful range of brightness change. These giant pots should make adjustment easy. 

 

I might clear coat the platform roofs to get rid of the plastic look, and do a bit of detailing before putting the station back on the board.

 

[gavino200]

I'm happy now with the wiring setup. It was a whole lot easier to troubleshoot on the kitchen table than under the layout. I'm keeping all the wires very long so I won't have to do any soldering or crimping under the table. It's also modular, so I can remove each of the pieces one at a time.

 

But I'm going to move the covered platform LEDs to a position under the canopy where they won't be seen directly. I thought this approach would look good, but it doesn't. The LEDs distract too much from the station, rather than enhancing it. The eye sees the lights, and you have to willfully focus in again to see the station. If you look at the station from a steep angle (ie, above) you can see the illumination effect without being able to see the LEDs. The effect is opposite. You see the station, but with enhancement. Much more 'realism'. 

 

I'll try to do a bit of detailing too while I'm at it. One platform at a time. Looks like we'll have a kitchen table station for a little while longer!

[gavino200]

First experiment with hidden platform LEDs. Definitely an improvement. This is just connected through a resistor to a 9V battery so I can't adjust the brightness. It's 3 LEDs in parallel on two strips of magnet wire.

 

I may experiment using 5 LEDs turned down less brightly for a more even platform illumination. Any opinions?

 

[cteno4]

yeah the more, tuned down leds the better as the better the coverage and less hot and dark areas. do you have some white paper behind the leds to help diffusion?

 

the three in parallel in sets you just wire to a master power feed up to the roof should be easy. each can have a small resistor at the end of the chain to attach to the main feed then throttle that back with your main pot. i think if you used static resistors on each group of three to drop them to 5ma per led from 5v, then one of the .5w trimmer pots should be fine to trim down there like 4 sets of three as long as you are just trimming a bit more off. these could mount in the platform base and just one per platform and adjust thru a hole there and then just plug into a 5v power bus. or wire back to a central panel.

 

wrapping wire works well for this stuff, way easier to solder than magnet wire and sturdier. its about the size of a 1" electrical conduit.

 

another idea is to use diffusers over the leds and run them a bit brighter (inobu where are U?!), but getting a good diffusion material can be a bit of work and it tends to just make your transition from brighter and dimmer areas more gentle.

 

also need to test under the lighting you want when you are doing lighting. some dont like total dark in the room, so some dim lighting. lots of lighting happens during the day as well in many places but at scale you have to exaggerate it there to make a daylight lighting effect thats blasting at an evening/night lighting. 

 

jeff