Lighting questions

Discussion in 'How this forum works - FAQ' started by Setaf, Mar 3, 2022.

  1. Setaf

    Setaf Full Member

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    Not sure which forum to ask this under so pardon if I made a mistake. I'm in the process of figuring out how I want to light my buildings and have decided on LED light strips, 12v, cutting them down to 3 LED strips. I also am looking at a few white individual diodes but am wondering what people on here use most of 5mm or 3mm? I'm assuming 12v there also. Does anyone use anything smaller for HO? And if you use 5mm and 3mm, what applications do you use them for? Last question, does anyone or has anyone used copper foil tape? I saw this used in a video recently and it seemed like a handy thing to have available.
     
  2. gormo

    gormo Staff Member Administrator

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    G`day Setaf,
    I use 3mm LED`s usually.
    I dare say that if you use 3 LEd`s from a strip you will find the lighting very bright. It would need some serious resistors to drop the brightness or a coat of paint over the LEDs
    I use old 12 volt transformer / speed controllers for my lighting. I use resistors to cope with 12 volts and then I dial down the input from the power to suit the situation.
    So the controller acts like a dimmer.
    I have used copper tape once and I hate the stuff.......some others may have had more success with it, but I would rather use wire.
    :tophat:Gormo
     
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  3. Setaf

    Setaf Full Member

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    Hi Gormo,
    I have thought about the spare/old transformer as a dimmer controller/switch. The other idea I had was to use a variable wall wart and dial down the voltage with that. Most offer
    3V 4.5V 5V 6V 7.5V 9V 12V. This would be for the strip lights. I assume this way could also be used for the 3mm individuals? I've been thinking I might have to use resistors for the 3mm lights, but thought maybe I could get around that by the wall wart regulated power. I appreciate the advice as I'm a green novice with this area and of course have no experience.
     
  4. Jim Freight

    Jim Freight Full Member

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    Hi, whatever voltage you use, LEDs on their own will always require current limiting resistors, values vary with different LEDs but nominally the current should be limited to 5-10 mA with approximately a 2V drop across the LED.

    The higher the voltage applied from your PSU the higher the resistor value needs to be.

    Jim
     
  5. paul_l

    paul_l Staff Member Administrator

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    Hi Setaf

    To get an LED to light you need to reach the forward voltage of the LED (normally between 1.8V and 3.3V depending on type and colour). Also whether you wire them in series or parallel.
    In series the forward voltage will be the total of the forward voltages e.g. 6 diodes with forward voltage 1.8V each you would need over 10.8V for the led's to come on
    In parallel the forward voltage is equal to the rating of the diode e.g 1.8V.

    As Jim noted above, you will always need to fit a current limiting resistor, without one the led's will act like a short and dump the full current through them until some thing fails - hopefully the led,and not the power source or wireing which may go up in flames.

    The series connection has the advantage of allowing you to tweak the forward voltage closer to your power supply, if you are having to reduce the supply voltage down, then you are loosing the excess energy via heat, not good in enclosed areas.

    Paul
     
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  6. Setaf

    Setaf Full Member

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    Thanks everyone for the advice, much appreciated. I'm gaining a bit more understanding of all this.
     
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  7. gormo

    gormo Staff Member Administrator

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    This may help you work out what value resistor you need to use with your LEDs. Just put in the supply voltage eg. 12 volts and it will calculate it for you.
    You will also notice that if you have LED`s in a daisy chain (more than 1 LED in series ), the value of the resistor will change.
    https://ledcalculator.net/
    :tophat:Gormo
     
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  8. Setaf

    Setaf Full Member

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    Thanks Gormo. Appreciated.
     
  9. Jim Freight

    Jim Freight Full Member

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    Regarding copper foil tape, I did look at this even as an option for a DCC power bus but in practice it is deceptively thin despite it's width which means that, it's cross-sectional area (csa) is very small which means that it's electrical current carrying capacity is very low.

    Also it may be torn or damaged easily, in which case the csa is reduced much further and for any significant current may melt as an overloaded fuse.

    How well the adhesive backing lasts if it gets warm is another issue.

    It would be ok for a few LEDs but if it should come unstuck and cause a short circuit and the power supply does not have a means of limiting the current it could become a fire hazard particularly in a building made of card.

    Jim
     
  10. Setaf

    Setaf Full Member

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    Yes, I was wondering something of the same thing. Watching it on YouTube it seemed quite thin. It looked like a great alternative to wires in a building at first, but as you point out, one would have to be very careful and not too trusting using it as it stands now. And......I'm hoping to start using many more card buildings now as a great alternative to plastic much of which is due to financial concerns.
     
  11. Jim Freight

    Jim Freight Full Member

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    Some very fine models have and still are being made using card instead of plastic sheet.

    Embossed brick and other textured plastic sheets are okay up to a point, but in 1:76 scale mortar lines on brickwork would be so shallow that printed card is actually more realistic, similarly with tiled and slate covered roofs.

    Somehow we tend to go for exaggerated details in this scale, I'm very guilty of that.

    For my colliery buildings which will be scratch built, I shall be using mount board foam for the frame, brick papers, inset plastic channels for girder beams and printed weathered roof slate sheets, so a more realistic combination for 1:76 than embossed sheets (IMO) :)

    My dockside warehouses come with laser cut roof tiles, but there again I think that printed weathered tile or slates would look much better in 1:76 scale.

    Jim
     
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  12. gormo

    gormo Staff Member Administrator

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    G`day Setaf,
    All of my major buildings are made from card, either kits or scratch built.
    I agree with Jim`s assessment of building papers etc and I think they look rather good.
    I save good cereal box card which is handy for all sorts of fine strips or whatever. It can also be laminated to build up it`s thickness, however needs to be pressed flat whilst drying.
    My preferred card for scratch building is mounting card as used in picture framing. It comes in big sheets and is very rigid yet easy to cut with a good knife and straight edge.
    An example of a building being built from mounting board card and brick paper.

    IMG20210919162355.jpg

    :tophat:Gormo
     
  13. Setaf

    Setaf Full Member

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    I've done a great deal of browsing for card buildings and have seen some truly outstanding examples being offered and consequently the same for ones completed. I've accumulated a file of many free samples as well as a half dozen purchases. Still studying the different offerings as far as card weight/thickness needed and also the option of regular paper glued to card. I have quite a stock of foam board, mounting board and cereal box. :) My actual printer card at the moment is 110 weight which actually was purchased for ham radio QSL cards.

    Steve
     
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  14. Setaf

    Setaf Full Member

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    Love it! It's what I hope to build up to.....patience in my case is needed, but as I get older it's gradually coming. See my reply to Jim. Thanks for the suggestion. I at first thought to just print out on card and use, but lately have wandered more towards regular paper cereal box or mounting board. As mentioned to Jim, I have both on hand. Mounting board came form a craft store local that went out of business, but before that I picked up a quantity of scrap from their framing business.

    Steve

    Steve
     
  15. Andy_Sollis

    Andy_Sollis Staff Member Moderator

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    I still tend to use a battery for LED power unless it’s pre purchased (as a light or lamp shade etc) where diode and wires are pre fitted..

    With a battery, you can choose when it’s on or off (separate to the layout subject to where it is..

    indeed, there are some button cell battery boxes that will power LEDs that now have an 8 hrs on and 16 off switch so they come on in an evening and go off on their own
     
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  16. Walkingthedog

    Walkingthedog Full Member

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    Run my lights off a spare controlled outlet on my 4 track Gaugemaster controller.
     
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  17. Jim Freight

    Jim Freight Full Member

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    Batteries are a last resort in my book, and then I go for rechargeable :scratchchin: Jim
     
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  18. Setaf

    Setaf Full Member

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    Hi Andy.
    I have seriously thought about using batteries in at least some of my lighting. I have seen them referred to in a couple other places and can see some advantages. I would say generally, that for building and street lights, they wouldn't have a lot of "on" time and batteries would last quite some time. They might offer a little bit more control over certain lights or groups of lights without a lot of extra switches having to be installed if fed from a central feed. Actually, I have a couple strings 20 light strings of Christmas LEDs that are battery powered which I've thought of using in a couple applications.

    This is one thing of several that I like of this forum is all the ideas that are shared with the knowledge that there are more than a couple ways to do things. I've already picked up quite a few ideas from here and they are appreciated.

    Steve
     
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  19. Setaf

    Setaf Full Member

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    Hi Jim,
    Are you like Motel 6 here in the states and you keep the light burning? :avatar: Actually, I do have a recharger downstairs that might be just what I need. :scratchchin: :D:D
     
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  20. Jim Freight

    Jim Freight Full Member

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    Hi Steve

    Quite the opposite, I'd rather sit in low daylight until I really have to turn on the lights, I hate artificial light, trouble is it's essential for any closeup work these days :(

    I have kept many an old charger/adapter over the years and place them where I need them, must admit I have not put any scenery based lighting in place but I do use these old adaptors to power turntables, CDUs for points and the cement works rotating kiln motor.

    Jim
     
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