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Lighting Intensity

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  • Member since
    May 2008
  • From: Miles City, Montana
  • 2,289 posts
Posted by FRRYKid on Sunday, August 28, 2022 3:54 AM

rwissbaum

So far, nobody has mentioned what I think are two key points. First, you mention you are using the AC terminals on your transformer to provide power. Depending on the quality of your transformer, you could be providing up to twice the nominal voltage to your lights. This is because transformers require a minimum current to achieve stable operation - below that minimum, the supply voltage increases. I had a very old MRC power pack which delivered 31 VAC on the 16 VAC terminals, and 26 VDC on the 12 VDC terminals. Moral: check the actual voltage. (A 2 amp 12 VDC regulated power wall wart costs about $15 on Amazon, and it will deliver a steady 12 VDC between zero and 2 amps.)

As the hobby transformer I'm using was a freebie, I'm not going to knock it too much. (The lights were switched to it when I discovered that activating a remote turnout dimmed the lights when they were hooked to the big MRC pack, meaning the system is a bit overloaded.) When I have checked the AC voltage IMS it runs somewhere between 16 and 20 which is within the norm for those packs.

rwissbaum

Second, some LEDs require amazingly high resistances - say, 5,000+ Ohms - before they become noticeably dimmer. An LED which nominally requires 20 mA might be nearly as bright down to 1 mA. This is very different behavior from incandescent bulbs, where brightness decreases almost linearly with increasing resistance. 

The LEDs in these lights appear to be a SMD type. They are small and darkened to the higher value resisitors. IMS I went up to a 4.7K one and decided it was too dark.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
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Posted by rwissbaum on Saturday, August 27, 2022 8:51 PM

So far, nobody has mentioned what I think are two key points. First, you mention you are using the AC terminals on your transformer to provide power. Depending on the quality of your transformer, you could be providing up to twice the nominal voltage to your lights. This is because transformers require a minimum current to achieve stable operation - below that minimum, the supply voltage increases. I had a very old MRC power pack which delivered 31 VAC on the 16 VAC terminals, and 26 VDC on the 12 VDC terminals. Moral: check the actual voltage. (A 2 amp 12 VDC regulated power wall wart costs about $15 on Amazon, and it will deliver a steady 12 VDC between zero and 2 amps.)

Second, some LEDs require amazingly high resistances - say, 5,000+ Ohms - before they become noticeably dimmer. An LED which nominally requires 20 mA might be nearly as bright down to 1 mA. This is very different behavior from incandescent bulbs, where brightness decreases almost linearly with increasing resistance.

  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Friday, August 26, 2022 4:45 PM

PennsyLou
Ohm is a measure of resistance, zero ohms is zero resistance, therefore it is not a resistor.

https://en.wikipedia.org/wiki/Zero-ohm_link

Good Luck, Ed

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Posted by PennsyLou on Friday, August 26, 2022 6:29 AM

maxman

  a 0 ohm resistor?

 

 
Isn't this an oxymoron?  Ohm is a measure of resistance, zero ohms is zero resistance, therefore it is not a resistor.
  • Member since
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  • From: Miles City, Montana
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Posted by FRRYKid on Friday, August 26, 2022 2:52 AM

For reference I went with a different assortment than the one suggested. (http://www.ebay.com/itm/174992794630) For what I am aiming for it works.

As to the building lighting question, that is the next thing on the list for the streets. I have a few freight car projects that are redirecting the budget. The "camera" I used is the same cell phone that took the first photo posted.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Thursday, August 25, 2022 11:20 PM

maxman
Is there really a place where you would use a 0 ohm resistor?

None that I'm aware of Whistling I have seen PC boards with jumper wires or bridging wires and these are presumably 0 Ω. 

I've purchased maybe three or four of these assortments over the years from different vendors and haven't found a 0 Ω resistor yet. I simply found an Amazon link to a similar assortment — there are dozens in various wattages and styles. I only posted that particular set as an example.

https://www.allaboutcircuits.com/technical-articles/what-are-zero-ohm-resistors-how-are-they-used-in-circuit-design/

Wish Randy was here to "splain" it.

https://en.wikipedia.org/wiki/Zero-ohm_link

 

Good Luck, Ed

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Posted by maxman on Thursday, August 25, 2022 10:59 PM

gmpullman
Resistor Assortments are very reasonable at Amazon.

I looked at that assortment and see that one of the 50 resistors is 0 ohms.

Is there really a place where you would use a 0 ohm resistor?

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  • From: Bradford, Ontario
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Posted by hon30critter on Thursday, August 25, 2022 9:04 PM

FRRYKid
This is with a 2.2 K ohm resistor wired into the main distribution plug.

Hi FRRYKid,

The picture is extremely dim, but I suspect that is a result of the camera setting rather than the resistors. A 2.2k resistor shouldn't have dimmed the lights by that much.

I think that you are the best judge of what looks right to you. The ideal effect would be what Ed showed in his bridge photo where there are dark spots between the lamps.

Since this is a downtown scene I'm going to assume that most of the building fronts and windows will be illumunated. My suggestion would be to get those lights installed and reduced to proper light levels before adjusting tne street lights (Ed make a really good point about lower lighting levels being more enticing). Once you have the building lighting sorted out, then adjust the street lamps so that they can be seen but are not blinding. The circle of light under the lamp is what you want to see.

My 2 Cents

Have fun,

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    May 2008
  • From: Miles City, Montana
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Posted by FRRYKid on Tuesday, August 23, 2022 11:52 PM

Apologies for the delay in getting back to the post but I finally got to install a resistor into the circuit. This picture is what I came up with.

https://photos.app.goo.gl/NQdvKJjmfNRAY4Dc9

This is with a 2.2 K ohm resistor wired into the main distribution plug.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
  • Member since
    May 2008
  • From: Miles City, Montana
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Posted by FRRYKid on Monday, August 8, 2022 3:19 AM

gmpullman

Resistor Assortments are very reasonable at Amazon.

I start with the usual 1K (1000) Ω and I use a very accurate variable power supply to slowly raise the voltage toward 12 VDC. If I see the LED getting too bright I then substitute a 1.6, 1.8, 2.2 or sometimes even higher value.

This Coke machine has a tiny SMD LED in it and I seem to recall I needed a 3,600 Ω resistor to get it to dim enough so it didn't wash out the signage.

Before:

 Feed mill Coke machine1 by Edmund, on Flickr

     after:

 Coke_Machine_crop by Edmund, on Flickr

It helps to know the exact voltage that your DC power supply for lighting is. I use supplies that are very close to 12V.

The assortment I linked to above contains 50 1K resistors and you can add (daisy chain) additional resistors until you get a value that provides the light intensity of your liking.

Thanks to all for your compliments on my scenes Smile

Cheers, Ed 

My lights are powered on the AC side of the power in order to leave the DC available for the trains.

I will also have to look at that assortment as well.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Sunday, August 7, 2022 11:35 PM

Resistor Assortments are very reasonable at Amazon.

I start with the usual 1K (1000) Ω and I use a very accurate variable power supply to slowly raise the voltage toward 12 VDC. If I see the LED getting too bright I then substitute a 1.6, 1.8, 2.2 or sometimes even higher value.

This Coke machine has a tiny SMD LED in it and I seem to recall I needed a 3,600 Ω resistor to get it to dim enough so it didn't wash out the signage.

Before:

 Feed mill Coke machine1 by Edmund, on Flickr

     after:

 Coke_Machine_crop by Edmund, on Flickr

It helps to know the exact voltage that your DC power supply for lighting is. I use supplies that are very close to 12V.

The assortment I linked to above contains 50 1K resistors and you can add (daisy chain) additional resistors until you get a value that provides the light intensity of your liking.

Thanks to all for your compliments on my scenes Smile

Cheers, Ed

  • Member since
    May 2008
  • From: Miles City, Montana
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Posted by FRRYKid on Sunday, August 7, 2022 9:30 PM

As I don't have easy access to resistors, before I go crazy guessing at values, what value would you all suggest to dim down my lights?

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
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  • From: Bedford, MA, USA
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Posted by MisterBeasley on Sunday, August 7, 2022 12:04 PM

I model the Transition Era so I prefer the softer warm glow of incandescent lamps.  I usually get 16 volt lamps and run them on a 12 volt bus.  This keeps the bulbs from being too bright and greatly prolongs their life.

It takes an iron man to play with a toy iron horse. 

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Posted by IDRick on Sunday, August 7, 2022 10:04 AM

Ed, you are such a master modeler! For informative post and such delightful imagery!  You should do a video of your layout! 

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Posted by wrench567 on Sunday, August 7, 2022 7:34 AM

  I'm with Ed on this. The street lights running down my street leaves dark spots between them. My driveway just happens to be in the middle. But at least there's a fire plug next to it. I installed solar lighting facing the driveway so when a car pulls in the lights come on.

  I have seen model structure lighting on layouts when on light up the whole area around the structure and you can see the bracing inside the walls like an X-ray.

     Pete.

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Posted by gmpullman on Sunday, August 7, 2022 2:44 AM

In nearly every case of modeling lighting I prefer to err on the side of dimmer is better than overly bright. However there are some variables to be considered and the main one is how much ambient room lighting you will have when creating your night scene.

Having lights that are obviously too bright, unless you're modeling a Kiss or Pink Floyd concert, will give a toy-like impression to the visitor. I've found that folks that peer into dimly-lit model structure rooms are more curious and tend to look longer to see the details within.

Here's one of my street views where each lamp provides a pool of light and slightly darker areas between poles:

 Bridge1 by Edmund, on Flickr

I remember as a kid riding in the car at night when all the street lights were incandescent and they weren't all that bright. Watching the overhead lights always made me sleepy. There were dark, shadowy areas between light poles unlike most areas today with high pressure sodium or LED lighting providing almost shadowless light.

This car shop scene is another example where the dimly-lit areas and shadows become part of the interest and allure to the night-time feeling. A viewer wants to keep looking to see what might be lurking in the shadows.

 Car_shop by Edmund, on Flickr

I recently installed some W-S decorative lamp posts and in the initial resistor choice I realized the lamps were way too bright.

 Street-Scene-wide by Edmund, on Flickr

 Street-Scene by Edmund, on Flickr

Installing 2.2 or 2.6K resistors is on my to-do list. Another consideration for these is the fact that you are looking directly at the LED chip rather than reflected light which also warrants reducing their intensity.

This example shows how shadows and lighting can enhance a scene (this is a work-in-progress for now) but it shows what I'm attempting to demonstrate that "less is more" when it comes to brightness of the light source:

 Hotel-noir by Edmund, on Flickr

 I agree with your own assessment that the lighting in your sample photo could be reduced in intensity a bit.

 Union_Sta_departure2_crop by Edmund, on Flickr

Hope that helps, Ed

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  • From: Miles City, Montana
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Lighting Intensity
Posted by FRRYKid on Sunday, August 7, 2022 2:05 AM

This is an opinion question for those with street lights on their layouts. Are the lights in this picture (https://photos.app.goo.gl/oXwp16zMHiagv1wG6) too intense? This was taken with no external lights and no flash on an older cell phone without light adjustments. By my uneducated eyeball, they are. However, I don't have a base to go from. Each light has a resistor wired to to it and then in parallel. There are three more streets with these same lights. Each street is on its own circuit that plugs into one side of a WS linker plug. The other side then connects with single wires to one side of a central plug. The other side of that central plug then connects to an Atlas Connector switch with single wires.

As usual any ideas or thoughts would be most welcomed.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.

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