# Light's Bright!!

Discussion in 'FAQs' started by Matt Probst, Jun 21, 2003.

1. ### Matt ProbstMember

Question...I have grain of wheats that I've been using to light poles and structures with...
To me, they just seem too bright. Does anyone know of a way to dim them a bit or should I replace them all with grain of rice bulbs? Or are the GOR bulbs about the same in brightness?
Any solutions would be appreciated!
Thanks.

Matt--Hershey, Pa.
2. ### interurbanActive Member

Hi Matt are you using 12v bulbs????
If so you can use a 120v reducer to 8volt that would have run a radio
You must have one kicking around somewhere, if not check out an electric shop.
It will also give your bulbs a lot longer life.
3. ### ezdaysOut AZ way

Matt,

You can reduce the brightness of any bulb by reducing the voltage. Adding a resistor in series with the bulb is probably the easiest way to go. To figure it out, you have to do a bit of electronic math called "ohms law", but instead, just start off with a resistor in the 500 to 800 ohm range and try it. If it is still too bright, increase the resistor value. If it now is too dim, decrease the value. This is called doing it by "empirical calculations" and equires no knowledge of ohms law.

Don
4. ### ClerkActive Member

I read sometime back on one of these RR forums that by wireing two lights in series will reduce the brightness. I tried it and it worked.
5. ### belgMember

My hobby shop guy uses and old power pack and as you adjust the speed the ligths will get dimmer and brighter.Attach to the track terminals not the accesories set.Your bulbs must be rated at 12 v.
6. ### ezdaysOut AZ way

Yes, wiring two lights in series halves the voltage to each one and halves the light output. It also increases the life of the bulb beyond belief.

Using the DC output from an old power pack is an excellent way to go as well and I plan on doing that to a group of lights that I want variable control over. Just one caution though, be sure the voltage doesn't go much over the rated voltage of the light otherwise it will shorten the life of the bulb beyond belief. many power packs can go up to 18 volts or higher.

As an example, a 12 volt bulb running at 12 volts might be rated for 1000 hours of life. Run the same bulb at 10 volts and it might be good for 10,000 hours. Run it at 14 volts, and it might only last a few hours. Also be careful using a "cheapie" power pack. The output may be adjustable, but it is not regulated or filtered. Meaning that the output is subjected to variations dependent on the load and the input. There is no protection against spikes. Putting a large capacitor on the output helps tremendously.

Don
7. ### Matt ProbstMember

Thanks for all the replies guys! I have an old power pack I plan on changing out some day and that will probably be used to power lights as Don suggested. Are GOR bulbs the way to go though? My GOWs measure out to about 2-1/2 scale feet long in HO and are way too big to be used on "outside" fixtures. I'de like something alot smaller but are simple to wire...
For the interim though, I'll probably just wire a bunch of lights in a series in hopes of reducing some of the brightness.

Matt--Hershey, Pa.
8. ### ezdaysOut AZ way

I don't know of anything smaller in a incandecent bulb, but there are LEDs that are smaller. Unfortunately, they don't throw off much light and are used mainly as indicators, not light sources.
Just remember, putting two in series will reduct the voltage to each lamp to 50%, four in series will make that 25%. The light intensity may not follow that formual.

Don
9. ### RailRonActive Member

Hey Matt,

My 2¢ worth: Use the GOWs (which you can't see directly) for inside lighting and the GORs (which are visible) for outside lamps like streetlamps, ramp lighting etc.

Today there are also very small white LEDs available, but - apart from being not exactly cheap - there is another difficulty: They use lower voltage (1.5 - 3 Volts), so you have to calculate the value of voltage dropping resistors and add them into the circuit. And apart from that, 'white' LEDs have a bluish tinge which doesn't look like a normal incandescent lamp (more like the modern piercing headlights of automobiles).

So as the others said: Take advantage of your old 12-18 Volt power pack, wire two bulbs in series (not more, or you'll get an orange light!), and in the most cases the resulting (yellowish) light will be very pleasing to the eye.

And try to post a 'night shot' when you're through with your project!

Ron
10. ### belgMember

? Capacitor?

Don my electronic skills are very very poor,how do I size the capacitor to the amount of lights I use and would it change if those lights were run in series or series parallel?
11. ### ezdaysOut AZ way

Re: ? Capacitor?

You don't have to. I've built power supplies as part of the products we manufactured and found on a 12 volt DC supply that a 1000 mfd capacitor gave reasonable good filtering from no load to a full amp load, ( the supply was rated for that). We would charge extra for upping that to 2200 mfd. for those customers that were a bit more paranoid. We would also put a smaller value capacitor in parallel with the big one to react faster to spikes. Your major concern is to be sure the capacitor has a voltage rating higher than the maximum voltage output of the power pack. We would use a 25 volt rating on our 12 volt supplies, and 50 volt rating on our 24 volt ones. The other concern is that once you have the capacitor in place, you want to be sure you don't reverse to polarity of the output, otherwise the capacitor will become hot, smoke and kinda blow up.....

If you want to discuss this further, let me know. I could go on and on and on but I'm starting to get sleepy.....

Don
12. ### StrthokyMember

hehe I would try not to touch that capacitor on the contacts after you hook any juice up to it either
13. ### Matt ProbstMember

Thanks for the insight folks!!!

Matt--Hershey, Pa.
14. ### VicActive Member

Hi Matt, Yes there are incandescent blubs much smaller than the ones that you are talking about...check the lighting section of the Walthers catalog. Usually the very small bulbs are 1.5 volt rather than 12V but you can get a cheap "wall-wart" transformer that will light several hundred of them....One mfg. that comes to mind is Minatronics. They are a pit pricey from Walthers but usually they can be bought in bulk direct very resonable.
15. ### GNRailMember

Another source for small lights is Mouser Electronics.

This link is to the catalogue page for minature lamps.

http://www.mouser.com/catalog/614/85.pdf

If I did the math right they have a bulb that measures 16.25" by 8.12" in HO they also run at 5 volts.

Another option to control the brightness is to use a regulator fed from the fixed dc supply from your power pack. Depending which one you buy they can take inputs of up to 30v. They are available in a number of fixed voltage outputs and simple to use. Attached is a simple circiut. Remember if you are using a lot of current be sure to use a proper heat sink.

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16. ### kf4jqdActive Member

Wiring

Hello All:

I maybe the one who mention about wiring lights in series. You can also use resistors. Here is a simple electronic formula to remember. If you have a 12 volt power source with 2 lights wired in series. There is a 6v voltage drop across each light. If you have 3 lights wired in series. You will have a 4v voltage drop. See the patern. So, if you have a 12v bulb and you wire it in series with another one to a 12v source. You will only be feeding the light with 6 volts! 6+6=12 So, the light dims!!! Did I mention the buld last twice as long!

As for power supplies. On my layout, I use an old note book computer power supply! I also have an Astron 13.8v/35amp power supply. That is used for my Ham Radios. Just imagine the lights with that baby!

Andy

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17. ### jim currieActive Member

for small lights i have been using fiber optics they can produce a tight beam or wide beam depending on how end is treated ,they make the size of light sorce a moot point on old layout i ran all of the lights in industral section off of one 50 watt lamp.
18. ### ezdaysOut AZ way

Andy,

Just a word of caution. In order to divide the voltage equally if wired in series, all lights have to be the same type. Remember. bulbs are rated for both voltage and current with higher current lamps usually burning brighter than lower current one. If one bulb was rated for twice the current as another, putting them in series would result in the higher current one dropping less voltage across it.

Two lamps may look the same, but be very different.

Don
19. ### kf4jqdActive Member

I forgot!

Thanks for the reminder! Current does play an important role. Remember: NEVER draw more current than your power supply can handle. Safety Reminder: ALWAYS have a fuse in line!!!

Andy
20. ### VicActive Member

Hi All, For those that might be "electrically challanged" there's some real simple math called OHM"S LAW that will take all of the mystery out of this electrical fanaggling !!! Check out the link below for an explanation....if you can do 5th grade math then you're on your way to being an electrical genius!!!!

73, de K4VIC