DC Power Supply for LEDS...


Thanks, and yep, I am getting an edumication definitely, especially electrically. There are a lot of great people here who are very knowledgeable and experienced, and where I am concerned, very patient as well.

I ask, what must seem like a lot of dumb questions, and have always gotten great advice, even though some times I don't understand it completely. From my perspective though, I am "slowly" picking this stuff up and that is creating a little more confidence which makes me want to learn more. In short, expect more "dumb questions" :)
 
You can create a lot of cool effects with LEDs. With the myriad of shapes and colors available, all sorts of things are possible. My diner uses the blue white LEDs inside to represent flourescent lighting. while the "neon" tube lights are done by mounting thin rectangular LEDs end to end creating a continuous thread of light ....

diner.jpg

Mark.
 
Mark,

Ohh so much to learn, so little time :)

Now I have a better understanding of LEDS and Resistors, I can see myself playing around with LEDS a lot and adapting different colors for different things. Darn, I am even contemplating making my own street lights ... if only I knew how :)

The only LEDS I have seen have been the "standard" type, have never come across rectangular ones, but I can see they would be a lot of fun to play around with.
 
wombat457 said:
The only LEDS I have seen have been the "standard" type, have never come across rectangular ones, but I can see they would be a lot of fun to play around with.
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You can cut and shape the "dome" of a normal LED to almost any shape you want. They are mostly just plastic. Just don't get down into the real electronic part.

Another thing you can do is drill a small hole into the led and put a fiber optic cable into it. If the fiber optic is the kind that "leaks" light you can form it into "neon" lights.
 
You can make fiber optics leak by abrading the outside of the fiber. Either chemically or physical abrasion might work, so experiment.
 
wombat457, it is easier to understand when you consider that brightness of an LED is directly proportional to the current it draws, therefore we can safely assume that brightness increases and decreases with current. Since we can control the amount of current being fed to an LED by adding a resistor in series with that particular LED, we are thereby controlling the brightness of the LED. If a resistive trimmer is used, it’ll directly control the amount of brightness.
 
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Hey guys, thought I would jump in here as this subject relates to my current project.

I have purchased several street lights from a supplier in China. Very nice lights. They are rated for 12v DC, and rated at 100ma. My plan is to probably put between 25-30 lights around the layout. In testing them today on a DC transformer they are really bright. So I reduced the voltage down to about 6.5 volts, and they look great. At full voltage, the LEDs were really hot. Reducing the voltage really cooled them down, and the brightness is much more subdued, which will probably look better. So I would suspect that around half voltage will be the norm.

Now, since they are rated at 100ma, and given the number of LEDs to install, I will need in the neighborhood of a 4-5A supply. My thought is to get a variable supply, so I can adjust the voltage if necessary. Saying that, does anyone know of an inexpensive 12v 5A variable supply on the market? I have done some searches and haven't come up with anything to speak of.

I am open to any suggestions if there is better way to make this all work.

Thanks.

Ted
 
That's going to be a little tough.

Anyway...

https://www.superbrightleds.com/cat/power-supplies/

Another way to control the brightness is with PWM (pulse width modulation).

https://www.superbrightleds.com/cat/single-color-dimmer-switches/


So they have a 12v 50w (appx 4.2 amps) power supply...

https://www.superbrightleds.com/mor...dc-enclosed-power-supply/70/#/attributes/2880

which you could use with this dimmer (which handles 8 amps)...

https://www.superbrightleds.com/mor...12-24-volt-dc-single-color-led-dimmer/62/365/


but your at $45.
 
I gotta ask .... are you sure they are rated at 100ma ? Most all LEDs have a rating of no higher than 20ma at full brightness. Even small bulbs seldom have a rating any higher than 40ma. Are you sure they aren't bulbs ? Even at maximum rated current, an LED does not get hot, let alone warm.

Try sticking your meter inline with the power supply set to 6.5 volts and get an actual current rating the street lights are actually drawing, then you can more accurately determine what you need for a power supply.

Mark.
 
Thanks for all the comments. Will take look at them a little closer hopefully tomorrow. Don't go away yet.

Ted
 
tmiller said:
N I will need in the neighborhood of a 4-5A supply. My thought is to get a variable supply, so I can adjust the voltage if necessary. Saying that, does anyone know of an inexpensive 12v 5A variable supply on the market?

I am open to any suggestions if there is better way to make this all work.
Click to expand...
No, but instead of getting one single supply why not get 5 smaller ones. I frequent the thrift store and pick up 12v 1 and 2 amp supplies all the time for something like $2 each. You could also just buy 6.8V supplies (seems to be a common size for who knows what reason) or whatever voltage you really want. Many of them also have the plug on the end, so you could just wire your lights to a female plug on the layout and swap for different voltages at will.
 
Caution about "wall warts" .... If you want to go that route, be sure the output is regulated (it should say so on it). An unregulated supply will output a much higher voltage if the rated load isn't attained. These types of wall packs are usually designed for specific purposes (cordless phones, chargers, etc.) and as such, put out the rated voltage when the load they are designed for is seen.

An unregulated wall pack that is intended for a cordless phone may be 12 volts at 250ma. If the load on the pack is less than 250ma, the voltage will be higher - sometimes by quite a bit !

A regulated output is just that - if it's labelled for 12 volts, it will be 12 volts regardless of the load (up to it's max rating of course).

Mark.
 
Hey Iron horseman

Yes I did purchase them from "wehonest". Dealt with them before? Here are the ones I purchased:

http://www.ebay.com/itm/15-pcs-HO-s...985349?pt=Model_RR_Trains&hash=item3a91215a85 These are lamps

http://www.ebay.com/itm/15-pcs-HO-s...985349?pt=Model_RR_Trains&hash=item3a91215a85 These are lamps

http://www.ebay.com/itm/2-pcs-HO-sc...851814?pt=Model_RR_Trains&hash=item3ce65c61e6 These are LEDs

I stand corrected. The street lights are lamps and the yard lights are LEDs.

Now what does that do for the mix?

Ted
 
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The most significant difference between incandescent lamps and LEDs is the current need to power them. LEDs use considerably less and generate very little heat.

I can only speak theoretically about how that may affect you. I think it's best to leave that for the Iron Horsemen. I do think his idea of multiple power supplies is a great one!
 
fcwilt said:
That's going to be a little tough.

Anyway...

https://www.superbrightleds.com/cat/power-supplies/

Another way to control the brightness is with PWM (pulse width modulation).

https://www.superbrightleds.com/cat/single-color-dimmer-switches/


So they have a 12v 50w (appx 4.2 amps) power supply...

https://www.superbrightleds.com/mor...dc-enclosed-power-supply/70/#/attributes/2880

which you could use with this dimmer (which handles 8 amps)...

https://www.superbrightleds.com/mor...12-24-volt-dc-single-color-led-dimmer/62/365/


but your at $45.
Click to expand...

This is a case where I'd say it's worth spending to get it right... I swear by Circuit Specialists power supplies, and for not much more than a cheapo, you get a real unit supplying well-regulated, controllable non-dirty power. For a few bucks more, you'll quickly make back the difference in NON-blown LEDs, other little components, etc.

e.g. their 5-amp supply is $60, 0-30v, 0-5a fully adjustable, nice LCD display, etc. http://www.circuitspecialists.com/csi3005sm.html
 
For power supplies to run accessories, I buy laptop power supplies off ebay. You can get them in a variety of voltages and the output doesn't get much "cleaner", and they are usually rated in the 5 to 10 amp range. They can be had all day long for less than $10.

Mark.
 
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